Remove Electronic signature Form Later
Make the most out of your eSignature workflows with airSlate SignNow
Extensive suite of eSignature tools
Robust integration and API capabilities
Advanced security and compliance
Various collaboration tools
Enjoyable and stress-free signing experience
Extensive support
How To Remove Sign Document
Keep your eSignature workflows on track
Our user reviews speak for themselves
Remove Electronic signature Form Later. Check out one of the most user-warm and friendly experience with airSlate SignNow. Deal with your whole record handling and expressing method electronically. Move from portable, paper-centered and erroneous workflows to automated, digital and flawless. You can easily produce, supply and indication any files on any device just about anywhere. Ensure that your airSlate SignNow company instances don't slip over the top.
Find out how to Remove Electronic signature Form Later. Adhere to the basic manual to start:
- Design your airSlate SignNow bank account in click throughs or sign in along with your Facebook or Google accounts.
- Enjoy the 30-working day free trial or select a pricing prepare that's ideal for you.
- Find any lawful web template, construct online fillable forms and share them tightly.
- Use superior characteristics to Remove Electronic signature Form Later.
- Sign, personalize putting your signature on order and acquire in-individual signatures 10 times faster.
- Set automatic alerts and get notifications at each move.
Transferring your jobs into airSlate SignNow is easy. What follows is a straightforward procedure to Remove Electronic signature Form Later, as well as recommendations and also hardwearing . co-workers and companions for better cooperation. Inspire your staff with the very best tools to keep in addition to enterprise operations. Boost output and range your small business more quickly.
How it works
Rate your experience
-
Best ROI. Our customers achieve an average 7x ROI within the first six months.
-
Scales with your use cases. From SMBs to mid-market, airSlate SignNow delivers results for businesses of all sizes.
-
Intuitive UI and API. Sign and send documents from your apps in minutes.
A smarter way to work: —how to industry sign banking integrate
FAQs
-
How does anyone make money making porn films when they're all free on the web?
This is going to be fun. Although I could elaborate my answer and broaden it up, I will stick to the question's details.Brazzers is owned by a company called MindGeek. Mindgeek happens to own also Digital Playground. Brazzers and Digital Playground shoot porn scenes and wrap them into DVDs or add them to their premium websites (sometimes both). Some money come from users who subscribe to those websites or buy the DVDs, usually because they want to get entertained by first-hand material. A lot of that material, however, end up being available "for free" on PornHub and RedTube. I have put for free in quotes because nothing is for free, especially in the adult entertainment business. AdvertisingWhen you watch a free movie or a scene on a porn tube you are forced to interact with some form of advertising at some point. Being it when you click on the play button or even before that as soon as you have loaded the page containing the video, the porn tube will deliver you a piece of advertising. It doesn't matter if you pay attention to it or not, if you follow it up or not: you have spent a part of your time in interacting with that particular ad and someone is going to cash your time in. It may seem free to you at that time, but in truth you have paid with your visit and if you keep reading you will realize that you might be ending up pay with real money too at some point.Cookies and privacyThe tube installs a cookie (well, more than one...a lot) on your computer which tracks and collects a lot of information about you and your browsing habits. Some of these cookies are temporary and expire soon after you leave the site; some others, however, are persistent and they get stored on your computer forever (or until you delete them of course). The sad (or scary, it depends how you look at it) thing is that when you visit a tube, your computer does not just get injected with the site cookies but also with third parties cookies, "delivered" to you not only any time you interact with an ad, but more often than not also as soon as you load the first page of that site. This is a typical excerpt from the privacy page on porn tubes:We have to emphasize that our Website includes Third-Party’s Content or some other type of external services. These providers, partners and contents use Cookies as well though We have no control or insights over their Cookies and it’s usage. For these reasons, We advise You to read carefully any Cookie Policy issued by our Partners in order to avoid any misuse of Your personal information collected and processed by these Administrators.How you pay for free pornSo now, not only you have watched an ad that you would have otherwise happily skipped, but you have also passed a certain amount of private information to a third party company, which will use it to push you targeted ads for as long as their cookie resides on your computer. And chances are that before or after you will buy something with real money. So, to recap, this is how you pay for free porn:The video you watch is often attached to a referral code. An adult film studio add their videos to PornHub which have signed up to that company referral program. When you watch the video that referral code and its related information are stored on your computer (yes, another cookie). If you will visit the studio's website, one day, and you will buy something in there, a slice of the sale will be turned to the initial referrer (the tube, in this case).Even if you will never visit that company's website, the tube has forced one or more ads to you and the company featured in the ad has paid the tube a certain amount of money.The company featured on the ad or their intermediary ads agency has paid for injecting a cookie on your computer in order to collect sensitive private data about your browsing history and taste. This same data have been grabbed and will be used also by the tube and not necessarily on the tube site itself. But I will talk about this later.Even if you used something like AdBlock, non-intrusive ads are still served to you and cookies still get installed in your machine. Furthermore, the use of adblock is often countered by artificially crafted workarounds such as disabling some features on the tube website and making it a nightmare to browse it.Hence, it is clear that you don't watch movies for free: you pay by watching ads and by "selling" your privacy (and personal data, in the digital era, are gold). Adult tubes capitalize on their traffic by referring sales to other websites and by selling ads and users' private information, as well as premium subscriptions.Brazzers and Digital PlaygroundGoing back to the core of your question, how do Brazzers and Digital Playground make money when their porn is "freely" available on PornHub and Redtube? Well, partly from those referral sales I was mentioning before. Broadening up the question, that works for most of the companies out there. But when it comes to Brazzers and Digital Playground there is something else worth noting. Those two film studios are functional to the PornHub and RedTube's business model and as long as those tubes earn money the companies are just fine. The reason for this is easily explained.Do you remember Mindgeek owning Brazzers and Digital Playground? Well, Mindgeek owns also PornHub and RedTube. And YouPorn and Tube8 and Xtube and Sextube and many many more. They own all the major porn tubes online except for Xvideos and Xhamster. The main line of business of Mindgeek is porn tubes, not adult film studios. The adult film studios are functional to the tubes and Mindgeek have acquired or got involved with most of the major film studios around, so that they can profit to the expense of smaller studios. The Mindgeek business modelThe tube features free porn. Some of this free porn is legit, some other is stolen copyrighted material. The tube's owners acquire legitimate, important, major film studios. They flood the tube with legitimate content from their just acquired studios and they capitalize on traffic through affiliations, advertising and the sale of sensitive data. This works like a charm and I wouldn't have much to object, as long as the law allows it, if it wasn't for the fact that the tube remains filled with stolen copyrighted content. This is why I didn't want to generalize the answer much and instead i focused on the questions' details. Brazzers and Digital Playground make money, because their mother company Mindgeek makes money or, if you prefer, because PornHub and RedTube make money. They are tools to add legitimate, quality free content to the tube and keep the traffic numbers high; of course a big chunk of that traffic is returned to the studios websites, benefiting their sales volume as well. The real victims and the infamous DMCAIt's all the rest of the industry that suffers from the, often illegitimate, availability of free porn, though. There is so much copyright infringement on porn tubes that you cannot even imagine. Back in 2010 Ventura, owners of the big production studio Pink Visual, filed a lawsuit against Mindgeek for numerous copyright infringements. In the suit the company, among others, stated [1]:These Tube Sites maintain the fiction that they offer a forum for consumers to upload and share their own original ‘user-generated’ adult video content; however in reality, they function as repositories for an extensive collection of infringing adult videos.The suit was settled later that year and the terms of the settlement haven't been disclosed [2]. Whatever convinced Ventura to drop the case, it is obvious that smaller producers don't have either the tools or the money to force tubes to comply with take-down notices. I know this too well. If an hypothetical Mr. Smith uploads a scene of mine stolen from my website to a porn tube, this is going to be the best possible scenario before me:First, I have to discover that a video of mine has been uploaded illegally to a tube. This is very hard because there are thousands of tubes out there and each, especially the major ones, feature hundreds of thousands of videos. I am supposed to monitor all the tubes out there 24/7 checking every new upload. Impossible. All I can do is to check from time to time and to hope to get lucky enough to spot my video if the offender has used some title or description terms that sound familiar to me. Often, if ever, I can spot an illegal upload after weeks, if not months; let's assume that for once i get particularly lucky and that i spot a copyright infringement one week after the video has been uploaded and running. Now I have to let the tube know and file a take-down notice according to the Online Copyright Infringement Liability Limitation Act (aka DMCA). If the video was on PornHub, this is what I have to send:Identification of the copyrighted work you believe to have been infringed or, if the claim involves multiple works, a representative list of such works.Identification of the material you believe to be infringing in a sufficiently precise manner to allow us to locate that material. If your complaint does not contain the specific URL of the video you believe infringes your rights, we may be unable to locate and remove it. General information about the video, such as a channel URL or username, typically is not adequate. Please include the URL(s) of the exact video(s).Adequate information by which we, and the uploader(s) of any video(s) you remove, can contact you (including your name, postal address, telephone number and, if available, e-mail address).A statement that you have a good faith belief that use of the copyrighted material is not authorized by the copyright owner, its agent or the law.A statement that the information in the written notice is accurate, and under penalty of perjury, that you are the owner, or an agent authorized to act on behalf of the owner, of an exclusive right that is allegedly infringed.Complete complaints require the physical or electronic signature of the copyright owner or a representative authorized to act on their behalf. To satisfy this requirement, you may type your full legal name to act as your signature at the bottom of your complaint.Assuming that once I have filed the complaint the company goes through it and acts withing 72 hours, they will contact the offender who may or may not appeal sending a counter-notification within 10 days[3]. If my luck holds and they don't appeal, ten more days have passed and the offending content is finally taken down. For twenty days my stolen content has been made available on a high traffic website and downloaded by thousands of people. By this time it has already been uploaded back to other tubes, if not to the same one as Xbiz journalists Stephen Yagielowicz & Rhett Pardon explain well:For example, one shady scenario involves a company that knowingly and willingly submits infringing content to its tube site — or pays others to do it for them — under the guise of “user” uploads. Then in an effort to seemingly comply with the DMCA, removes clips on request — only to have the compliance department send the removed material to the upload department, where this cynically cyclical process is endlessly repeated. [4] [5] You've got the picture: the big majority of content producers get their content stolen and they lose money while feeding the tubes' traffic despite themselves; part of this traffic is redirected to Brazzers and Digital Playground to finance their big productions; their scenes are leaked back into the tubes, which are owned by the same company, to feed even more traffic;the tubes cash in;rinse and repeat.ConclusionIt is worth noting that ironically this business model has started playing against its own creators. In late 2015, Mindgeek has filed an infringement lawsuit against Xvideos' (one of the only two major adult tubes players not owned by Mindgeek) parent company for allegedly streaming its content "in excess of 100 million times without authorization" and seeking $150,000 for each infringed film which Mindgeek estimate to be in the range of tens to hundreds of thousands[6]. Although the copyright infringements over my content in various tubes relate to only a few tens of videos, this scenario makes me a potential multi millionaire. Today's virtual drinks are on me, fellow Quorans. And if you want real drinks, make sure you pay the producers and not the tubes, when you look for porn. This of course stands for any copyrighted material, including, among others, Hollywood movies, books, software and music.Footnotes[1] "Tube Sites" Threaten Porn Studios[2] Pornhub[3] Online Copyright Infringement Liability Limitation Act[4] The Porn Industry Is Being Ripped Apart By Piracy-Fueled 'Tube' Websites[5] DMCA: The Porn Industry’s Worst Nightmare[6] MindGeek Is Both Plaintiff And Defendant In Two New DMCA Lawsuits
-
Why has NASA not landed at the poles of Mars, or even sent the Curiosity rover there to sample the ice suspected to be there?
It is not lack of interest. The polar regions are of great interest, for instance the Martian dry ice geysers in Richardson crater, one of the most interesting dynamic processes on Mars and the polar regions also have astrobiological interest too. There are potential habitats there that might even have fresh liquid water within 20 cms of the surface of the ice - of all things to find on Mars with its near vacuum atmosphere.As far as I know the only suggested habitats that might have fresh water on Mars are in polar regions, a layer of fresh water only a few cms thick, 10 to 20 cms below the surface in transparent ice. Thin though that layer may be by Earth standards, it is of extraordinary interest on Mars where any fresh water on the surface would evaporate almost immediately. It is a process that happens beneath clear ice in Antarctica and models show it should happen in the Martian ice sheets too, so long as there is similarly clear ice there.The main potential habitats, which I’ll look at in detail in this answer, are:Flow like features in Richardson Crater that form after the Martian dry ice geysers have erupted (not the same as the ones in the northern hemisphere or the ones in Russell’s crater - there are three different similar looking features that form in different conditions - only the ones in Richardson Crater are of special interest for astrobiology)Liquid water forming around sun warmed grains in snow or icePerchlorate salts lying on layers of ice forms liquid water droplets in tens of minutesLiquid water can exist permanently below 600 meters of ice (100 meters of rock) kept warm by the heat of Mars itself, if it once forms, e.g. after an impactIce fumaroles can mask the heat signature of venting of hot moist gas and make good habitatsAnywhere there is clear ice in polar regions, then fresh liquid water can form at a depth of around 6.5 cms by the solid state greenhouse effect.So it’s exciting for astrobiology, also for geology too, but they are also habitats the Earth microbes could contaminate and by the Outer Space Treaty we have an obligation to prevent “harmful contamination” in the words of the treaty. It also just makes sense. If you are searching for native life on Mars, and most people agree that is one of our top science objectives there, the last thing you want to do is to just find life you brought there yourself.So, before we developed this modern understanding of the potential vulnerability of the polar regions to Earth microbes, NASA made two attempts, the Mars Polar Lander which crashed, and Phoenix which succeeded. However it was as a result of unexpected observations by Phoenix that scientists were lead to the realization that actually there could be habitats there for modern native Mars life - and so since then any landers sent there have to be sterilized to a high standard.We could not send Curiosity there, or a second copy of Phoenix either, because it is now not thought to be sterilized sufficiently. Hopefully it has not contaminated the region of Mars around it with Earth life, but I think the Phoenix landing site might be a great site to visit to get ground truth on how effective our planetary protection measures have been on Mars - but with an appropriately sterilized lander of course.WHY IT IS HARD TO STERILIZE TO THE LEVELS OF THE VIKING MISSIONS IN THE 1970SThe current “gold standard” for Mars is set by the Viking landers.Viking Lander being prepared for dry heat sterilization – this remains the "Gold standard" of present-day planetary protection.After preliminary cleaning similarly to the levels used for Curiosity, they were then heat-treated for 30 hours at 125 °CFive hours at 125 °C would be enough to reduce the population of microbes by ten, so this was enough for a millionfold reduction - that’s including enclosed parts of the spacecraft. It would still have a maximum of 30 spores and so several thousand dormant microbes as the spore count used undercounts the number present by a factor of a hundred or so. But in addition the numbers are reduced by the journey out there, the harsh conditions on Mars, and then a microbe would have to be pre-adapted to the conditions there to have a chance of surviving once there.They didn’t achieve certainty but to a high chance no microbe from Viking was able to replicate and spread on Mars.According to modern planetary protection rules then you could send a spacecraft sterilized like this to the Phoenix landing site.But the problem is that modern equipment is much more miniaturized than for Viking, and made up of thin layers only a few atoms thick and delicate materials including epoxy attachments. Even when space hardened, it tends to be more sensitive and so would not stand being baked in an oven for days like Viking. The components would come unglued and instruments also would go out of alignment.WE HAVE ALSO MADE GREAT PROGRESS IN HIGH TEMPERATURE INSTRUMENTS SINCE VIKINGIt’s not all bad news however, for heat sterilization. Since Viking, while commercial equipment for most purposes have got more sensitive to high temperatures, we have also had many advances in high temperature technology too. The commercial equipment is not built to withstand high temperatures not because it can’t be, but because it doesn’t need to be.High temperature electronics and instruments are used where they are needed and are more capable than in the 1970s. We have them for oil wells as they drill deeper to regions where the temperatures go above 200 C. For planes where they can reduce weight by putting sensors closer to the engines, and for electric cars for similar reasons.NASA has also been working for some time to develop a rover able to withstand Venus surface conditions and drive around and study the surface. With high temperatures, high pressures and sulfuric acid too. Very sterilizing for Earth life.In 2007 they developed a silicon chip capable of 17,000 hours of continuous operation at 500 °C.For their Venus rover, we need cameras to operate at high temperatures, we need mechanisms, we need instruments such as a Raman spectroscopy, we need communications and so on. In their 2010 study they thought all of those were possible for the future. Though they couldn’t build it yet, they saw a way to it as a future roadmap.If the aim is to signNow a high temperature for sterilization, the job may be easier to some extent, as the instruments don’t have to actually function at those high temperatures. They have to withstand being heated to high temperatures for a considerable period of time - but will then operate at normal temperatures.So, if you choose the right components for your lander / rover, we actually have the capability to go beyond what they could in the 1970s and I do think that if we went all out with a major program, as for the Venus rover - that we could design a 100% sterile lander in the near future. It would probably need to use RTGs for the power source - and perhaps also as the heat source for sterilization during the journey to Mars, as these have no problem working at high temperatures. Heat your lander at 500 C for six months on the voyage out to Mars and there would be no life left on it at all. Nothing viable. You can also use techniques like CO2 snow which could be done on the surface of Mars to remove even the dead organics from the outside of the lander.There is one plan already for a sterile probe to descend into the Europan ocean by Brian Wilcox.I think myself that designing a 100% sterile rover / lander should be a top priority. It would be expensive to start with, but well worth it.Once we have built the first one and developed the understanding we would have a basic design there that could be used to explore regions such as the subsurface oceans of Europa and Enceladus and the senstiive sites on Mars even if they have cms thick liquid water or more, and yet not have any concerns about introducing Earth life.The long term pay off would be huge.It would obviously take a lot of ingenuity for the astrobiologists, to redesign instruments to be able to be heat sterilized. They did however succeed for Viking, at the temperatures used there. With the Viking sterilization, tenfold reduction every 5 hours, at a dry heat of 125 °C, in theory you wouldn’t need to continue for that long to have pretty much 100% certainty that there is no life left at all.If anyone knows of any work on this apart from Brian Wilcox’s proposed mission, do say!CURRENT PLANETARY PROTECTION RULESAnyway the current rules are not as strict as that. But they do require a lander to be sterilized to Viking levels or higher if they target regions where there is ice within 5 meters of the surface. The reasoning is that a crash could end up melting the ice.So first here is a map of special regions as updated in 2016, but they also decided that even outside of those regions you need to do case by case studies before landing there.There Are Regions On Mars That It's Forbidden To ExplorePOTENTIAL FOR LIQUID WATER HABITATS IN THE POLAR REGIONS - CALCIUM PERCHLORATE SALTS IN LAYERS ON TOP OF ICEDespite what other answers say here, polar regions do have the potential for liquid water. Even fresh, not salty, water.First the Phoenix lander actually spotted droplets forming on its legs.Unfortunately, it wasn't equipped to analyse them but the leading theory is that these were droplets of salty water. They were observed to grow, merge, and then disappear, presumably as a result of falling off the legs.Nilton Renno, who was on the team for Phoenix and also runs the REM “weather station on Mars” for Curiosity was one of several who investigated various ways for thse droplets to form.He found that liquid water can form very quickly on salt / ice interfaces when the salt is on top of the ice. By “salt” there he means calcium perchlorate salts similar to the salts they found in the Phoenix site.Within a few tens of minutes this salt on top of ice formed droplets of liquid brines in Mars simulation experiments. This is striking as it could open large areas of Mars up as potential sites for microhabitats that life could exploit. The professor says"If we have ice, and then the salt on top of the ice, in a few tens of minutes liquid water forms. Our measurements clearly indicate that. And it's really a proof that liquid water forms at the conditions of the Phoenix landing site when this salt is in contact with the ice. "Based on the results of our experiment, we expect this soft ice that can liquefy perhaps a few days per year, perhaps a few hours a day, almost anywhere on Mars. So going from mid latitudes all the way to the polar regions." This is a small amount of liquid water. But for a bacteria, that would be a huge swimming pool - a little droplet of water is a huge amount of water for a bacteria. So, a small amount of water is enough for you to be able to create conditions for Mars to be habitable today'. And we believe this is possible in the shallow subsurface, and even the surface of the Mars polar region for a few hours per day during the spring."(transcript from 1:48 onwards)That's Nilton Renno, who lead the team of researchers. See also Martian salts must touch ice to make liquid water, study shows . He is a mainstream researcher in the field - a distinguished professor of atmospheric, oceanic and space sciences at Michigan University. For instance, amongst many honours, he received the 2013 NASA Group Achievement Award as member of the Curiosity Rover " for exceptional achievement defining the REMS scientific goals and requirements, developing the instrument suite and investigation, and operating REMS successfully on Mars" and has written many papers on topics such as possible habitats on the present day Mars surface.MOHLMANN’S FRESH WATER FORMING AROUND DUST GRAINS IN SNOW OR ICEThis is another suggested habitat for life in the Mars higher latitudes based on processes that happen in the Antarctic ice. Dust grains in the ice often produce tiny melt ponds around them in the heat of the summer sunshine. The dust grains absorb the heat (preferentially over the ice), and so heat up and melt the surrounding ice. Then this heat gets trapped because of the insulating effect of the solid state greenhouse effect, because ice traps heat radiation, so forming tiny melt ponds of a few millimeters thickness or more. This could happen on Mars too, so is another possible habitat with fresh water.It's just a few millimeters of fresh water, but that could be signNow on Mars. Another example of this process, then meteorites in Antarctica are often found associated with gypsum and other evaporates - minerals that can only form in the presence of liquid water and must have formed after they fell in Antarctica. Sometimes the researchers find capillary water, or thin films of water, and sometimes they even find evidence of a rather large meltwater pond which formed around the meteorite, or find the meteorites in depressions filled with refrozen ice.A similar process could be at work in the Martian icecaps too. This process could melt the ice for a few hours per day in the warmest days of summer, and melt a few mms of ice around each grain. Indeed, if I can venture a speculation of my own, perhaps just as in Antarctica, there could be larger melt ponds around meteorites embedded in the ice too - as Mars must have many meteorites embedded in the polar ice sheets.This could explain another puzzle. Particles of gypsum (the same material that is used to make plaster of paris) have been detected, first in the Olympia Undae dune fields that circle the northern polar ice cap of Mars, See this paper for details. Later on, they were detected in all areas where hydrated minerals have been detected, including sedimentary veneers over the North polar cap, dune fields within the polar ice cap, and the entire Circumpolar Dune Field. There's strong evidence that the gypsum originates from the interior of the ice cap. See this paper for details. Gypsum is a soft mineral that must have been formed close to where it has been discovered (or it would get eroded away by the winds) and as an evaporite mineral, it needs liquid water to form. Opportunity later found veins of gypsum in the equatorial regions, in 2011, a clear sign of flowing water on ancient Mars. But these polar deposits are more of a mystery because they are found in the dust dunes on Mars, so must be produced locally, but where?.Losiak, et al, modeled tiny micron scale dust grains of basalt (2-2 microns in diameter) exposed to full sunlight on the surface of the ice on the warmest days in summer, on the Northern polar ice cap. They found that these tiny dust grains were large enough to provide for five hours of melting which could melt six millimeters of ice below the grain. They say that with pressures close to the triple point, on windless days, you should get a signNow amount of melting. They speculate that this might possibly explain the deposits of gypsum in the polar regions. Could it have formed in a similar way to the gypsum that sometimes forms around Antarctic meteorites?Möhlmann did a similar calculation. This time he was looking at the possibility of liquid water forming inside snow on Mars. The snow would be exposed to the vacuum, but as the ice melted it would plug all the pores in the snow and eventually form a solid crust of ice on the snow, and so protect it from further evaporation. It would trap the heat as well and so encourage melting. This could happen anywhere between a few centimeters depth down to ten meters below the surface.THIN FILMS OF UNDERCOOLED WATER WRAPPED AROUND INDIVIDUAL MICROBESThis is an interesting suggestion by Möhlmann in an article in Cryobiology magazine, that life may be able to make use of thin film monolayers of the " ULI water" (Undercooled Liquid Interfacial water) wrapped around a microbe, even in tiny nanometer scale layers of liquid water only two monolayers thick."In view of Mars it should be mentioned, that there is water ice in the permanent polar caps. At mid- and low-latitudes, ice can form, at least temporarily, via adsorption and freezing in the soil. There, the adsorbed and frozen water overtakes the role of ice, as described above. So, ULI-water can be expected to, at least temporarily, exist also in martian mid- and low-latitudinal subsurface soil. A similar environment can be expected to exist in isolation heated parts of icy bodies in the asteroidal belt, and analogously in the internally heated icy moons of Jupiter and Saturn. It is thus a current and challenging question if ULI-water can act as supporting life in environments with temperatures clearly below 0 °C by delivering that water, which is necessary for metabolic processes, and by permitting transport processes of nutrients and waste. It is the aim of this paper to demonstrate the potential importance of ULI water in view of the possible biological relevance of nanometric undercooled liquid interfacial water."He cites research suggesting life can remain active in the presence of just two monolayers of water wrapped around a microbe.If there is just a small thermal gradient in the ice, of one degree centigrade per meter, then enough liquid water will form to fill a micrometer sized microbe once a month. Enough will form to fill it once a day if there is a locally steeper gradient of one degree centigrade per 10 cm. This can lead to a constant transport of fresh water to bring fresh nutrients to the microbe, and to remove wastes. The main question is whether this is a sufficient flow of water to sustain life. For more details of this intriguing idea, see his article.SOUTHERN HEMISPHERE FLOW-LIKE FEATURES - MAY INVOLVE FRESH WATER CMS THICK!There are two main types of these flow-like features. For a technical overview of them, see the Dune Dark Spots section in Nilton Renno's survey paper. These ones in the southern hemisphere which form in Richardson crater are particularly promising because all the current models involve liquid water in some form and what's more, in the models, these features start off as fresh water trapped under ice.The more interesting ones, for habitability, are in the south. The southern ice cap consists mainly of dry ice. It is colder, and higher up (at a higher altitude). It stretches as far as forty degrees from the pole in winter (so spanning over 4,700 km), but it reduces to just 300 km across in summer, Richardson's crater is 17.4 degrees from the south pole (that's over 1,000 km).So though the features resemble each other in appearance, the conditions in which they form are very different and not directly comparable. The southern hemisphere features from at much higher surface temperatures than the northern hemisphere features, and they appear late in spring, after the rapid disappearance of a vast and thick layer of dry ice that covered the entire southern polar region, and beyond. In the summer then surface temperatures at Richardson crater can actually get above the melting point of ice at times in daytime, as measured by the Thermal Emission Spectrometer on Mars Global Surveyor. (See figure 3 of this paper)..This map shows where the crater is. It is close to the south pole - this is an elevation map showing the location of Richardson crater in Google Mars, and I’ve trimmed it down to the southern hemisphere. You can see Olympus Mons as the obvious large mountain just right of middle, and Hellas Basin as the big depression middle left. Richardson crater is about half way between them and much further south.Here is a close up - see all those ripples of sand dunes on the crater floor?Link to this location on Google MarsWell it’s not the ripples themselves that are of special interest, Mars is covered in many sand dune fields like that planet wide. What interests us are some tiny dark spots that form on them which you can see if you look really closely from orbit.And, would you ever guess? Although it's one of the colder places on Mars, there's a possible habitat for life there in late spring? It is due to the "solid state greenhouse effect" which causes fresh water at 0°C to form below clear ice in Antarctica at a depth of up to a meter, even when surface conditions are bitterly cold.The Warm Seasonal Flows often hit the news (probable salty brines on sun facing slopes). But for some reason, the flow-like features in Richardson crater are only ever mentioned in papers by researchers who specialize in the study of possible habitats for life on Mars.I first learnt about them in the survey of potential habitats on Mars by Nilton Renno, who is an expert in surface conditions on Mars (amongst other things, he now runs the Curiosity weather station on Mars). You can read his survey paper here, Water and Brines on Mars: Current Evidence and Implications for MSL. The models I want to summarize here are described in his section 3.1.2 Dune Dark Spots and Flow-like Features under the sub heading "South Polar Region". But it's in techy language so let's unpack it and explain what it means. I will also go back to the papers he cited, and some later papers on the topic.In the case of Richardson's crater, both models involve liquid water in some form, and also potentially habitable liquid water. One of the two main models involves relatively thick layers of fresh water below optically clear water ice, up to tens of centimeters thick, and so is very promising for microhabitats. The other model involves microscopically thin layers of fresh water that join together to make a larger stream and pick up salts on the way out. That's very promising too. So let's now look at these two ideas in detail.First, early in the year, you get dry ice geysers - which we can’t image directly, but see the dark patches that form as a result and are pretty sure this is what happens:Geysers which erupt through thick sheets of dry ice on Mars. Clear dry ice acts as a solid version of the greenhouse effect, to warm layers at the bottom of the sheet. It is also insulating so helps keep the layers warm overnight. Dry ice of course at those pressures can't form a liquid, so it turns to a gas and then explosively erupts as a geyser. At least that's the generally accepted model to explain why dark spots suddenly form on the surface of sheets of dry ice near the poles in early spring on Mars.So that would be cool enough, to be able to observe them, video them and study them close up. I hope the rover would be equipped with the capability to take real time video. These geysers are widely known and many scientists would tell you how great it would be to look at them up close, and see them actually erupt.But most exciting is what happens later in the year, when it is getting too warm for the thick layers of dry ice needed for geysers. These layers of dry ice vanish rather quickly in spring. You would think that the dark spots that you get in the aftermath of the geysers would just sit there on the surface and gradually fade away ready to repeat the cycle next year. But no. Something very strange happens. Dark fingers being to form and creep down the surface as in this animation. Very quickly too (for Mars). I haven't been able to find a video for this, as the papers just use a sequence of stills, so I combined together some of the images myself into an animation to show the idea:Flow-like features on Dunes in Richardson Crater, Mars. - detail. This flow moves approximately 39 meters in 26 days between the last two frames in the sequenceAll the likely models for these features, to date, involve some form of water. Alternatives that one might try to use to model them might include a second ejection of material by the dry ice geyser, or dust deposition, but researchers think these are unlikely to produce the observed effects.SIMILAR LOOKING FEATURES NOT TO BE CONFUSEDThe Richardson crater flow-like features should not be confused with two rather similar looking features, the dark streaks in Russell crater, 55 degrees from the south pole (compared to 17.4 degrees for Richardson crater).These are braided, divide, recombine and cross each other's tracks. They flow down the slopes channeled by wind formed ridges in the dunes, and most distinctive of all, they are able to rush up over small features of up to two meters high and down the other side.These seem to be dry features associated with defrosting and small dust avalanches as they are episodic, moving rapidly at speeds of 2-4 meters per second like an avalanche. The authors call them "dark flows". For details see this paper.They also should not be confused with the Flow-like features in the Northern polar dunesThe two Martian ice caps are rather different. The northern cap is low lying, mainly ice, with a thin layer of dry ice that disappears in summer. The flow like features in the northern hemisphere form at 12.5 degrees from the pole at surface temperatures of about -90°C, which is low enough for dry ice to be stable on the surface. Their models involve either extremely cold salty brines or dry ice and sand. These features are far too cold to be habitable to Earth life and may not even involve liquid waterThey are easily confused because they are so similar in appearance, and because both are referred to as "flow like features".These are thought to form at much lower temperatures. Some of the models for these also involve liquid water but there are other hypotheses as well, some of them involving dust and ice slipping down the cliff faces.Perhaps one reason the Richardson crater flow-like features get so little attention is that it is easy to confuse them with these other features and assume they have been proved to be dust flows or to form at temperatures to low to be habitable.But they form in different conditions at different temperatures and the explanations used for these other features don’t work for them. Currently the only models for them involve fresh liquid water beneath the ice, either as layers cms thick, or as thin undercooled liquid water layers, then combining with salts to form the flows on the Martian surface.MORE ABOUT THESE FEATURES AND WHY THEY ARE SO INTERESTING FOR HABITABILITYSo, these southern hemisphere flow like features seem very promising. That’s not as surprising as you might think. The same thing happens in Antarctica - if you have clear ice, then you get a layer of pure water half a meter below the ice.The water is trapped by the ice so stays liquid. And what’s more, if they model it assuming clear ice like the ice in Antarctica they find that the ice there gets enough heat from the sun in the day to keep it liquid through the night to the next day so the layer can actually grow from one day to the next (ice is an excellent insulator). Also the Mars atmosphere is so thin that it doesn't matter at all that the air above the ice is very cold in these regions. The atmosphere is a near vacuum and works as a great insulator. Better in some ways than Antarctica.Inuit village, Ecoengineering, near Frobisher Bay on Baffin Island in the mid-19th century - ice and snow are very insulating on Earth or on Mars. Just as you can be snug and warm inside an igloo, a layer of fresh water can stay warm a few tens of cms below the surface, warmed by the sun every day beaming through th clear ice. The near vacuum of the Mars atmosphere helps if anything.Möhlmann's model is pretty clear (abstract here). If Mars has transparent ice like the ice in Antarctica, then it should have layers of liquid fresh water 5 - 10 cm below the surface and a couple of cm in vertical thickness in late spring to summer in this region. His model doesn't involve salt at all, so the water would be fresh water.The only question here is whether clear ice forms on Mars in Mars conditions and whether the ice is sufficiently insulating. We can’t tell that really from models, the only way is to go there and find out for ourselves.Blue wall of an Iceberg on Jökulsárlón, Iceland. On the Earth, Blue ice like this forms as a result of air bubbles squeezed out of glacier ice. This has the right optical and thermal properties to act as a solid state greenhouse, trapping a layer of liquid water that forms 0.1 to 1 meters below the surface. In Möhlmann's model, if ice with similar optical and thermal properties forms on Mars, it could form a layer of liquid water centimeters to decimeters thick, which would form 5 - 10 cm below the surface.In his model, first the ice forms a translucent layer - then as summer approaches, the solid state greenhouse effect raises the temperature of a layer below the surface to 0°C, so melting it.The melting layer is 5 to 10 cm below the surface. In the model, then the ice below the surface is first warmed up in the daytime sunshine, due to a greenhouse effect, the infrared radiation is trapped in the ice in much the same way that carbon dioxide traps heat to keep Earth warm. Then because the ice is so insulating, the heat is retained overnight, and the water remains liquid to the next day. To start with it would be only millimeters thick but over several days, gets to thicknesses of centimeters.He found that subsurface liquid water layers like this can form with surface temperatures as low as -56°C.CREATES POTENTIAL FOR FRESH LIQUID WATER FLOWING ON MARS!This should happen on Mars so long as it has ice with similar properties to Antarctic clear ice.If there is a layer of gravel or stone at just the right depth, the rock absorbs the infrared heat and that can speed up the process. In that case, a liquid layer can form within a single sol, and can evolve over several sols to be as much as several tens of centimeters in thickness. That is a huge amount of liquid water for the Mars surface.The fresh water of course can't flow across the surface of Mars in the near vacuum conditions, as it would either freeze back to ice, or evaporate into the atmosphere. But the idea is that as it spreads out, it then mixes with any salts also brought up by the geyser to produce salty brines which would then remain liquid at the much lower temperatures on the surface and flow beyond the edges to form the extending dark edges of the flow-like features.Later in the year, pressure can build up and cause formation of mini water geysers which may possibly explain the "white collars" that form around the flow-like features towards the end of the season - in their model this is the result of liquid water erupting in mini water geysers and then freezing as white pure water iceThis provides:A way for fresh water to be present on Mars at 0 °C, and to stay liquid under pressure, insulated from the surface conditions.5 to 10 cm below the surface, trapped by the ice above itDepending on conditions, the liquid layer is at least centimeters in thickness, and could be tens of centimeters in thickness.Initially of fresh water, at around 0°C.They mention a couple of caveats for their model, because the surface conditions on Mars at these locations is unknown. First it requires conditions for bare and optically transparent ice fields on Mars translucent to depths of several centimeters, and it's an open question whether this can happen, but there is nothing to rule it out either. Then, the other open question is whether their assumption of low thermal conductivity of the ice, preventing escape of the heat to the surface, is valid on Mars.The process works with blue ice on Earth - but we can't say yet what forms the ice actually takes in these Martian conditions. The authors don't go into any detail about this, but ordinary ice can take different forms even in near vacuum conditions. As an example of this, the ice at the poles of the Moon could be "fluffy ice""We do not know the physical characteristics of this ice—solid, dense ice, or “fairy castle”—snow-like ice would have similar radar properties. [then they give evidence that suggests fluffy ice is a possibility there] " (page 13 of Evidence for water ice on the moon: Results for anomalous polar)That's the main unknown in their model, whether the ice is blue ice like Antarctic ice, or takes some other form. The ice should at least be in the same hexagonal structure crystalline phase as ice is on Earth - Mars is close to the triple point in this ice phase diagramPhase diagram by Cmglee, wikipedia. Ice outside of Earth can be in many different phases. For instance in the outer solar system it is often so cold that it is in the very hard orthorhombic phase, where it behaves more like rock than what we think of as ice. However ice on Mars is likely to be in the Ih phase similar to Earth life. The Mars surface is close to the triple point of solid / liquid / vapour in this diagram. So, the ice is likely to be of the same type as the blue ice in Antarctica. Not likely to have bubbles of air in it. But it could still take a different forms. The model shows that Mars should have layers of liquid water ten to twenty centimeters below the surface if there are any areas of clear blue ice as in Antarctica.This solid state greenhouse effect process favours sun facing slopes (equator facing). Also, somewhat paradoxically, it favours higher latitudes, close to the poles, over lower latitudes, because it needs conditions where surface ice can form on Mars to thicknesses of tens of centimeters. (The examples at Richardson crater are at latitude -72°, longitude 179.4°, so only 18° from the south pole. There is no in situ data yet for these locations, of course, to test the hypothesis. Though some of the predictions for their model could be confirmed by satellite observations.ALTERNATIVE - THIN LAYERS OVER SURFACES MELTING AT WELL BELOW O CAnother model for these southern hemisphere features involves ULI water (Undercooled Liquid Interfacial water) which forms as a thin layer over surfaces and can melt at well below the usual melting point of ice. In Möhlmann's sandwich model, then the interfacial water layer forms on the surfaces of solar heated grains in the ice, which then flows together down the slope. Calculations of downward flow of water shows that several litres a day of water could be supplied to the seepage flows in this way.The idea then is that this ULI water would be the water source for liquid brines which then flow down the surface, mixing with dust, to form the features. That would still be interesting as you end up having flowing liquid water on Mars, several litres a day what’s more. Here is a paper from 2016 describing the idea.See also Möhlmann's paper The three types of liquid water in the surface of present MarsThose are the only two models so far. So it does seem very likely that there is liquid water here, and even with the interfacial liquid layers, the water starts off as fresh water beneath the ice, or possibly salty (in either model) if there are salt grains in the ice for the water to pick up. Either way the features start out as a flow of fresh water trapped beneath a layer of ice. This is one of the least publicized types of habitat on Mars, seldom mentioned outside the specialist literature. Yet in some ways it's one of the most interesting, if it exists, because of the potential for fresh water at 0 °C.This liquid water is hard to observe because the features are so small, beyond the resolution of CRISM. However, analysis of the larger spots, at around the spring equinox, produced a signal that just possibly could be liquid water, where the ice is in contact with the dark material of the dune spots." In the gray ring area the water ice 631 surrounds darker surface, where liquid interfacial water layer or brine (Möhlmann 2004, 632 2009, 2010) may form. We found no firm evidence for the presence of liquid water in near-IR 633 spectra, although linear unmixing results show that the data are not inconsistent with a 634 possible slight contribution (a few %) of liquid water in the dark core unit." page 26 of this paper.MORE WIDESPREAD LIQUID WATER AT DEPTH OF ABOUT 6.3 CM BELOW OPTICALLY CLEAR ICEMöhlmann has also suggested that his process could be a more widespread phenomenon in the Mars ice caps, not just associated with the geysers, as for Antarctica. Just more noticeable for the flow-like features because of the conditions in which it forms there.Liquid water could form at a depth of around 6.3 cm wherever there is optically clear ice on Mars in snow / ice packs, just as it does in Antarctica. In summer, it could form layers from centimeters to tens of centimeters in thickness.Results of Mohmann's modeling of the solid state greenhouse effect in clear ice on Mars. The plateaus show temperatures that get above the melting point of water regularly every Martian sol, at depths of about 6.3 cms. L here is 11.4 cm. Ice at this level will melt periodically, and especially in summer can stay liquid overnight, leading to subsurface liquid water in layers of from cms to tens of cms in thickness. This should happen on Mars not just in the flow-like Features of Richardson crater, but also, anywhere where there is optically clear ice.In another paper he writes "This liquid water can form in sufficient amounts to be relevant for macroscopic physical (rheology, erosion), for chemical, and eventually also for biological processes. "His models seem clear enough. The air temperature hardly matters, because the Mars air is so thin it's a near vacuum, insulating the ice, like a thermos flask. The only unknown here is whether Mars does have optically clear ice like this, which is common on Earth in cold conditions like this in Antarctica.Before I go on to the last couple of examples of possible habitats in the polar regions, let’s just revisit the Phoenix lander site. I think it would be a great place for a mission that’s both interesting for astrobiology and also for ground truth for planetary protection.LIFE IN ICE TOWERS HIDING VOLCANIC VENTSSo, this is another suggestion, that we could find habitats on Mars inside ice fumaroles. It's a nice idea, and perhaps ice fumaroles do form on Mars from time to time. So far we haven't found any on present day Mars. But it may well be worth keeping a look out for them, as it would be a very interesting habitat if we find one, or one of them starts to form, around a volcanic vent on Mars. If Mars does have any volcanic vents which vent water rich gases through a fumarole, they are likely to form ice towers like this, as happens in Antarctica.Let's look at the idea in some more detail. This photo shows an ice fumarole - an ice tower that forms around a vent of volcanic gases in the extremely cold conditions right near the top of Mount Erebus in Antarctica.+ One of the numerous Ice Fumaroles near the summit of Mount Erebus in Antarctica. If these also occur on Mars, they could provide a habitat for life, and would be extremely hard to spot from orbit due to the low external temperatures. Image credit Mount Erebus Volcano ObservatoryFor more photos of ice fumaroles see "Ice Towers and Caves of Mount Erebus",They were originally discovered by the Antarctic explorer Shackleton during his 1908 Nimrod expedition, when he and a few others set out to climb Mount Erebus.Photograph from Shackleton's Mount Erebus expedition with a fumarole in the backgroundHe described them like this."The ice fumaroles are specially remarkable. About fifty of these were visible to us on the track which we followed to and from the crater, and doubtless there were numbers that we did not see. These unique ice-mounds have resulted from the condensation of vapour around the orifices of the fumaroles. It is only under conditions of very low temperature that such structures could exist. No structures like them are known in any other part of the world."Ice caves form below the fumaroles, and these are especially interesting as a habitat for life.Entrance to Warren Cave on Mount Erebus. Credit Brian Hasebe. Volcanically heated, the temperatures inside their three study sites were 32, 52 and 64 degrees Fahrenheit (2,11 and 18 degrees Celsius), far warmer than the surroundings.These ice caves on Erebus are of especial interest for astrobiology, as analogues for habitats outside of Earth, because they are so biologically isolated. Most surface caves are influenced by human activities, or by organics from the surface brought in by animals (e.g. bats) or ground water. These caves at Erebus. are high altitude, yet accessible for study. There is almost no chance of them being affected by photosynthetic based organics, or of animals in a food chain based on photosynthetic life. Also there is no overlying soil to wash down into them.As described in this paper, these ice towers eventually collapse and then rebuild themselves, but though temporary features, they persist for decades. The air inside has 80% to 100% humidity, and up to 3% CO2, and some CO and H2, but almost no CH4 or H2S. Many of the caves are completely dark, so can't support photosynthesis. Organics can only come from the atmosphere, or from ice algae that grow on the surface in summer, which may eventually find their way into the caves through burial and melting. As a result most micro-organisms there are chemolithoautotrophic i.e. microbes that get all of their energy from chemical reactions with the rocks. They don't depend on any other lifeforms to survive. They survive using CO2 fixation and some may use CO oxidization for their metabolism. The main types of microbe found there are Chloroflexi and Acidobacteria.This makes them very interesting as an analogue for Mars habitats. If Mars is currently geologically active, then in such cold conditions, it may well have ice fumaroles around its vents, and if so they would be only a few degrees higher in temperature than the surrounding landscape and hard to spot from orbit. We haven't found these yet. The closest we have got so far is that the silica deposits in Home Plate which Spirit found, might have been formed by ancient fumaroles on Mars, (not necessarily ice fumaroles) though they could also have been formed by hot springs or geysers.This article Martian Hot Spots in NASA's Astrobiology magazine presents Hoffman's ideas. He explains that ice fumaroles on Mars could be up to 30 meters tall in its lower gravity and 10 to 30 meters in diameter, circular or oval in shape. So, potentially these things could grow to be huge on Mars, as high as a nine story high skyscraper, and potentially some of them could be as wide as they are high.He suggests searching for them on Mars from orbit, and he wondered if some temperature anomalies in Hellas Basin could be ice fumaroles. They wouldn't need to be in polar regions because the fumaroles themselves would bring large quantities of water vapour to the surface to keep replenishing the ice towers as they sublime away in the thing Mars atmosphere. They might be quite easy to spot as white circles or ovals, probably in permanently shadowed regions, and they would be slightly warmer than their surroundings. This shows one of his candidates.Daytime infrared from Odyssey IRAnomalous warmth in infrared at night as well on all nine infrared bands, so not a chemical signature.That candidate is in Hellas Planitia and is from 2003. Despite a search of high resolution visual images they were unable to find anything visual corresponding to them, they were only visible in infrared. But it shows the sort of thing they would be looking for. Lots of small dots around 10-30 meters in diameter each, clustered around a potential fracture. For details see their paper.The idea is that just as on Earth, volcanic action could bring water vapour and other gases from below. The water vapour, as in Antarctica, would freeze out to form these ice towers. If these environments do occur on Mars, they would provide a warm environment, high water vapor saturation, and some UV shielding. The ones we have on Earth don't have signNow amounts of liquid water. However, as they have close to 100% humidity inside, that doesn't matter. They sustain microbial communities of oligotrophs, i.e. micro-organisms that survive in environments that are very poor in nutrients. The same could be true of Mars.Though we haven't found ice fumaroles on Mars yet, we have found recently formed rootless cones, which are the results of explosive contact of lava with water or ice. This shows that ice (or water) and lava were in close proximity as recently as around ten million years ago.This shows rootless cones on Mars (to the left) and in Iceland. They are the locations of small explosions of steam, when lava surges over the surface over water or ice. These rootless cones on Mars formed around ten million years ago which shows that Mars has had ice and lava in close proximity very recently. They range in diameter from 20 meters to 300 meters.So, could there be other ways that volcanic processes on Mars produce habitats by interacting with ice, such as the ice fumaroles? From this 2007 paper:Hoffman and Kyle suggested the ice towers of Mt. Erebus as analogues of biological refuges on Mars. They combined the idea of still existing near surface ice deposits with the assumption that there is still some localized volcanic activity on Mars today.There are several examples from Mars that show a direct interaction between lava and ice in the geological history of Mars. The most obvious cases are the rootless cones seen in the northern lowlands. HRSC images show direct and violent interaction in the relatively recent geological history, for example at the scarps of Olympus Mons. Mars today is in relatively dormant phase, and any interactions which might be occurring today are presumably on a much less dynamic scale. Nevertheless, they may be driving local hydrothermal systems. Studying the geothermal processes in the first few tens to hundreds of meters below the surface of Mars today might thus uncover a wide variety of new habitats where biological activity may survive on this cold and dry planet.For more about this topic see Volcano-Ice Interaction as a Microbial Habitat on Earth and Mars. These ice fumaroles would be of great interest, but of course, being open to the surface, would easily be contaminated by Earth life from surface explorers or brought in to them through dust from the Martian storms.So far we've been looking at habitats deep below the surface of Mars, though perhaps connected to the surface. But what about habitats on the surface itself? They would make planetary protection even more of an issue, so it's important to look at the possibility. First we need to look at the question, is surface life possible there at all. Just a decade ago, most scientists (with the exception of Gilbert Levin) would have answered with a resounding "No". But that's all changed.There might also be habitats for native Mars life below the surface similar to lake Vostok in Antarctica - well within signNow of drilling. Searches so far have turned up a blank but they could still be there if the lakes are small up ot a few kilometers in size. They could be as close to the surface as only 100 meters deep below rock, or 600 meters deep below ice and remain liquid indefinitelyICE COVERED LAKES HABITABLE FOR THOUSANDS OF YEARS AFTER LARGE IMPACTS - OR INDEFINITELYWhen comet Siding Spring was discovered in 2013, before they knew its trajectory well, there was a small chance that it could hit Mars. Calculations showed it could create a crater of many kilometers in diameter and perhaps a couple of kilometers deep. If a comet like that hit the martian polar regions or higher latitudes, away from the equator, it would create a temporary lake, which life could survive in.Artist's impression of Mars as seen from comet Siding Spring approaching the planet on 9th October 2014. It missed, by less than half the distance to our Moon. But sometimes comets will hit the Mars ice caps or higher latitudes. If that happens, it will create lakes and hydrothermal systems that last for thousands of years.These lakes can last for a surprisingly long time, insulated by the ice and heated from below by the rock. The models suggest that large craters of 100 - 200 km in diameter in the early solar system would have made lakes that stayed liquid for as long as one to ten million years. This happens even in cold conditions, so it is not limited to early Mars. A present day comet a few kilometers in diameter could form a crater 30 - 50 km in diameter and an underground hydrothermal system that remains liquid for thousands of years. The lake is kept heated by the melted rock from the initial impact in hydrothermal systems fed by water from deep underground.Also, there's another way to keep water liquid. Any ice deep enough below the surface, only 100 meters deep, can actually stay liquid indefinitely if covered by an insulating layer of gravel. There'd be enough heat from below, just from the heat of Mars itself and enough insulation above from the gravel, to keep the water permanently liquid. See section 2.2.3 of Niton Renno's article. This is also one theory for the Martian "dry gullies" that they formed through liquid water suddenly flowing out of a subsurface aquifer like this. This was the most popular theory for them at one point, though there are other explanations for them now.It's much harder to keep water liquid below ice, since rock is much more insulating than ice. It's especially hard for water to form below an ice sheet. If the ice cap was four to six kilometers deep, then you'd expect the base of it to be liquid water, melted from below just through the heat of Mars itself. Though Mars does have ice at both poles, its ice sheets aren't quite as deep as that. But it could still have liquid water at the base of its ice sheets, if there's localized geothermal heating from below.Also, if a lake formed, originally by geothermal melting or a meteorite impact, it's much easier to keep the lake liquid than it was to melt the water in the first place. In one model, then if a lake forms at a depth of over 600 meters below the ice (originally open to the surface) then it can remain liquid indefinitely from the heat flux from below, even without local geothermal heating.We'd be able to detect this water using ground penetrating radar because of the high radar contrast between water and ice or rock. MARSIS, the ground penetrating radar on ESA's Mars Express is our best instrument for the job. After several searches, it hasn't found anything yet. See page 191 of this paper. Their resolution isn't that great, however, around a kilometer.From the searches done to date, we can say with reasonable certainty that Mars doesn't seem to have an equivalent of our Lake Vostok (250 km by 50 km by 0.43 km deep) beneath its ice caps at present. It could however still have small subglacial lakes of up to a kilometer or so in diameter. They were looking for water liquid through geothermal heating, but their search would surely have found impact lakes too.So, Mars doesn't seem to have any large lakes created from impacts just now. Nor does it have any major lakes formed through geothermal activity below glaciers or ice caps, though it could have smaller lakes.So in short there are lots of exciting prospects to explore in the polar regions for astrobiologySo far we haven’t even made a start at looking for life there. Or anywhere on Mars except briefly in the 1970s with the Viking landers which produced ambiguous results and have never been followed up.See also myIs This Why We Haven't Found Life On Mars Yet? Value Of Actually LookingLet's Make Sure Astronauts Won't Extinguish Native Mars Life - To Jupiter's Callisto, Saturn's Titan And Beyond - Op EdModern Mars habitability - WikipediaTouch Mars? (book, around 2,000 pages, in a single web page, give it time to load) - this article is based mainly on sections of this bookRemoved section of this answer about the idea of using the Phoenix lander site to test planetary protection ideas - it was long enough anyway and that made it rather long :)
-
Did Steve Jobs get a new Mercedes every 6 months because a car didn't need a license plate until it was 6 months old?
Supposedly he did, but that didn’t absolve him of the responsibility to put license plates on his car. At the time, there were no temporary plates in California. He would not be able to get away with it today.The law at the time gave new car dealers 20 days to do the “paperwork” with the DMV. In all likelihood it was done electronically much sooner, or in his earlier days, within a few days.Once the paperwork was processed, and he received plates, he was required to put the plates on the car. The law did allow for a 90 day period without plates, meaning that it was illegal for him to drive without plates even if he hadn’t received the plates by then. But had he received them earlier, he would have been required to put them on.A police officer would have had no way of knowing by looking at a car whether a person had received plates in the mail or whether the person had bought the car within the past 90 days, and it wouldn’t have been reasonable to pull him over for lack of plates alone. So he was likely taking advantage of the fact that they wouldn’t have known that he was driving illegally rather than of an actual loophole in the law, except perhaps for the first month or so after he bought a new car.If he had been pulled over within the first 90 days, since the paperwork would have shown that it would have been legal to drive without plates had he not yet received them, he wouldn’t have gotten a ticket.Since a given model of car is typically sold for about a year, he probably could have driven without plates for about 18 months without arousing suspicion. If he got a new car the moment it hit the market, then 18 months later there might have been people who had purchased that car new within the past 90 days. Since it would have been illegal to drive without plates once he received them, I can’t see why he would have picked a six month period and attributed any relevance to it.If he had gotten a ticket, it likely would have been for about $65, and could have been reduced to $10 with evidence that he put the plates on the car. That would have required a signature from a law enforcement officer. Interestingly, the form I’ve seen for it from San Francisco asked for a signature and badge number, but not the agency or city. It didn’t even ask for the officer’s name to be printed under the signature. Since it got returned to a clerk whose job it was to process the checks and who had no vested interest in verifying something that couldn’t have been verified, and since he could have gotten it verified legitimately and then removed the plates shortly thereafter, it frankly seems like more work to replace a car every six months than to just pay the fine in full. The likelihood of getting a fine was low enough, and it would have cost more time and money to keep replacing the car than to pay the fine.
-
Is wave-particle duality an illusion?
"Illusion" is an interesting choice of words. To acquire the kind of understanding I think you're after, let's back up a bit and see if we can excavate the foundation of this question. Let me start with a quote. “The voyage of discovery lies not in seeking new horizons, but in seeing with new eyes.” ~ Marcel Proust An examination of the double-slit experiment will give us a good introduction to the mystery you have singled out. But to make that examination worthwhile, we need to make sure that we are familiar with an important effect known as interference. [i]Interference applies universally to all interacting waves. A water wave, for instance, can be described as a disturbance in the shape of the water’s surface. This disturbance produces regions where the water level is higher and regions where it is lower than the undisturbed value. The highest part of each ripple is called a peak and the lowest part is called a trough. Typically waves involve periodic succession, peak followed by trough followed by peak and so on. In general, we can define a wavelength as the distance between identical parts of adjacent waves. Measurements from peak to peak, or trough to trough, for example, give the same value for wavelength.Figure 1 Peaks and troughs of wavesWhen waves interact in a medium, they interfere. For example, if we drop two rocks into spatially separated parts of a pond, their waves will interfere when they cross. (Figure 2) When a peak of one wave and a peak of another wave come together, the height of the water rises to a height equal to the sum of the two peaks. Similarly, when a trough of one wave and a trough of another wave cross, the depression of the water's surface dips to the sum of the two depressions. And when a peak of one wave crosses with a trough of another, the (at least partially) cancel each other out. The peak of one wave contributes a positive displacement while the trough of the other wave contributes a negative displacement. If the two waves have equal magnitude, then there will be perfect cancelation and the water's surface will be flat, just as it was before any wave existed.Figure 12-2 Constructive and destructive interference Keeping these rules of interference in mind, let’s turn our attention to light. If we take a laser emitting a single wavelength—a single color, and shine it on a screen that has a slit etched into it (Figure 3), what image should we expect to see on the wall behind the screen? [ii] Classically speaking, we would expect to see a stripe of light on the wall. (Classically means according to our four-dimensional intuition, or the rules of Euclidean geometry.) It turns out that this is what we see. In this sense light’s behavior correlates perfectly with our Euclidean intuition.Figure 12-3 Expected single slit projectionWhat image should we expect to see on the wall if we etch a second slit on our screen and cover the first slit with a black piece of tape? Well, our classical intuitions tell us to expect a line of light projected on the wall, just like we did before, except this line of light should be offset from the first. Again, this is exactly what we see when we perform the experiment. So far all of this is straightforward and conceptually trivial. But as it turns out, we are only one step away from a profound mystery. We discover this mystery by removing the piece of tape. To understand the impact of this mystery, ask yourself: What sort of projection do we expect to see on the wall when both slits are open?Classical intuition tells us that we should see two parallel bands of light on the wall (Figure 4).Figure 4 Expected double slit projectionBut this is where our classical training (our Euclidean intuition) lets us down. This is also where classical mechanics breaks down. When we perform this experiment, something completely counterintuitive happens, contradicting our Euclidean intuitions. A distinct interference pattern is projected on the wall (Figure 5).Figure 5 Actual double slit projection The bright and dark bands produced in this double-slit experiment are telltale signs that light propagates as a wave. [iii] Interference patterns are key signatures of waves. The problem is that this wavelike characteristic directly clashes with our observations of light’s particulate behavior. After all, photons are always found in point-like regions rather than spread out like a wave, and individual photons are always found to have very discrete amounts of energy. When measuring a wave, you would expect to find its energy spread out over a region instead of being concentrated in one location. So how are we supposed to make sense of this observation? What is going on?These diametrically opposed properties of light are verified facts. Contradictory as they may seem, they are here to stay. They have forced us to the seemingly paradoxical conclusion that light is both a wave and a particle. But how can this be? How can it be both? Although many scientists have found thewave-particle duality of light to be conceptually vague and schizophrenic, this description has persisted. In fact, after the wave-particle concept was adopted as an accurate description of light, it was extended to describe electrons and, eventually, all of matter. This transition was nothing short of a revolution.Up until 1910, atoms were simplistically viewed as miniature solar systems with the nucleus making up the “central star” and orbiting electrons being “planets”. [iv] The wave-particle duality of light and matter rejected this view and pointed to a signNowly different architecture for atoms. Of course, this conceptual transition did not take hold over night.In 1924, Prince Louis de Broglie found that in addition to their particle like character, [v] electrons also possessed a wavelike character. In 1927, Clinton Davisson and Lester Germer followed this up by firing a beam of electrons at a piece of nickel crystal, which acted as a barrier analogous to the one used in the double-slit experiment. A phosphor screen recorded the resultant pattern of electrons. [vi] When they examined the screen, they observed an interference pattern just like the one produced in the double-slit experiment, showing that even electrons have wavelike properties.These experiments shook the foundation of physics by threatening the structure of classical mechanics and destroying humanity’s intuitive framework of reality. But it didn’t stop there. The next step was to tune the beam of electrons down so that the electron gun fired just a single electron at a time. Similar experiments were later used with lasers wherein individual photons were fired seconds apart from each other. The results were mind-bending.Completely against expectation these experiments also produced interference patterns over time as the collection of electrons (or photons) continued to build (Figure 6).Figure 12-6 Over time individual photons construct an interference patternThese observations only added to the confusion. Waves are supposed to be a collective property—something that has no meaning when applied to separate, particulate ingredients. (A water wave, for example, involves a large number of water molecules.) So how can a single electron, or a single photon, be a wave? Furthermore, wave interference requires a wave from one place to interact with a wave from another place. So how can interference be relevantly applied to a single electron or photon? While we are considering such questions, we should also ask, if a single electron or photon is a wave, then what is it that is “waving”? [vii]To answer these questions, Erwin Schrödinger proposed that the stuff that makes up electrons might be smeared out in space and that this smeared electron essence might be what waves. If this idea was correct then we would expect to find all of the electron’s properties, spread out over a distance, but we never do. Every time we locate an electron, we find all of its mass and all of its charge concentrated in one tiny, point-like region. Max Born came up with a different idea. He suggested that the wave is actually a probability wave. [viii] Einstein tinkered with a similar idea when he hypothesized that these waves were optical observations that refer to time averages rather than instantaneous values. Inserting a probability wave (also called a state vector, or a wave function) as a fundamental aspect of Nature delivers another blow to our common-sense ideas about how things truly operate. It suggests that experiments with identical starting conditions do not necessarily lead to identical results because it claims that you can never predict exactly where an electron will be in a single instant. You can only define a probability that we will find it over here, or over there, at any given moment. Two situations with the same probabilistic starting conditions, say of a single particle, might not produce the same results, because the particle can be anywhere within that probability distribution. From a classical perspective, the discovery that the microscopic universe behaves this way is absolutely baffling. Nevertheless, it is how we have observed Nature to be.This leads us to a rather interesting precipice. It seems that the map we have been using to chart physical reality somehow dissolves when we look closely at it. The rules of four-dimensional geometry simply fail to accurately map Nature when we examine the smallest scales. Nature doesn’t strictly behave as our old Euclidean map dictates. Stumbling upon this discovery forces us to face a vital question. Is Nature ultimately and fundamentally probabilistic in a way that we may never understand, as many modern physicists have chosen to believe; or, is this probabilistic quality a byproduct of our reduced dimensional representation of Nature?After pondering these questions long and hard, some physicists have come to believe that the tapestry of spacetime is analogous to water: that the smooth appearance of space and time is only an approximation that must yield to a more fundamental framework when considering ultramicroscopic scales. As far as I can tell, however, up until now this point has only been entertained abstractly. Geometrically resolving a molecular structure for space might resolve our greatest quantum mechanical mysteries, but as of yet, no one has taken that final step. No one has developed a self-consistent picture from this geometric insight. No one has moved beyond the mathematical suggestion that spacetime is analogous to water, or interpreted the theoretical quanta of space as being physically real. Consequently, a framework that enables conceptualization of what is meant by the “molecules” or “atoms” of spacetime has not been developed.Eight decades of meticulous experiments have confirmed the predictions of quantum mechanics based on this wave function, or probability wave, description with amazing precision. “Yet there is still no agreed-upon way to envision what quantum mechanical probability waves actually are. Whether we should say that an electron’s probability wave is the electron, or that it’s associated with the electron, or that it’s a mathematical device for describing the electron’s motion, or that it’s the embodiment of what we can know about the electron is still debated.” [ix]Although quantum mechanics describes the universe as having an inherently probabilistic character, we don’t experience the effects of this character in our day-to-day lives. Why is this? The answer, according to quantum mechanics, is that we don't see quantum events like a chair being here now and then across the room in the next instant, because the probability of that occurring, although not zero, is absurdly miniscule. But what exactly makes the probability for large things to act, as electrons do, so small? At what scales do such effects become important? And, why should the macroscopic universe be so different from the microscopic universe?As if these newly uncovered characteristics of reality weren’t obscure enough, quantum physicists conceptually fuddle things further by suggesting that without observation things have no reality. They claim that until the position of an electron is actually measured the electron has no definite position. Before it is measured, the position exists only as a probability, and then suddenly, through the act of measuring, the electron miraculously acquires the property of position.Einstein acutely recognized the absurdity of this claim. When approached with this conjecture, he famously quipped, “Do you really believe that the moon is not there unless we are looking at it?” [x] To him everything in the physical world had a reality independent of our observations. Measurements that suggested otherwise were mere reflections of the incompleteness by which we currently map and comprehend physical reality. To many quantum physicists, however, the unobserved Moon’s existence became a matter of probability. To them, a discoverable, complete map of physical reality, with the ability to resolve an underlying determinism, became nothing more than a myth—a romantic dream.The mathematical projection of quantum mechanics can be statistically matched with our four-dimensional observations, but when it comes to a conceptual explanation of those observations, it completely lets us down. Intuitive explanations cannot be gleaned from a framework of physical reality that is assumed to be fundamentally probabilistic. By definition, randomness blurs causality. This vague description of physical reality keeps us from grasping a deeper truth by allowing what should be the most basic of concepts to drip into a realm of nonsense.As an example of the confusion that stems from swallowing the standard quantum mechanical interpretation “guts, feathers, and all,” consider the fact that a probabilistic treatment of quantum mechanics leads us to the conclusion that the double-slit experiment can be explained by assuming that a photon actually takes both paths. We can combine the two probability waves emerging from both slits to statistically determine where a photon will land on a screen. The result mimics an interference pattern.According to this, we can explain interference patterns by assuming that one photon somehow always manages to go through both slits, but is this really what is going on? Does a photon really travel along both paths? Can this count as an explanation if we have no coherent sense of what it means? You might notice that if we were to design our experiment with three slits, then we would have to consider whether or not the photon really travels all three routes. This question can be extended for as many slits as you like, but the fundamental conceptual problem remains the same.In order to solve this mystery, you may suggest that we place detectors in front of the slits to determine if the photons are actually going through both slits, or just one. When we do this, we always find that individual photons pass through one slit or the other—never both. But, when we measure the position of individual photons we no longer get an interference pattern and so the question retains its ambiguity. Some have taken this to mean that the act of observation forces wave properties to collapse into a particle, but how and why this theoretical collapse occurs still lacks explanation.Because probability waves are not directly observable and because photons (and electrons) are always found in one place or another when measured, we might be tempted to think that probability waves might not be real—that they were never really there. If that is true, then how are the interference patterns created? Surely these probability waves exist, but in what sense? What are they referencing? Why is it that whenever we know which path the photon takes, we get a classical image instead of an interference pattern? How does the detection of a photon, or an electron, change its behavior?To date, these questions have yet to be resolved. In fact, more clever experiments designed to solve these questions have only deepened the mystery. For example, let’s perform the double-slit experiment again, but this time let’s place devices in front of the slits, which mark (but do not stop or detect) the photons before they pass through the slits. This marking allows us to examine the photons that strike the screen and subsequently determine which slit they passed through. Thus we only gain knowledge of which path the photon takes after the path has been completed. For some reason, however, when we do this we find that the photons do not build up an interference pattern. They form a classical image (Figure 4).Once again, it seems that “which-path” information inhibits us from probing these ghostly waves. But is it really the fact that we gain the ability to determine which path a photon goes through—independent of when we gain that information—that disrupts the interference pattern? Or does our marking of the photon somehow disrupt its interference potential?To explore this question, we perform what’s known as the quantum eraser experiment. We start with the same set up we just described. Then we place another device between each slit and the screen, which completely removes the mark from the photon. We already know that the marked photons project a classical image. Will an interference pattern reemerge if we remove the effects of this mark—if we lose the ability to extract the which-path information?When we perform this experiment the interference pattern does return (Figure 7). Does this mean that photons somehow choose how to act, based on our knowledge of them? Or does it imply something even stranger—that the photons are always both particles and waves simultaneously? How are we to understand either conclusion?Figure 12-7 An interference pattern Another curiosity of Nature is known as the photoelectric effect. Philipp Lenard first discovered this effect through controlled experiments in 1900. When light shines on a metal surface, it causes electrons to be knocked loose and emitted. Knowing this, Lenard designed an experiment that allowed him to control the frequencyof the incoming light. During the experiment, he increased the frequency of the light—moving from infrared heat and red light to violet and ultraviolet. Greater frequencies caused the emitted electrons to speed away with more kinetic energy. After discovering this, Lenard reconfigured his experiment to allow him to control the intensity of the incoming light. He used a carbon arc light that could be made brighter by a factor of 1,000.Because both experiments involved increasing the amount of incoming light energy he expected to have identical results. In other words, because the brighter, more intense light had more energy, Lenard expected that the electrons emitted would have more energy and speed away faster. But that’s not what happened. Instead, the more intense light produced more electrons, but the energy of each electron remained the same. [xi]In response to these experiments Einstein suggested that light is composed of discrete packets called photons. Under this assumption, light with higher frequency would cause electrons to be emitted with more energy, and light with higher intensity, that is, a higher quantity of photons, would result in emission of more electrons—just as we observe.The problem with this solution (a solution that is now universally accepted among physicists) is that it doesn’t provide us with a clear description for what the light quanta are. Why does light come in quantized packets? Near the end of his life Einstein lamented over this problem in a letter to his dear friend Michele Besso. He wrote, “All these fifty years of pondering have not brought me any closer to answering the question, what are light quanta?” [xii] It’s been another fifty years and we seem as confused as ever over how it is that light is quantized into little discrete packets called photons.In the midst of these enigmas lies the uncertainty principle, which states that knowledge of certain properties inhibits knowledge of other complimentary properties. For example, the more accurately we determine the position of an electron, the less we can determine its momentum, and vise versa.Heisenberg tried to explain the uncertainty principle by appealing to the observer effect; claiming that it was simply an observational effect of the fact that measurements of quantum systems cannot be made without affecting those systems. [xiii] Since then, the uncertainty principle has regularly been confused with the observer effect. [xiv] But the uncertainty principle is not a statement about the observational success of current technology. It has nothing to do with the observer effect. It highlights a fundamental property of quantum systems, a property that turns out to be inherent in all wave-like systems. [xv] Uncertainty is an aspect of quantum mechanics because of the wave nature it ascribes to all quantum objects.If our current description of quantum mechanics is fundamental, if there is nothing beneath the state vector—a claim that defines the heart of the standard interpretation of quantum mechanics—then this uncertainty principle may be a sharp enough dagger to kill our quest for an intuitive understanding of physical reality. The corrosive power of the uncertainty principle, when mixed with our current paradigm, is poignantly illustrated by an old story involving Niels Bohr. According to the story, Bohr was once asked what the complementary quality to truth is. After some thought he answered—“clarity.” [xvi] Unlike classical mechanics, which describes systems by specifying the positions and velocities of its components, quantum mechanics uses a complex mathematical object called a state vector (also called the wave function [xvii]) to map physical systems. Interjecting this state vector into the theory enables us to match its predictions to our observations of the microscopic world, but it also generates a relatively indirect description that is open to many equally valid interpretations. This creates a sticky situation, because to “really understand” quantum mechanics we need to be able to specify the exact status of and to have some sort of justification for that specification. At the present, we only have questions. Does the state vector describe physical reality itself, or only some (partial) knowledge that we have of reality? “Does it describe ensembles of systems only (statistical description), or one single system as well (single events)? Assume that indeed, is affected by an imperfect knowledge of the system, is it then not natural to expect that a better description should exist, at least in principle?” [xviii] If so, what would this deeper and more precise description of reality be?To explore the role of the state vector, consider a physical system made of Nparticles with mass, each propagating in ordinary three-dimensional space. In classical mechanics we would use Npositions and N velocities to describe the state of the system. For convenience we might also group together the positions and velocities of those particles into a single vector V, which belongs to a real vector space with 6N dimensions, called phase space. [xix]The state vector can be thought of as the quantum equivalent of this classical vector V. The primary difference is that, as a complex vector, it belongs to something called complex vector space, also known as space of states, or Hilbert space. In other words, instead of being encoded by regular vectors whose positions and velocities are defined in phase space, the state of a quantum system is encoded by complex vectors whose positions and velocities live in a space of states. [xx]The transition from classical physics to quantum physics is the transition from phase space to space of states to describe the system. In the quantum formalism each physical observable of the system (position, momentum, energy, angular momentum, etc.) has an associated linear operator acting in the space of states. (Vectors belonging to the space of states are called “kets.”) The question is, is it possible to understand space of states in a classical manner? Could the evolution of the state vector be understood classically (under a projection of local realism) if, for example, there were additional variables associated with the system that were ignored completely by our current description/understanding of it?While that question hangs in the air, let’s note that if the state vector is fundamental, if there really isn’t a deeper-level description beneath the state vector, then the probabilities postulated by quantum mechanics must also be fundamental. This would be a strange anomaly in physics. Statistical classical mechanics makes constant use of probabilities, but those probabilistic claims relate to statistical ensembles. They come into play when the system under study is known to be one of many similar systems that share common properties, but differ on a level that has not been probed (for any reason). Without knowing the exact state of the system we can group all the similar systems together into an ensemble and assign that ensemble state to our system. This is done as a matter of convenience. Of course, the blurred average state of the ensemble is not as clear as any of the specific states the system might actually have. Beneath that ensemble there is a more complete description of the system’s state (at least in principle), but we don’t need to distinguish the exact state in order to make predictions. Statistical ensembles allow us to make predictions without probing the exact state of the system. But our ignorance of that exact state forces those predictions to be probabilistic.Can the same be said about quantum mechanics? Does quantum theory describe an ensemble of possible states? Or does the state vector provide the most accurate possible description of a single system? [xxi]How we answer that question impacts how we explain unique outcomes. If we treat the state vector as fundamental, then we should expect reality to always present itself in some sort of smeared out sense. If the state vector were the whole story, then our measurements should always record smeared out properties, instead of unique outcomes. But they don’t. We always measure well-defined properties that correspond to specific states. Sticking with the idea that the state vector is fundamental, von Neumann suggested a solution called state vector reduction (also called wave function collapse). [xxii] The idea was that when we aren’t looking, the state of a system is defined as a superposition of all its possible states (characterized by the state vector) and evolves according to the Schrödinger equation. But as soon as we look (or take a measurement) all but one of those possibilities collapse. How does this happen? What mechanism is responsible for selecting one of those states over the rest? To date there is no answer. Despite this, von Neumann’s idea has been taken seriously because his approach allows for unique outcomes.The problem that von Neumann was trying to address is that the Schrödinger equation itself does not select single outcomes. It cannot explain why unique outcomes are observed. According to it, if a fuzzy mix of properties comes in (coded by the state vector), a fuzzy mix of properties comes out. To fix this, von Neumann conjured up the idea that the state vector jumps discontinuously (and randomly) to a single value. [xxiii] He suggested that unique outcomes occur because the state vector retains only the “component corresponding to the observed outcome while all components of the state vector associated with the other results are put to zero, hence the name reduction.” [xxiv]The fact that this reduction process is discontinuous makes it incompatible with general relativity. It is also irreversible, which makes it stand out as the only equation in all of physics that introduces time-asymmetry into the world. If we think that the problem of explaining uniqueness of outcome eclipses these problems, then we might be willing to take them in stride. But to make this trade worthwhile we need to have a good story for how state vector collapse occurs. We don’t. The absence of this explanation is referred to as the quantum measurement problem.Many people are surprised to discover that the quantum measurement problem still stands. It has become popular to explain state vector reduction (wave function collapse) by appealing to the observer effect, asserting that measurements of quantum systems cannot be made without affecting those systems, and that state vector reduction is somehow initiated by those measurements. [xxv] This may sound plausible, but it doesn’t work. Even if we ignore the fact that this ‘explanation’ doesn’t elucidate howa disturbance could initiate state vector reduction, this isn’t an allowed answer because “state vector reduction can take place even when the interactions play no role in the process.” [xxvi] This is illustrated by negative measurements or interaction free measurements in quantum mechanics.To explore this point, consider a source, S, that emits a particle with a spherical wave function, which means its values are independent of the direction in space. [xxvii] In other words, it emits photons in random directions, each direction having equal probability. Let’s surround the source by two detectors with perfect efficiency. The first detector D1should be set up to capture the particle emitted in almost all directions, except a small solid angle θ, and the second detector D2 should be set up to capture the particle if it goes through this solid angle (Figure 8).Figure 8 An interaction-free measurement When the wave packet describing the wave function of the particle signNowes the first detector, it may or may not be detected. (The probability of detection depends on the ratio of the subtended angles of the detectors.) If the particle is detected by D1 it disappears, which means that its state vector is projected onto a state containing no particle and an excited detector. In this case, the second detector D2will never record a particle. If the particle isn’t detected by D1 then D2 will detect the particle later. Therefore, the fact that the first detector has not recorded the particle implies a reduction of the wave function to its component contained within θ, implying that the second detector will always detect the particle later. In other words, the probability of detection by D2 has been greatly enhanced by a sort of “non-event” at D1. In short, the wave function has been reduced without any interaction between the particle and the first measurement apparatus.Franck Laloë notes that this illustrates that “the essence of quantum measurement is something much more subtle than the often invoked ‘unavoidable perturbations of the measurement apparatus’ (Heisenberg microscope, etc.).” [xxviii] If state vector reduction really takes place, then it takes place even when the interactions play no role in the process, which means that we are completely in the dark about how this reduction is initiated or how it unfolds. Why then is state vector reduction still taken seriously? Why would any thinking physicist uphold the claim that state vector reduction occurs, when there is no plausible story for how or why it occurs, and when the assertion that it does occur creates other monstrous problems that contradict central tenets of physics? The answer may be that generations of tradition have largely erased the fact that there is another way to solve the quantum measurement problem.Returning to the other option at hand, we note that if we assume that the state vector is a statistical ensemble, if we assume that the system does have a more exact state, then the interpretation of this thought experiment becomes straightforward; initially the particle has a well-defined direction of emission, and D2records only the fraction of the particles that were emitted in its direction.Standard quantum mechanics postulates that this well-defined direction of emission does not exist before any measurement. Assuming that there is something beneath the state vector, that a more accurate state exists, is tantamount to introducing additional variables to quantum mechanics. It takes a departure from tradition, but as T. S. Eliot said in The Sacred Wood, “tradition should be positively discouraged.” [xxix] The scientific heart must search for the best possible answer. It cannot flourish if it is constantly held back by tradition, nor can it allow itself to ignore valid options. Intellectual journeys are obliged to forge new paths.So instead of asking whether of not wave-particle duality is an illusion, perhaps we should ask whether wave-particle duality implies that the state vector is the most fundamental description of a quantum mechanical system, or if a deeper level description exists? That's an open question, and at the moment there are many possible answers — interpretations of quantum mechanics that are equally aligned with the empirical evidence. What's your answer?For more on this topic, and to discover how pilot-wave theory is elucidated by the assumption that the vacuum is a superfluid, see Einstein's Intuition, available in black and white softcover, full color softcover, full color hardcover, an iBook, and as an audiobook.[i] The discussion on interference and the double-slit experiment that follows is further developed by Brian Greene, (2004). The Fabric of the Cosmos: Space, Time and the Texture of Reality. New York: Knopf, pp. 84–84. Greene’s discussion was used as a general guide here.[ii] In order to show diffraction (a fuzzy border of light on the projected image) the slit must have a width that does not greatly exceed the wavelength of the color of the light that we have chosen.[iii] Light’s wave nature was first revealed in the mid-seventeenth century through experiments performed by the Italian scientist Francesco Maria Grimaldi, and was later expanded upon by experiments performed in 1803 by the physician and physicist Thomas Young. (1807). Interference of Light; Alan Lightman. A Sense Of The Mysterious. pp. 51–52, 71.[iv] Before the “planetary model” of the atom, physicists pictured the atom being a plum-shaped blob (the nucleus) with tiny protruding springs that each had an electron stuck to its end. When the atom absorbed energy it was thought that these electrons would jiggle (oscillate) on the ends of their springs. Consequently, any atom that was above its ground state of energy was understood to be an “excited atomic oscillator,” This depiction of the atom wasn’t overthrown until 1900. At that point in history the physical existence of atoms was still controversial. It was replaced by the planetary model, which in turn was replaced by the electron cloud model we use today—a model that was initiated in 1910 and was secured by 1930. Gary Zukav. The Dancing Wu Li Masters, pp. 49–50.[v] Electrons can be individually counted and you can individually place them on a drop of oil and measure their electric charge. Richard Feynman. (1988). QED, The Strange Theory of Light and Matter. Princeton University Press, p. 84.[vi] According to de Broglie’s doctoral thesis all matter has corresponding waves. The wavelength of the “matter waves” that “correspond” to matter depends upon the momentum of the particle. Specifically, , which falls into an important group of equations along with Planck’s equation ) and the ever famous . (λ, pronounced “lambda,” stands for wavelength, h is Planck’s constant, and pronounced ‘nu’ represents the frequency of a photon) From this equation we are told to expect that when we send a beam of electrons (something we might traditionally think of as a stream of particles) through tiny openings, like the spacing between atoms in a piece of nickel crystal, the beam will diffract, just like light diffracts. The only requirement here is that the spacing between the atoms of the material must be as small, or smaller, than the electron’s corresponding wavelength—just like the slits in our double-slit experiment. When we perform the experiment, diffraction and therefore interference, occurs exactly as wave mechanics predicts.[vii] Part of the problem here is that in keeping with our four-dimensional intuition we tend to assume a particle aspect in the double-slit experiment without accounting for nonlocality. By doing this we are technically violating Heisenberg’s uncertainty principle and missing the bigger picture.[viii] M. Born. (1926). Quantenmechanik der Stossvorgänge. Zeitschrift für Physik 38, 803–827; (1926). Zur Wellenmechanik der Stossvorgänge. Göttingen Nachrichten 146–160.[ix] Brian Greene. (2004), p. 91.[x] Albert Einstein quoted in Einstein by Walter Isaacson.[xi] Walter Isaacson. Einstein, pp. 96–97.[xii] Ibid.[xiii] Werner Heisenberg. The Physical Principles of the Quantum Theory, p. 20.[xiv] Masano Ozawa. (2003). Universally valid reformulation of the Heisenberg uncertainty principle on noise and disturbance in measurement. Physical Review A 67 (4), arXiv:quant-ph/0207121; Aya Furuta. (2012). One Thing Is Certain: Heisenberg’s Uncertainty Principle Is Not Dead. Scientific American.[xv] L. A. Rozema, A. Darabi, D. H. Mahler, A. Hayat, Y, Soudagar, & A. M. Steinberg. (2012). Violation of Heisenberg’s Measurement—Disturbance Relationship by Weak Measurements. Physical Review Letters 109 (10).[xvi] Steven Weinberg. Dreams Of A Final Theory, p. 74.[xvii] For a system of spinless particles with masses, the state vector is equivalent to a wave function, but for more complicated systems this is not the case. Nevertheless, conceptually they play the same role and are used in the same way in the theory, so that we do not need to make a distinction here. Franck Laloë. Do We Really Understand Quantum Mechanics?, p. 7.[xviii] Franck Laloë. Do We Really Understand Quantum Mechanics?, p. xxi.[xix] There are 6N dimensions in this phase space because there are N particles in the system and each particle comes with 6 data points (3 for its spatial position (x, y, z) and 3 for its velocity, which has x, y, zcomponents also).[xx] The space of states (complex vector space or Hilbert space) is linear, and therefore, conforms to the superposition principle. Any combination of two arbitrary state vectors and within the space of states is also a possible state for the system. Mathematically we write where & are arbitrary complex numbers.[xxi] Franck Laloë. Do We Really Understand Quantum Mechanics?, p. 19.[xxii] Chapter VI of J. von Neumann. (1932). Mathematische Grundlagen der Quantenmechanik, Springer, Berlin; (1955). Mathematical Foundations of Quantum Mechanics, Princeton University Press.[xxiii] It might be useful to challenge the logical validity of the claim that something can “cause a random occurrence.” By definition, causal relationships drive results, while “random” implies that there is no causal relationship. Deeper than this, I challenge the coherence of the idea that genuine random occurrences can happen. We cannot coherently claim that there are occurrences that are completely void of any causal relationship. To do so is to wisk away what we mean by “occurrences.” Every occurrence is intimately connected to the whole, and ignorance of what is driving a system is no reason to assume that it is randomly driven. Things cannot be randomly driven. Cause cannot be random.[xxiv] Franck Laloë. Do We Really Understand Quantum Mechanics?, p. 11.[xxv] Bohr preferred another point of view where state vector reduction is not used. D. Howard. (2004). Who invented the Copenhagen interpretation? A study in mythology. Philos. Sci. 71, 669–682.[xxvi] Franck Laloë. Do We Really Understand Quantum Mechanics?, p. 28.[xxvii] This example was inspired by section 2.4 of Franck Laloë’s book, Do We Really Understand Quantum Mechanics?, p. 27–31.[xxviii] Franck Laloë. Do We Really Understand Quantum Mechanics?, p. 28.[xxix] T. S. Eliot. (1921). The Sacred Wood. Tradition and the Individual Talent.
-
What are the important sections of cyber laws in India?
The Government of India enacted its Information Technology Act 2000 with the objectives stating officially as: “to provide legal recognition for transactions carried out by means of electronic data interchange and other means of electronic communication, commonly referred to as "electronic commerce", which involve the use of alternatives to paper-based methods of communication and storage of information, to facilitate electronic filing of documents with the Government agencies and further to amend the Indian Penal Code, the Indian Evidence Act, 1872, the Bankers' Books Evidence Act, 1891 and the Reserve Bank of India Act, 1934 and for matters connected therewith or incidental thereto.The Act essentially deals with the following issues: Legal Recognition of Electronic Documents Legal Recognition of Digital Signatures Offenses and Contraventions Justice Dispensation Systems for cyber crimes.CYBER CRIME- Cyber Crime is not defined officially in IT Act or in any other legislation. In fact, it cannot be too. Offence or crime has been dealt with elaborately listing various acts and the punishments for each, under the Indian Penal Code, 1860 and related legislations. Hence, the concept of cyber crime, is just a "combination of crime and computer". Cybercrime means any illegal behavior directed by means of electronic operations that targets the security of computer systems and the data processed by them. Furthermore any illegal behavior committed by means of, or in relation to, a computer system or network, including such crimes as illegal possession and offering or distributing information by means of a computer system or network. Any contract for the sale or conveyance of immovable property or any interest in such property; Any such class of documents or transactions as may be notified by the Central Here are some of the sections of the IT Act 2000 which are related to cyber crimes: Section 43 - Penalty and Compensation for damage to computer, computer system, If any person without permission of the owner or any other person who is in-charge of a computer, computer system or computer network – (a) accesses or secures access to such computer, computer system or computer network or computer resource (b) downloads, copies or extracts any data, computer data, computer database or information from such computer, computer system or computer network including information or data held or stored in any removable storage medium; (c) introduces or causes to be introduced any computer contaminant or computer virus into any computer, computer system or computer network- (d) damages or causes to be damaged any computer, computer system or computer network, data, computer database, or any other programmes residing in such computer, computer system or computer network-3. (e) disrupts or causes disruption of any computer, computer system, or computer network; (f) denies or causes the denial of access to any person authorised to access any computer, computer system or computer network by any means (h) charges the services availed of by a person to the account of another person by tampering with or manipulating any computer of a computer, computer system or computer network- (g) provides any assistance to any person to facilitate access to a computer, computer system or computer network in contravention of the provisions of this Act, rules or regulations made there under, (h) charges the services availed of by a person to the account of another person by tampering with or manipulating any computer, computer system, or computer network, (i) destroys, deletes or alters any information residing in a computer resource or diminishes its value or utility or affects it injuriously by any means, (j) Steals, conceals, destroys or alters or causes any person to steal, conceal, destroy or alter any computer source code used for a computer resource with an intention to cause damage, he shall be liable to pay damages by way of compensation to the person so affected. Section 43A - Compensation for failure to protect data Where a body corporate, possessing, dealing or handling any sensitive personal data or information in a computer resource which it owns, controls or operates, is negligent in implementing and maintaining reasonable security practices and procedures and thereby causes wrongful loss or wrongful gain to any person, such body corporate shall be liable to pay damages by way of compensation, not exceeding five crore rupees, to the person so affected. Section 65 - Tampering with Computer Source Documents If any person knowingly or intentionally conceals, destroys code or alters or causes another to conceal, destroy code or alter any computer, computer programme, computer system, or computer network, he shall be punishable with imprisonment up to three years, or with fine up to two lakh rupees, or with both. Section 66 - Computer Related Offences If any person, dishonestly, or fraudulently, does any act referred to in section 43, he shall be punishable with imprisonment for a term which may extend to two three years or with fine which may extend to five lakh rupees or with both. Section 66A - Punishment for sending offensive messages through communication service Any person who sends, by means of a computer resource or a communication device, (a) any information that is grossly offensive or has menacing character; (b) any information which he knows to be false, but for the purpose of causing annoyance, inconvenience, danger, obstruction, insult, injury, criminal intimidation, enmity, hatred, or ill will, persistently makes by making use of such computer resource or a communication device, (c) any electronic mail or electronic mail message for the purpose of causing annoyance or inconvenience or to deceive or to mislead the addressee or recipient about the origin of such messages shall be punishable with imprisonment for a term which may extend to three years and with fine. Section 66B - Punishment for dishonestly receiving stolen computer resource or communication device. Whoever dishonestly receives or retains any stolen computer resource or communication device knowing or having reason to believe the same to be stolen computer resource or communication device,4. shall be punished with imprisonment of either description for a term which may extend to three years or with fine which may extend to rupees one lakh or with both. Section 66C - Punishment for identity theft Whoever, fraudulently or dishonestly make use of the electronic signature, password or any other unique identification feature of any other person, shall be punished with imprisonment of either description for a term which may extend to three years and shall also be liable to fine which may extend to rupees one lakh. Section 66D - Punishment for cheating by personation by using computer resource Whoever, by means of any communication device or computer resource cheats by personating; shall be punished with imprisonment of either description for a term which may extend to three years and shall also be liable to fine which may extend to one lakh rupees. Section 66E - Punishment for violation of privacy Whoever, intentionally or knowingly captures, publishes or transmits the image of a private area of any person without his or her consent, under circumstances violating the privacy of that person, Explanation - For the purposes of this section: (a) “transmit” means to electronically send a visual image with the intent that it be viewed by a person or persons; (b) “capture”, with respect to an image, means to videotape, photograph, film or record by any means; (c) “private area” means the naked or undergarment clad genitals, pubic area, buttocks or female breast; (d) “publishes” means reproduction in the printed or electronic form and making it available for public; (e) “under circumstances violating privacy” means circumstances in which a person can have a reasonable expectation that-- (i) he or she could disrobe in privacy, without being concerned that an image of his private area was being captured; or (ii) any part of his or her private area would not be visible to the public, regardless of whether that person is in a public or private place. shall be punished with imprisonment which may extend to three years or with fine not exceeding two lakh rupees, or with both. Section-66F Cyber Terrorism Whoever,- with intent to threaten the unity, integrity, security or sovereignty of India or to strike terror in the people or any section of the people by – (i) denying or cause the denial of access to any person authorized to access computer resource; or (ii) attempting to penetrate or access a computer resource without authorisation or exceeding authorized access; or (iii) introducing or causing to introduce any Computer Contaminant and by means of such conduct causes or is likely to cause death or injuries to persons or damage to or destruction of property or disrupts or knowing that it is likely to cause damage or disruption of supplies or services essential to the life of the community or adversely affect the critical information infrastructure specified under section 70, Whoever commits or conspires to commit cyber terrorism shall be punishable with imprisonment which may extend to imprisonment for life. Section 67 - Punishment for publishing or transmitting obscene material in electronic form Whoever publishes or transmits or causes to be published in the electronic form, any material which is lascivious or appeals to the prurient interest or if its effect is such as to tend to deprave and corrupt persons who are likely, having regard to all relevant circumstances, to read, see or hear the matter contained or embodied in it, shall be punished on first conviction with imprisonment of either description for a term which5. may extend to two three years and with fine which may extend to five lakh rupees and in the event of a second or subsequent conviction with imprisonment of either description for a term which may extend to five years and also with fine which may extend to ten lakh rupees. Section 67A - Punishment for publishing or transmitting of material containing sexually explicit act, etc. in electronic form Whoever publishes or transmits or causes to be published or transmitted in the electronic form any material which contains sexually explicit act or conduct shall be punished on first conviction with imprisonment of either description for a term which may extend to five years and with fine which may extend to ten lakh rupees and in the event of second or subsequent conviction with imprisonment of either description for a term which may extend to seven years and also with fine which may extend to ten lakh rupees. Section 67B - Punishment for publishing or transmitting of material depicting children in sexually explicit act, etc. in electronic form Whoever:- (a) publishes or transmits or causes to be published or transmitted material in any electronic form which depicts children engaged in sexually explicit act or conduct or (b) creates text or digital images, collects, seeks, browses, downloads, advertises, promotes, exchanges or distributes material in any electronic form depicting children in obscene or indecent or sexually explicit manner or (c) cultivates, entices or induces children to online relationship with one or more children for and on sexually explicit act or in a manner that may offend a reasonable adult on the computer resource or (d) facilitates abusing children online or (e) records in any electronic form own abuse or that of others pertaining to sexually explicit act with children, shall be punished on first conviction with imprisonment of either description for a term which may extend to five years and with a fine which may extend to ten lakh rupees and in the event of second or subsequent conviction with imprisonment of either description for a term which may extend to seven years and also with fine which may extend to ten lakh rupees: Section 69 - Powers to issue directions for interception or monitoring or decryption of any information through any computer resource.- (1) Where the central Government or a State Government or any of its officer specially authorized by the Central Government or the State Government, as the case may be, in this behalf may, if is satisfied that it is necessary or expedient to do in the interest of the sovereignty or integrity of India, defence of India, security of the State, friendly relations with foreign States or public order or for preventing incitement to the commission of any cognizable offence relating to above or for investigation of any offence, it may, subject to the provisions of sub-section (2), for reasons to be recorded in writing, by order, direct any agency of the appropriate Government to intercept, monitor or decrypt or cause to be intercepted or monitored or decrypted any information transmitted received or stored through any computer resource. (2) The Procedure and safeguards subject to which such interception or monitoring or decryption may be carried out, shall be such as may be prescribed. (3) The subscriber or intermediary or any person in charge of the computer resource shall, when called upon by any agency which has been directed under sub section (1), extend all facilities and technical assistance to -6. (a) provide access to or secure access to the computer resource generating, transmitting, receiving or storing such information; or (b) intercept or monitor or decrypt the information, as the case may be; or (c) provide information stored in computer resource. (4) The subscriber or intermediary or any person who fails to assist the agency referred to in sub-section (3) shall be punished with an imprisonment for a term which may extend to seven years and shall also be liable to fine. Section 69A - Power to issue directions for blocking for public access of any information through any computer resource (1) Where the Central Government or any of its officer specially authorized by it in this behalf is satisfied that it is necessary or expedient so to do in the interest of sovereignty and integrity of India, defense of India, security of the State, friendly relations with foreign states or public order or for preventing incitement to the commission of any cognizable offence relating to above, it may subject to the provisions of sub-sections (2) for reasons to be recorded in writing, by order direct any agency of the Government or intermediary to block access by the public or cause to be blocked for access by public any information generated, transmitted, received, stored or hosted in any computer resource. (2) The procedure and safeguards subject to which such blocking for access by the public may be carried out shall be such as may be prescribed. (3) The intermediary who fails to comply with the direction issued under sub-section (1) shall be punished with an imprisonment for a term which may extend to seven years and also be liable to fine. Section 69B. Power to authorize to monitor and collect traffic data or information through any computer resource for Cyber Security (1) The Central Government may, to enhance Cyber Security and for identification, analysis and prevention of any intrusion or spread of computer contaminant in the country, by notification in the official Gazette, authorize any agency of the Government to monitor and collect traffic data or information generated, transmitted, received or stored in any computer resource. (2) The Intermediary or any person in-charge of the Computer resource shall when called upon by the agency which has been authorized under sub-section (1), provide technical assistance and extend all facilities to such agency to enable online access or to secure and provide online access to the computer resource generating, transmitting, receiving or storing such traffic data or information. (3) The procedure and safeguards for monitoring and collecting traffic data or information, shall be such as may be prescribed. (4) Any intermediary who intentionally or knowingly contravenes the provisions of subsection (2) shall be punished with an imprisonment for a term which may extend to three years and shall also be liable to fine. Section 71. Penalty for misrepresentation Whoever makes any misrepresentation to, or suppresses any material fact from, the Controller or the signNowing Authority for obtaining any license or Electronic Signature Certificate, as the case may be, shall be punished with imprisonment for a term which may extend to two years, or with fine which may extend to one lakh rupees, or with both.7. Section 72 - BsignNow of confidentiality and privacy Any person who, in pursuant of any of the powers conferred under this Act, rules or regulations made there under, has secured access to any electronic record, book, register, correspondence, information, document or other material without the consent of the person concerned discloses such electronic record, book, register, correspondence, information, document or other material to any other person shall be punished with imprisonment for a term which may extend to two years, or with fine which may extend to one lakh rupees, or with both. These are the IPC Section codes : Section 499. Defamation Whoever, by words either spoken or intended to be read, or by signs or by visible representations, makes or publishes any imputation concerning any person intending to harm, or knowing or having reason to believe that such imputation will harm, the reputation of such person, is said, except in the cases hereinafter expected, to defame that person. It may amount to defamation to impute anything to a deceased person, if the imputation would harm the reputation of that person if living, and is intended to be hurtful to the feelings of his family or other near relatives. First Exception.—Imputation of truth which public good requires to be made or published Second Exception.—Public conduct of public servants Third Exception.—Conduct of any person touching any public question Fourth Exception.—Publication of reports of proceedings of Courts Fifth Exception.-Merits of case decided in Court or conduct of witnesses and others concerned. Sixth Exception.—Merits of public performance Seventh Exception.—Censure passed in good faith by person having lawful authority over another. Eighth Exception.—Accusation preferred in good faith to authorised person. Ninth Exception.—Imputation made in good faith by person for protection of his or other’s interests Tenth Exception.—Caution intended for good of person to whom conveyed or for public good Section 500. Punishment for defamation Whoever defames another shall be punished with simple imprisonment for a term which may extend to two years, or with fine, or with both.8. CLASSIFICATION OF OFFENCE Para I Punishment—Simple imprisonment for 2 years, or fine, or both—Non-cognizable—Bailable—Triable by Court of Session—Compoundable by the person defamed. Para II Punishment—Simple imprisonment for 2 years, or fine, or both—Non-cognizable—Bailable—Triable by Magistrate of the first class—Compoundable by the person defamed with the permission of the court Section 420 Cheating and dishonestly inducing delivery of property Whoever cheats and thereby dishonestly induces the person deceived to deliver any property to any person, or to make, alter or destroy the whole or any part of a valuable security, or anything which is signed or sealed, and which is capable of being converted into a valuable security, shall be punished with imprisonment of either description for a term which may extend to seven years, and shall also be liable to fine.CLASSIFICATION OF OFFENCE Punishment—Imprisonment for 7 years and fine—Cognizable—Non-bailable—Triable by Magistrate of the first class—Compoundable by the person cheated with the permission of the court. Section 383. Extortion Whoever intentionally puts any person in fear of any injury to that person, or to any other, and thereby dishonestly induces the person so put in fear to deliver to any property or valuable security, or anything signed or sealed which may be converted into a valuable security, commits “extortion”. Example; (a) A threatens to publish a defamatory libel concerning Z unless Z give him money. He thus induces Z to give him money. A has committed extortion. (b) A threatens Z that he will keep Z’s child in wrongful confinement, unless Z will sign and deliver to A promissory note binding Z to pay certain monies to A. Z signs and delivers the note. A has committed extortion. (c) A threatens to send club-men to plough up Z’s field unless Z will sign and deliver to B bond binding Z under a penalty to deliver certain produce to B, and thereby induces Z to sing and deliver the bond. A has committed extortion. (d) A, by putting Z in fear of grievous hurt, dishonestly induces Z to sign or affix his seal to a blank paper and deliver it to A. Z signs and delivers the paper to A. Here, as the paper so signed may be converted into a valuable security. A has committed extortion. Section 384. Punishment for extortion Whoever commits extortion shall be punished with imprisonment of either description for a term which may extend to three years, or with fine or with both.9. CLASSIFICATION OF OFFENCE Punishment—Imprisonment for 3 years, or fine, or both—Cognizable—Non-bailable—Triable by any Magistrate—Non-compoundable.Section 463. Forgery Whoever makes any false documents or false electronic record or part of a document or electronic record, with intent to cause damage or injury], to the public or to any person, or to support any claim or title, or to cause any person to part with property, or to enter into any express or implied contract, or with intent to commit fraud or that fraud may be committed, commits forgery.Section 465. Punishment for forgery Whoever commits forgery shall be punished with imprisonment of either description for a term which may extend to two years, or with fine, or with both.CLASSIFICATION OF OFFENCE Punishment—Punishment for forgery of such document—Cognizable—Bailable—Triable by Magistrate of the first class—Non-compoundable. Section 503. Criminal intimidation Whoever threatens another with any injury to his person, reputation or property, or to the person or reputation of any one in whom that person is interested, with intent to cause alarm to that person, or to cause that person to do any act which he is not legally bound to do, or to omit to do any act which that person is legally entitled to do, as the means of avoiding the execution of such threat, commits criminal intimidation. Explanation A threat to injure the reputation of any deceased person in whom the person threatened is interested, is within this section. Illustration A, for the purpose of inducing B to desist from prosecuting a civil suit, threatens to burn B’s house. A is guilty of criminal intimidation. The following are the live cases : Section 43 Related Case: Mphasis BPO Fraud: 2005 In December 2004, four call centre employees, working at an outsourcing facility operated by MphasiS in India, obtained PIN codes from four customers of MphasiS’ client, Citi Group. These employees were not authorized to obtain the PINs. In association with others, the call centre employees opened new accounts at Indian banks using false identities. Within two months, they used the PINs and account information gleaned during their employment at MphasiS to transfer money from the bank accounts of CitiGroup customers to the new accounts at Indian banks.10. By April 2005, the Indian police had tipped off to the scam by a U.S. bank, and quickly identified the individuals involved in the scam. Arrests were made when those individuals attempted to withdraw cash from the falsified accounts, $426,000 was stolen; the amount recovered was $230,000. Verdict: Court held that Section 43(a) was applicable here due to the nature of unauthorized access involved to commit transactions. Section 65 Related Case: Syed Asifuddin and Ors. Vs. The State of Andhra Pradesh In this case, Tata Indicom employees were arrested for manipulation of the electronic 32- bit number (ESN) programmed into cell phones theft were exclusively franchised to Reliance Infocomm. Verdict: Court held that tampering with source code invokes Section 65 of the Information Technology Act.Section 66 Related Case: Kumar v/s Whiteley In this case the accused gained unauthorized access to the Joint Academic Network (JANET) and deleted, added files and changed the passwords to deny access to the authorized users. Investigations had revealed that Kumar was logging on to the BSNL broadband Internet connection as if he was the authorized genuine user and ‘made alteration in the computer database pertaining to broadband Internet user accounts’ of the subscribers. The CBI had registered a cyber crime case against Kumar and carried out investigations on the basis of a complaint by the Press Information Bureau, Chennai, which detected the unauthorised use of broadband Internet. The complaint also stated that the subscribers had incurred a loss of Rs 38,248 due to Kumar’s wrongful act. He used to ‘hack’ sites from Bangalore, Chennai and other cities too, they said. Verdict: The Additional Chief Metropolitan Magistrate, Egmore, Chennai, sentenced N G Arun Kumar, the techie from Bangalore to undergo a rigorous imprisonment for one year with a fine of Rs 5,000 under section 420 IPC (cheating) and Section 66 of IT Act (Computer related Offence). section 66 A Relevant Case #1: Fake profile of President posted by imposter On September 9, 2010, the imposter made a fake profile in the name of the Hon’ble President Pratibha Devi Patil. A complaint was made from Additional Controller, President Household, President Secretariat regarding the four fake profiles created in the name of Hon’ble President on social networking website, Facebook. The said complaint stated that president house has nothing to do with the facebook and the fake profile is misleading the general public. The First Information Report Under Sections 469 IPC and 66A Information Technology Act, 2000 was registered based on the said complaint at the police station, Economic Offences Wing, the elite wing of Delhi Police which specializes in investigating economic crimes including cyber offences. Relevant Case #2: Bomb Hoax mail In 2009, a 15-year-old Bangalore teenager was arrested by the cyber crime investigation cell (CCIC) of the city crime branch for allegedly sending a hoax e-mail to a private news channel. In the e-mail, he claimed to have planted five bombs in Mumbai, challenging the police to find them before it was too late. At around 1p.m. on May 25, the news channel received an e-mail that read: “I have planted five bombs in Mumbai; you have two hours to find it.” The police, who were alerted immediately, traced the Internet Protocol (IP) address to Vijay Nagar in Bangalore. The Internet service provider for the account was BSNL, said officials. section 66 C Relevant Cases: security number was exposed by Matt Lauer on NBC’s Today Show. Davis’ identity was used to obtain a $500 cash advance loan. University of Pennsylvania faked his own death, complete with a forged obituary in his local paper. Nine months later, Li attempted to obtain a new driver’s license with the intention of applying for new credit cards eventually.Section 66C: Punishment for identity theft Imprisonment upto three years and Fine upto Rs. 1 Lakhs.Section 66D: Punishment for cheating by personation by using computer resourceSection 66E: Punishment for violation of privacy Imprisonment upto three years and/or Fine upto Rs. 2 LakhsSection 66F: Punishment for cyber terrorism May extend to Life imprisonment -do- Non bailable.Section 67: Publishing obscene information in electronic form FirstConviction: Imprisonment upto three years and Fine upto Rs. 5 LakhsSecond or subsequent Conviction : Imprisonment upto five years and Fine upto Rs. 10 Lakhs -do- Bailable in case of first conviction only. Second or subsequent conviction shall be non bailableSection 67A: Punishment for publishing or transmitting of material containing sexually explicit act, etc. in electronic form First Conviction:Imprisonment upto Five years and Fine upto Rs. 10 LakhsSecond or subsequent Conviction : Imprisonment upto Seven years and Fine upto Rs. 10 Lakhs -do- Non-bailable in both first and second conviction.Section 67B: Punishment for publishing or transmitting of material depicting children in sexually explicit act, etc. in electronic form.Section 67C (2): Deliberate Failure by the intermediary to preserve and retain information as specified by the Central Government.Section 68 (2): Deliberate Failure to comply with the order/direction of controller.Section 69 (4): Failure to extend facilities to decrypt information to govt. notified agencySection 69A (3): Punishment for failure by the intermediary to comply with the order of the notified agency to block websites etc.Section 69B (4): Deliberate failure by the intermediary to provide the notified agency with the technical assistance or online access to the computer resource.Section 70: Unauthorized access to protected system directly or indirectly affects the facility of Critical Information Infrastructure.Section 72A: Punishment for Disclosure of information in bsignNow of lawful contract Indian Arms Act 1959 Imprisonment upto three years and Fine .Bailable Imprisonment for a term not exceeding two years or to a fine not exceeding one lakh rupees or to both Imprisonment for a term which may extend to seven years and fine Imprisonment for a term which may extend to three years and fine Imprisonment up to 10 years and fine Cognizable Non bailable Imprisonment for a term upto three years or to a fine upto Rs. 5 Lakhs or to both.Chapter V – Offences and Penalties Sec.25 – Punishment for certain offencesSec.26 – Secret contraventionsSec.27 – Punishment for using arms, etc. Non cognizable -do- Cognizable Non bailable Non Cognizable BailableSec.28 – Punishment for use and possession of firearms or imitation firearms in certain casesSec.29 – Punishment for knowingly purchasing arms, etc., from unlicensed person or for delivering arms, etc., to person not entitled to possess the sameSec.30 – Punishment for contravention of licence or ruleSec.31 – Punishment for subsequent offencesSec.32 – Power to confiscateSec.33 – Offence by companies NDPS ACT On 8th September, 2011, the Government introduced the NDPS (Amendment) Bill, 2011 in the Lok Sabha. The Bill was referred to the Parliamentary Standing Committee on Finance on 13th September, 2011 for further consideration. The Narcotic Drugs and Psychotropic Substances (NDPS) Act, 1985 is the central law on control, regulation and prohibition of narcotic and psychotropic drugs in India. The Act was last amended in 2001, to rationalize punishment and adopt a sentencing structure based on the quantity of drugs involved. The stringent penal structure and rigid implementation of the NDPS Act created many problems including non-availability of opioid medication and lack of access to drug dependence treatment. The Bill seeks to amend a number of provisions of the NDPS Act including:•Modification of the definitions of ‘small’ and ‘commercial’ quantity to include the entire amount of drugs involved and not only the pure drug content [Section 2(xxiiia) and Section 2(viia)]•Standardisation of punishment for consumption of drugs to a maximum of 6 months or fine [Section 27]•Transfer of power to regulate “poppy straw concentrate” from the State to the Central Government [Sections 9 and 10]•Widening provisions for forfeiture of illegally acquired property, wherein any property of a person who is alleged to be involved in illicit traffic whose source cannot be proved is termed as ‘illegally acquired property’ and liable to be seized [Sections 68-B, 68H and 68-O]•Addition of the term ‘management’ to provisions on treatment for drug dependence [Section 71] Concerns over the Bill The proposed quantity definitions would have far signNowing implications on sentencing for NDPS offences and may expose low-level drug offenders, including people who use drugs to stringent punishment. Despite standardisation of punishment for consumption of drugs, the policy of criminalisation of drug use remains unchanged. The overbroad scope of the forfeiture provision makes it susceptible to misuse and subject to constitutional challenges. Further still, the Bill fails to address key issues and contradictions that have arisen such as, death penalty for repeat offenders, immunity for treatment seeking, regulation of treatment centres, support for harm reduction measures and access to opioid medicines. Read more. The Lawyers Collective expressed these and other concerns to the Standing Committee on Finance through written and oral submissions on the NDPS (Amendment) Bill, 2011 My request to all the people is to be safe and to be alert and not involve in wrong activities.
-
What is a good annotation of the Bitcoin white paper?
[BAD EARLY DRAFT - This is being continually revised and updated, with important edits from - I hope - you. If I use your suggestion, I will credit you (unless you prefer otherwise). I especially welcome help from developers, cyrptographers, cypherpunks and other writers. I have not coded since high school.]With your help, the best annotation of the Bitcoin white paper will be below - co-built by you, me and other Quorans working together.Our annotation will be the most informative, most plain English and most entertaining annotation of the Bitcoin white paper.Here we go.Bitcoin: A Peer-to-Peer Electronic Cash SystemPeer-to-peer means you and me and indirectly hints at no centralized entity.Electronic cash system means a way to move money (cash) over the internet. Think PayPal instead of paper dollar bills.Bitcoin is 9 years old and is barely used as electronic cash right now.People HODL (stick their Bitcoin under a virtual mattress), use Bitcoin as a capital flight conduit (from e.g. Venezuelan Bolivar to BTC to USD, Swiss Francs, gold, etc.)As inception, Bitcoin was not intended to be digital gold but maybe it’s destined to be that.This is changing as big exchanges like Coinbase (investor) add SegWit and Lightning.Satoshi Nakamoto satoshin@gmx.com http://www.bitcoin.orgSatoshi Nakamoto is a pseudonym. We still don’t know who wrote the paper. Though the NSA might. How the NSA identified Satoshi Nakamoto – CryptoMuse – MediumAbstract. A purely peer-to-peer version of electronic cash would allow online payments to be sent directly from one party to another without going through a financial institution.The phrases “purely peer-to-peer”, “sent directly” and “without going through a financial institution” strongly suggests the author’s anti-centralization DNA.Digital signatures provide part of the solution, but the main benefits are lost if a trusted third party is still required to prevent double-spending.Now we get at one of the foundational things the paper and the Bitcoin code solves. Bitcoin is a digital asset that I can give you, but if I do that, I can’t give it to someone else because the Bitcoin blockchain code does not permit it.We propose a solution to the double-spending problem using a peer-to-peer network.Bitcoin removes central points of failure.The network timestamps transactions by hashing them into an ongoing chain of hash-based proof-of-work, forming a record that cannot be changed without redoing the proof-of-work.Immutable. No one can change the Bitcoin transaction that happened. At all.The longest chain not only serves as proof of the sequence of events witnessed, but proof that it came from the largest pool of CPU power.Satoshi didn’t foresee the mining pool oligopoly that permeates Bitcoin and most Proof of Work cryptocurrencies today.As long as a majority of CPU power is controlled by nodes that are not cooperating to attack the network, they'll generate the longest chain and outpace attackers.What does controlled by nodes mean? Many people run nodes but only a few mining pools mine almost all the Bitcoin.This is also known as the 51% attack. But you just need one more node than 50% (e.g., 50% + 1) so it is more accurately a majority attack.The network itself requires minimal structure.Because?Messages are broadcast on a best effort basis, and nodes can leave and rejoin the network at will, accepting the longest proof-of-work chain as proof of what happened while they were gone.As Alex Seewald notes in the comments below, Satoshi is probably referring to best effort delivery. Best-effort delivery - WikipediaWho is doing the broadcasting?Like everything else in Bitcoin, you as a runner of full nodes are free to come and go as you please. That’s why many Bitcoin maximalists argue Bitcoin Core is not centralized.However, others disagree.Quantifying Decentralization – news.earn.com1. IntroductionCommerce on the Internet has come to rely almost exclusively on financial institutions serving as trusted third parties to process electronic payments.I think Satoshi is anti-bank, anti-PayPal and anti-Western Union. This is one reason why.While the system works well enough for most transactions, it still suffers from the inherent weaknesses of the trust based model.A key facet of Bitcoin is that it is trustless. You don’t have to trust JP Morgan.Completely non-reversible transactions are not really possible, since financial institutions cannot avoid mediating disputes.Unlike Bitcoin.The cost of mediation increases transaction costs, limiting the minimum practical transaction size and cutting off the possibility for small casual transactions, and there is a broader cost in the loss of ability to make non-reversible payments for non- reversible services.Debit cards payments are hard to reverse. Cash payments are even harder to reverse. Especially when either is combined with an “All Sales Final” condition.With the possibility of reversal, the need for trust spreads.Yes and many Americans prefer trusting American Express’ customer service over some random merchant on the internet that might rip you off.Merchants must be wary of their customers, hassling them for more information than they would otherwise need.BItcoin is just reallocating the risk from merchants back to consumers. It’s kind of anti-consumer tbh.A certain percentage of fraud is accepted as unavoidable.Yes, just like how so many of my friends have lost some crypto stolen or lost. Seems unavoidable!These costs and payment uncertainties can be avoided in person by using physical currency, but no mechanism exists to make payments over a communications channel without a trusted party.He should have said much earlier, “Unlike physical currency…”What is needed is an electronic payment system based on cryptographic proof instead of trust, allowing any two willing parties to transact directly with each other without the need for a trusted third party.Proof of work.Transactions that are computationally impractical to reverse would protect sellers from fraud, and routine escrow mechanisms could easily be implemented to protect buyers.Decentralized escrow? Are buyers to trust a third party centralized escrow service over American Express? As a buyer, I’m not doing that.In this paper, we propose a solution to the double-spending problem using a peer-to-peer distributed timestamp server to generate computational proof of the chronological order of transactions.Making it easier to follow the money i mean Bitcoin.The system is secure as long as honest nodes collectively control more CPU power than any cooperating group of attacker nodes.Bitcoin relies (trust?) the majority of full node runners to be honest. Here’s hoping mob rule, centralized mining or mass hysteria never takes over.2. TransactionsWe define an electronic coin as a chain of digital signatures.Very unexpected IMO. How is this anything like a normal coin? It is a ledger ledger of all the transactions relating to one asset, which isn’t even totally fungible with others. It seems we can literally give you the coin from Satoshi’s genesis block or another coin that we all know was mined today by F2Pool or whatever.Each owner transfers the coin to the next by digitally signing a hash of the previous transaction and the public key of the next owner and adding these to the end of the coin.Moving the digital signatures off the main chain is a bit scary to some folks - that’s why some dislike SegWit - which does that.A payee can verify the signatures to verify the chain of ownership.Who the heck wants to do an electronic title search every time they spend $100 of Bitcoin? This makes sense for big purchases like real estate and collectibles but not for small or even medium sized purchases.I’m not sure how pragmatic Satoshi was. He built great tech. He was not as great at guessing use cases and what unmet, urgent need Bitocin actually meets.Transaction[Would love it if someone can please help me and copy paste in the diagrams.]Owner 0's SignatureOwner 1's Private KeyTransactionOwner 1's SignatureOwner 2's Private KeyTransactionOwner 2's SignatureOwner 1's Public KeyOwner 2's Public KeyOwner 3's Public KeyHashHashHashThe problem of course is the payee can't verify that one of the owners did not double-spend the coin.Satoshi focuses a lot on double spending.A common solution is to introduce a trusted central authority, or mint, that checks every transaction for double spending.Mints and the entity that checks for double spending can be two different entities, no? In the analog world, the US government prints money. Maybe a private third party company like a PayPal checks for double spending among its users and customers.After each transaction, the coin must be returned to the mint to issue a new coin, and only coins issued directly from the mint are trusted not to be double-spent.This is bad if you believe, like Ray Dalio, government should increase the money supply (issue new coins) when no one’s spending, everyone’s HODLing and the token economy is shrinking. And you should decrease money suply (burn coins) if there is high or hyperinflation.The problem with this solution is that the fate of the entire money system depends on the company running the mint, with every transaction having to go through them, just like a bank.Broadly speaking, we have not really gotten away from that in Bitcoin. We just replaced banks with centralized mining chip makers, mining pools, developers, maintainers, client implementations, exchanges, wallets, owners, etc.We need a way for the payee to know that the previous owners did not sign any earlier transactions.This seems like a total pain. No wonder Hashcash didn’t work.For our purposes, the earliest transaction is the one that counts, so we don't care about later attempts to double-spend.What are the implications of this, if any?The only way to confirm the absence of a transaction is to be aware of all transactions.Awful.In the mint based model, the mint was aware of all transactions and decided which arrived first.To accomplish this without a trusted party, transactions must be publicly announced [1], and we need a system for participants to agree on a single history of the order in which they were received.The payee needs proof that at the time of each transaction, the majority of nodes agreed it was the first received.3. Timestamp ServerThe solution we propose begins with a timestamp server.A timestamp server works by taking a hash of a block of items to be timestamped and widely publishing the hash, such as in a newspaper or Usenet post [2-5].Hmmm…The timestamp proves that the data must have existed at the time, obviously, in order to get into the hash.Each timestamp includes the previous timestamp in its hash, forming a chain, with each additional timestamp reinforcing the ones before it.Owner 3's Private KeyHashHashBlock2BlockItemItem...ItemItem...VerifyVerifySignSign4. Proof-of-WorkTo implement a distributed timestamp server on a peer-to-peer basis, we will need to use a proof- of-work system similar to Adam Back's Hashcash [6], rather than newspaper or Usenet posts.Adam is the relatively (compared to unctuous CTO Greg Maxwell) cypherpunk and CEO of the controversial Blockstream, funded in part by Tencent in China.The proof-of-work involves scanning for a value that when hashed, such as with SHA-256, the hash begins with a number of zero bits.The average work required is exponential in the number of zero bits required and can be verified by executing a single hash.For our timestamp network, we implement the proof-of-work by incrementing a nonce in the block until a value is found that gives the block's hash the required zero bits.[Can someone help translate all this into plain English?]Once the CPU effort has been expended to make it satisfy the proof-of-work, the block cannot be changed without redoing the work.Immutable.As later blocks are chained after it, the work to change the block would include redoing all the blocks after it.The proof-of-work also solves the problem of determining representation in majority decision making.If the majority were based on one-IP-address-one-vote, it could be subverted by anyone able to allocate many IPs.Wonder what Satoshi thought of Proof of Stake at the time he wrote the white paper in 2008.Proof-of-work is essentially one-CPU-one-vote.Does hash rate matter more than full nodes?The majority decision is represented by the longest chain, which has the greatest proof-of-work effort invested in it.Some developers like Gavin Andressen IIRC tweeted that the real Bitcoin is the one with the longest chain, and that might be Bitcoin Cash.If a majority of CPU power is controlled by honest nodes, the honest chain will grow the fastest and outpace any competing chains.This is why small blockers want to ensure that blocksizes per second remain small - or become even smaller - so that many people - not just miners - can run full nodes and keep miners honest and reduce the risk of miners colluding and engaging a majority attack.To modify a past block, an attacker would have to redo the proof-of-work of the block and all blocks after it and then catch up with and surpass the work of the honest nodes.It would appear that Bitcoin is only immutable to the extent that most of the CPU power is controlled by honest nodes.We will show later that the probability of a slower attacker catching up diminishes exponentially as subsequent blocks are added.Arguably Bitcoin becomes harder to attack as blocks grow.To compensate for increasing hardware speed and varying interest in running nodes over time, the proof-of-work difficulty is determined by a moving average targeting an average number of blocks per hour. If they're generated too fast, the difficulty increases.5. NetworkThe steps to run the network are as follows:1) New transactions are broadcast to all nodes.2) Each node collects new transactions into a block.3) Each node works on finding a difficult proof-of-work for its block.4) When a node finds a proof-of-work, it broadcasts the block to all nodes.5) Nodes accept the block only if all transactions in it are valid and not already spent.6) Nodes express their acceptance of the block by working on creating the next block in the chain, using the hash of the accepted block as the previous hash.Nodes always consider the longest chain to be the correct one and will keep working on extending it. If two nodes broadcast different versions of the next block simultaneously, some nodes may receive one or the other first. In that case, they work on the first one they received, but save the other branch in case it becomes longer. The tie will be broken when the next proof- of-work is found and one branch becomes longer; the nodes that were working on the other branch will then switch to the longer one.3BlockBlockPrev HashNoncePrev HashNonceTxTx...TxTx...New transaction broadcasts do not necessarily need to signNow all nodes. As long as they signNow many nodes, they will get into a block before long. Block broadcasts are also tolerant of dropped messages. If a node does not receive a block, it will request it when it receives the next block and realizes it missed one.6. IncentiveBy convention, the first transaction in a block is a special transaction that starts a new coin owned by the creator of the block. This adds an incentive for nodes to support the network, and provides a way to initially distribute coins into circulation, since there is no central authority to issue them. The steady addition of a constant of amount of new coins is analogous to gold miners expending resources to add gold to circulation. In our case, it is CPU time and electricity that is expended.The incentive can also be funded with transaction fees. If the output value of a transaction is less than its input value, the difference is a transaction fee that is added to the incentive value of the block containing the transaction. Once a predetermined number of coins have entered circulation, the incentive can transition entirely to transaction fees and be completely inflation free.The incentive may help encourage nodes to stay honest. If a greedy attacker is able to assemble more CPU power than all the honest nodes, he would have to choose between using it to defraud people by stealing back his payments, or using it to generate new coins. He ought to find it more profitable to play by the rules, such rules that favour him with more new coins than everyone else combined, than to undermine the system and the validity of his own wealth.7. Reclaiming Disk SpaceOnce the latest transaction in a coin is buried under enough blocks, the spent transactions before it can be discarded to save disk space. To facilitate this without breaking the block's hash, transactions are hashed in a Merkle Tree [7][2][5], with only the root included in the block's hash. Old blocks can then be compacted by stubbing off branches of the tree. The interior hashes do not need to be stored.BlockBlock Header (Block Hash)Prev HashNonceRoot HashHash01Hash23Hash0Hash1Hash2Hash3Tx0Tx1Tx2Tx3BlockBlock Header (Block Hash)Prev HashNonceRoot HashHash01Hash23Hash2Hash3Tx3Transactions Hashed in a Merkle Tree After Pruning Tx0-2 from the BlockA block header with no transactions would be about 80 bytes. If we suppose blocks are generated every 10 minutes, 80 bytes * 6 * 24 * 365 = 4.2MB per year. With computer systems typically selling with 2GB of RAM as of 2008, and Moore's Law predicting current growth of 1.2GB per year, storage should not be a problem even if the block headers must be kept in memory.48. Simplified Payment VerificationIt is possible to verify payments without running a full network node. A user only needs to keep a copy of the block headers of the longest proof-of-work chain, which he can get by querying network nodes until he's convinced he has the longest chain, and obtain the Merkle branch linking the transaction to the block it's timestamped in. He can't check the transaction for himself, but by linking it to a place in the chain, he can see that a network node has accepted it, and blocks added after it further confirm the network has accepted it.Longest Proof-of-Work ChainBlock HeaderBlock HeaderBlock HeaderPrev HashNoncePrev HashNoncePrev HashNonceMerkle RootMerkle RootMerkle RootHash01 Hash23Merkle Branch for Tx3Hash2 Hash3Tx3As such, the verification is reliable as long as honest nodes control the network, but is more vulnerable if the network is overpowered by an attacker. While network nodes can verify transactions for themselves, the simplified method can be fooled by an attacker's fabricated transactions for as long as the attacker can continue to overpower the network. One strategy to protect against this would be to accept alerts from network nodes when they detect an invalid block, prompting the user's software to download the full block and alerted transactions to confirm the inconsistency. Businesses that receive frequent payments will probably still want to run their own nodes for more independent security and quicker verification.9. Combining and Splitting ValueAlthough it would be possible to handle coins individually, it would be unwieldy to make a separate transaction for every cent in a transfer. To allow value to be split and combined, transactions contain multiple inputs and outputs. Normally there will be either a single input from a larger previous transaction or multiple inputs combining smaller amounts, and at most two outputs: one for the payment, and one returning the change, if any, back to the sender.It should be noted that fan-out, where a transaction depends on several transactions, and those transactions depend on many more, is not a problem here. There is never the need to extract a complete standalone copy of a transaction's history.5TransactionInOutIn......10. PrivacyThe traditional banking model achieves a level of privacy by limiting access to information to the parties involved and the trusted third party. The necessity to announce all transactions publicly precludes this method, but privacy can still be maintained by breaking the flow of information in another place: by keeping public keys anonymous. The public can see that someone is sending an amount to someone else, but without information linking the transaction to anyone. This is similar to the level of information released by stock exchanges, where the time and size of individual trades, the "tape", is made public, but without telling who the parties were.Traditional Privacy ModelTransactionsNew Privacy ModelIdentities TransactionsAs an additional firewall, a new key pair should be used for each transaction to keep them from being linked to a common owner. Some linking is still unavoidable with multi-input transactions, which necessarily reveal that their inputs were owned by the same owner. The risk is that if the owner of a key is revealed, linking could reveal other transactions that belonged to the same owner.11. CalculationsWe consider the scenario of an attacker trying to generate an alternate chain faster than the honest chain. Even if this is accomplished, it does not throw the system open to arbitrary changes, such as creating value out of thin air or taking money that never belonged to the attacker. Nodes are not going to accept an invalid transaction as payment, and honest nodes will never accept a block containing them. An attacker can only try to change one of his own transactions to take back money he recently spent.The race between the honest chain and an attacker chain can be characterized as a Binomial Random Walk. The success event is the honest chain being extended by one block, increasing its lead by +1, and the failure event is the attacker's chain being extended by one block, reducing the gap by -1.The probability of an attacker catching up from a given deficit is analogous to a Gambler's Ruin problem. Suppose a gambler with unlimited credit starts at a deficit and plays potentially an infinite number of trials to try to signNow breakeven. We can calculate the probability he ever signNowes breakeven, or that an attacker ever catches up with the honest chain, as follows [8]:p = probability an honest node finds the next block q = probability the attacker finds the next block qz = probability the attacker will ever catch up from z blocks behindIdentitiesTrusted Third PartyPublicq ={ 1 if p≤q} z q/pz if pq6CounterpartyPublicGiven our assumption that p > q, the probability drops exponentially as the number of blocks the attacker has to catch up with increases. With the odds against him, if he doesn't make a lucky lunge forward early on, his chances become vanishingly small as he falls further behind.We now consider how long the recipient of a new transaction needs to wait before being sufficiently certain the sender can't change the transaction. We assume the sender is an attacker who wants to make the recipient believe he paid him for a while, then switch it to pay back to himself after some time has passed. The receiver will be alerted when that happens, but the sender hopes it will be too late.The receiver generates a new key pair and gives the public key to the sender shortly before signing. This prevents the sender from preparing a chain of blocks ahead of time by working on it continuously until he is lucky enough to get far enough ahead, then executing the transaction at that moment. Once the transaction is sent, the dishonest sender starts working in secret on a parallel chain containing an alternate version of his transaction.The recipient waits until the transaction has been added to a block and z blocks have been linked after it. He doesn't know the exact amount of progress the attacker has made, but assuming the honest blocks took the average expected time per block, the attacker's potential progress will be a Poisson distribution with expected value:=z q pTo get the probability the attacker could still catch up now, we multiply the Poisson density for each amount of progress he could have made by the probability he could catch up from that point:∞ ke−{q/pz−k ifk≤z} ∑k=0 k!⋅ 1 ifkzRearranging to avoid summing the infinite tail of the distribution...z ke− z−k 1−∑k=0 k! 1−q/p Converting to C code... #include
double AttackerSuccessProbability(double q, int z) { double p = 1.0 - q; double lambda = z * (q / p); double sum = 1.0; int i, k; for (k = 0; k <= z; k++) { double poisson = exp(-lambda); for (i = 1; i <= k; i++) poisson *= lambda / i; sum -= poisson * (1 - pow(q / p, z - k)); }return sum; }7Running some results, we can see the probability drop off exponentially with z. q=0.1 z=0 P=1.0000000 z=1 P=0.2045873 z=2 P=0.0509779 z=3 P=0.0131722 z=4 P=0.0034552 z=5 P=0.0009137 z=6 P=0.0002428 z=7 P=0.0000647 z=8 P=0.0000173 z=9 P=0.0000046 z=10 P=0.0000012 q=0.3 z=0 P=1.0000000 z=5 P=0.1773523 z=10 P=0.0416605 z=15 P=0.0101008 z=20 P=0.0024804 z=25 P=0.0006132 z=30 P=0.0001522 z=35 P=0.0000379 z=40 P=0.0000095 z=45 P=0.0000024 z=50 P=0.0000006 Solving for P less than 0.1%... P < 0.001 q=0.10 z=5 q=0.15 z=8 q=0.20 z=11 q=0.25 z=15 q=0.30 z=24 q=0.35 z=41 q=0.40 z=89 q=0.45 z=340 12. ConclusionWe have proposed a system for electronic transactions without relying on trust. We started with the usual framework of coins made from digital signatures, which provides strong control of ownership, but is incomplete without a way to prevent double-spending. To solve this, we proposed a peer-to-peer network using proof-of-work to record a public history of transactions that quickly becomes computationally impractical for an attacker to change if honest nodes control a majority of CPU power.Do coins have a majority of CPU power?The network is robust in its unstructured simplicity. Nodes work all at once with little coordination. They do not need to be identified, since messages are not routed to any particular place and only need to be delivered on a best effort basis. Nodes can leave and rejoin the network at will, accepting the proof-of-work chain as proof of what happened while they were gone. They vote with their CPU power, expressing their acceptance of valid blocks by working on extending them and rejecting invalid blocks by refusing to work on them.Any needed rules and incentives can be enforced with this consensus mechanism.The controversial UASF (User Activated Soft Fork) push for SegWit was arguably an example of consensus and honest folk running full nodes forcing the Bitcoin community (miners) to make SegWit an option for users, merchants, exchanges, etc. and pave the way for SegWit adoption.8References[1] W. Dai, "b-money," http://www.weidai.com/bmoney.txt, 1998.[2] H. Massias, X.S. Avila, and J.-J. Quisquater, "Design of a secure timestamping service with minimal trust requirements," In 20th Symposium on Information Theory in the Benelux, May 1999.[3] S. Haber, W.S. Stornetta, "How to time-stamp a digital document," In Journal of Cryptology, vol 3, no 2, pages 99-111, 1991.[4] D. Bayer, S. Haber, W.S. Stornetta, "Improving the efficiency and reliability of digital time-stamping," In Sequences II: Methods in Communication, Security and Computer Science, pages 329-334, 1993.[5] S. Haber, W.S. Stornetta, "Secure names for bit-strings," In Proceedings of the 4th ACM Conference on Computer and Communications Security, pages 28-35, April 1997.[6] A. Back, "Hashcash - a denial of service counter-measure," http://www.hashcash.org/papers/h..., 2002.[7] R.C. Merkle, "Protocols for public key cryptosystems," In Proc. 1980 Symposium on Security and Privacy, IEEE Computer Society, pages 122-133, April 1980.[8] W. Feller, "An introduction to probability theory and its applications," 1957.9
Trusted esignature solution— what our customers are saying
Get legally-binding signatures now!
Related searches to Remove Electronic signature Form Later
Frequently asked questions
How do i add an electronic signature to a word document?
How to sign a pdf in paint?
What text do i put for an electronic signature?
Get more for Remove Electronic signature Form Later
- Help Me With Electronic signature Hawaii Sports Presentation
- How Can I Electronic signature Hawaii Sports Presentation
- Can I Electronic signature Hawaii Sports Presentation
- How To Electronic signature Hawaii Sports Presentation
- How Do I Electronic signature Hawaii Sports Presentation
- Help Me With Electronic signature Hawaii Sports Presentation
- How Can I Electronic signature Hawaii Sports Presentation
- Can I Electronic signature Hawaii Sports Presentation
Find out other Remove Electronic signature Form Later
- Vaccine storage troubleshooting record check one form
- Investment management liability solutions application cna pro form
- Form 1125 a
- Thank you very much for your interest in the willed body donation ghs form
- High adventure activity medical form health examination to be ahgonline
- Health form network
- Medical encounter form
- Excellus authorization to print out 2007 form
- Fillable mra form
- Midland national beneficiary change form
- Dexcom order form certificate of medical necessity
- Disability benefit claim form
- Cigna forms for providers
- Abreivement form
- Hospital discharge template form
- Fillable health carfe questionaire form
- Blank power of attorney forms printable
- Membership application mc vanderbilt form
- Tricare worksheet form
- Concede vs consent form