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FAQs
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What are the steps for a new company registration in India?
With reference to this blog - The Companies (Amendment) Act, 2017 - What Startups should know?There has been majorly 15 changes to the companies Act, 2017. But, from registration point of view, there has been just 2 changes -With reference to this blog: Reserve Unique Name electronicallyThe Ministry has also introduced Reserve Unique Name (RUN) forms to simplify the name reservation process of a company.The rules earlier required a company to reserve a name either in advance through the Name Reservation — INC-1 form or directly through the incorporation application (SPICe Form).Now, the RUN form has replaced the INC-1 form.Other features include:RUN form gives the option for only one name for the company, unlike INC-1 which had a provision of six options for the company’s name.RUN form doesn’t require any Director Identification Number (DIN) or a Digital Signature Certificate (DSC)The fees for RUN form is $15.7 (INR 1000), irrespective of whether the name is approved or notThe approved name is valid for up to 20 days and 60 days from the date of approval for a new company and an existing company, respectively.The proposed companies can apply for the reservation of name using the RUN form and they will be intimated of the approval by the MCA through email. However, it has been suggested that RUN form be used when there is an ambiguity about the name because of its similarity to existing companies or Limited Liability Partnerships (LLPs).If the name is unique, a company can apply for the name directly with the SPICe form. This would save time and money for the applying company.e reservation - RUN. Registration fees (Government fees) has been removed.2. With reference to this blog “Zero Registration Fees”The Ministry has amended the fees payable to the Registrar to incorporate the companies.The Companies claimed the benefit of Zero Fees for incorporation shall maintain the status of small companies till one year. Therefore, the companies could not increase its Authorized Capital above INR 10 lakh within the span of 1 year from its incorporation.The fees payable to States were not reduced or eliminated i.e. the Stamp Duty on MoA and AoA of the companies would stay intact.Charges that remain in place are:Fee for Company Name ApplicationCompany Registration Fee (Based on Authorised Capital / Number of Members of the Company on Memorandum – Form No.INC-32-SPICe),Filing Fee for documents such as Memorandum of Association (Form No.INC-33-SPICe) and Articles of Association (Form No.INC-34-SPICe),Stamp duty payable to the state government on registration of Memorandum and Articles of Association based on authorized capital, declarations, affidavits etc.But the procedure to register a private limited company or an OPC still remains the same.
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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
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You have been contracted to build the world’s first modern battleship since the 1940s with a budget similar to what went into th
The class would be known as the Superior class battleship thanks to input by Brayden Swanson named after the great lakes.The first ship would be known as the USS Superior, named after lake superior, because in my opinion it’s a very superior ship design. (yes, I say so myself, but I spent too much time on this so I’m proud of it. )So my design isn’t going to be your traditional big gun warship because at this point while big guns are great at gunfire support they lack the range to strike far inshore and are quite inaccurate designed to saturate entire map grids leaving nothing standing, but...
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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 :)
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The income tax department has segregated the taxpayer based on their status, source of income , basis of income and other factors. Taxpayer having taxable income are required to file income tax return based on their incomes.ITR 2 is to be filed by individual or HUF (not having income from PGBP ) and not eligible to file ITR 1ITR 1 is to be filed by individual or HUF having total income upto Rs 50L from salary, 1 HP and other sources. Agriculture income should not exceed Rs 5000.ITR 2 can be downloaded and submitted on the income tax website . After successful filing an acknowledgement will be sent to your registered email id which can also be downloaded manually.There are certain category of people who can also submit the return offline.For AY 18–19 , the last day of filing ITR 2 is 31st July 2018 . If it is filed after the due date penalty under Section 234F will be levied.
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What is the best free PDF reader for large documents?
[1] PDF format is popularly known as print document format. This creates a virtual printer within operating system to print the document. For offline scanning of document, the PDF format is popular. The importance attached with these program is that you need to have PDFsoftware installed to run these files. If someone sends you PDF file and your computer do not have such software installed then that file is not to be read from there.There are so many PDF softwires available and this article aims to find out the mostly free software or freeware to help readers to choose from variety of options. More and more operating systems are providing built-in facilities for such products. Now-a-days everything comes with PDF formats beginning from circulars, bank statement, insurance statement, tax statement and e-books.That is why there immense important to have the free PDF software installed on computer but the thousand question is which one is to choose from the variety of resources available.Sumatra PDF:Sumatra PDF is available for download to Windows since the times of Windows XP. This program has very low foot print, light on system resources and fast. It is going to perform simple task as well as it is going to perform complex task depending upon you choose from PDFfiles. It is available with installed version as well as standalone portable version in which it does not write to registry.It is available in 64 bit version on Windows. It is available for Windows XP, Vista, 7, 8, 8.1 and 10. It is available for Windows operating system only.signNow Reader DC:It is from signNow and signNow is available for free for users. While installing this software do check for installation of MCAfee security and safe connect.it is a big download of nearing to 120 MB. Yours antivirus software might stop this installation so allow to install it. This software for high=end computing processes.Many features are included with it and for some features you might need it and if you want to have these features then it is better to choose this software. It has mobile version of android and apple operating system. With it you are going to synchronize documents with clouds and yours signature too and everything is going to stay with cloud to access from each and every device.When you first download signNow on Windows, a download manager first downloads and it is small in size and then by opening that download manager signNow software is installed and this is nearer to 120 MB.PDF-Xchange Editor:PDF-Xchange Editor is a smart PDF tools and most functions are free except some complex ones. It is a PDF reader, pdf editor and pdf tools. It can print PDFs, fill the forms created with signNow and can extract images from PDF files. There are some advanced features included in this free version but most of these are not free one is that watermarking of PDFsoftware which is not free.Foxit Reader:Foxit Reader is fast, simple and is there for years. It is available for Windows, Apple and android versions. It can fill forms and save data. Can include and validate electronic signatures. During installation user need to be cautioned not to install so many verities of other software. In order to keep the size of download minimal, the user manual is available for separate download.It is faster than PDF-Xchange Editor. If you are not interested in OCR facilities then Foxit reader is best suited for yours work. Multiple PDF documents when opened all these are opened in tab format and shifting from one tab to the other is easier. From time to time it introduces some new features in order to provide dynamic software development.It allows adding up of multimedia files easier. Collaboration with social media accounts becomes easier with Fixit Reader because of the ease to synchronize with Twitter, Facebook, Evernote and SharePoint. One caution is that Foxit Reader comes bundled with so many other software and toolbar and it is important to not to allow installations of such software during its installation.MuPDF Reader:It is very lightweight PDF Reader. On its first launch it will ask you about to choose from files instead of showing its interface and when the PDF is opened then it shows the exact documents and no toolbar and other interfaces are present. In order to see the interface of MuPDF reader you are going to click on the top left of the visible windows to find it. It provides a cleaner interface and superior look for PDF files.Google Chrome PDF viewer:While browsing for internet whenever you see any PDF and click on it and it will slowly open in another tab of Chrome and you can read it from there or download by clicking the downloadsymbol available there. This setting can be turned and changed out there easily, go to settings of chrome and then advanced and then content settings and then pdf documents, Scroll down and click on PDF documents and from there switch on ‘Download PDF files instead of opening automatically opening them in Chrome’ and this will download PDF files from net to computer.If you want to read PDF files that are stored inside computer, then right click on that files and then open with chrome and your chrome reader will automatically, open pdf files and for this you will not have to install pdf viewers. Similarly, with android if you install Google Drive then you will not need any other third-party PDF apps as Google Drive act as PDF viewer and make it default while opening the first PDF and that is going to make it default.TinyPDF:TinyPDF as the name suggests has very small foot print of PDF reader and it has no string attached. It is only 586k as it is less than one MB. It does not contain no malware, adware, watermarks and no pop Global Home: UPS is completely free. JPEG compression is supported. No ghost script and third-party software included with the installer version. The downside is that it is partially supported on 64-bit computer. Automatic font management is there.There are so many alternatives to use for PDF viewer and if your computer is 64 bit then you can download the 64 bit version of Sumatra PDF and if you want to insert electronic signature then opt for Foxit PDF reader and if you want to have the old and classic PDF reader which is heavier in file composition and not for low end computing purposes then go for signNow and lastly if you do not want to install PDF readers at all then it is better to open it with Google Chrome built in PDF viewer.So, there are many large numbers of option to choose from and if you want to have some complex PDF functions besides the presence of PDF reader you need pdf tools and others then it is best to have PDF-Xchange viewer and so many other option listed here you can choose it from. There are some other alternatives are available which are there to search ad find in internet.This entry was posted in Android Apps on Google Play, Apple Inc., Computer Information Technology, Google, Google Chrome, Information Technology, Internet, Windows 10, Windows 8, Windows XP and tagged signNow, Apple, doPDF, FOXIT READER, free PDF converter, google chrome, image to pdf converter, PDF Password Remover, pdf printer, pdf-xchange, Sumatra PDF A PDF Viewer for Windows, WINDOWS, Windows 8, WINDOWS VISTA, WINDOWS XP, Windows XP SP3 onFootnotes[1] Best Free PDF Writer and Reader
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Is Maduro a dictator?
Nicolás Maduro is a dictator. Rosa Lichtenstein has absolutely no idea what she’s talking about, just like anybody who affirms that Maduro is a democratically elected leader.Maduro has turned every election since April 14, 2013 into an electoral sham. He does not have enough support to win an election democratically, and has never had it.As a consequence, Maduro lacks legitimacy of origin, and because of his regime’s violent repression of political opposition activists, which are subject to persecution, exile, torture and even murder it has no legitimacy of exercise.Maduro is a dictator, and a bloody one at that.If you want to get a gist of the Venezuelan ‘electoral’ process:People are intimidated into voting for the chavista candidate, whoever it is. The regime holds databases of people who are members of the Socialist Party as well as databases for every Venezuelan who receives a form of social assistance. If you don’t show up to vote when they call you, they threaten with taking social welfare benefits away from you. This is a systematic practice.The Maduro regime relies on civilian militias that are ideologically aligned with it. These are the círculos bolivarianos or the ‘colectivos’. The colectivos (collectives) are meant to ‘defend the revolution’. Every Election Day, not only under Maduro but also under Chávez, these groups come out to intimidate voters in opposition-leaning electoral precincts.The CNE (Consejo Nacional Electoral) or the National Electoral Council is not an independent election supervising organism. Out of its five directors, at least four are known to be subservient to the Maduro regime. Bear in mind that Venezuela has an all-electronic voting system that has never been audited independently because the CNE will not allow it to be. If there’s nothing to hide, then why do they have to be so secretive?The National Electoral Council also controls which parties can run for elections, and most recently the vast majority of the opposition parties were illegalized, and subjected to a “relegalization” process that meant that they had to recognize the validity of Maduro’s unconstitutional National Constituent Assembly. Naturally, only the most opportunistic political parties were relegalized.Because Venezuela’s judiciary is not independent, political leaders who can pose a real challenge to Maduro or to any other chavista candidate are barred from running. How? They’re politically inhabilitated, which means they cannot run or hold public office. The Venezuelan opposition’s three main national leaders: Leopoldo López, María Corina Machado and Henrique Capriles Radonski have all been politically inhabilitiated by the regime. Is this an election? Only if you would call an election one in which the incumbent gets to chose who he runs against.The press is not free. As a consequence, opposition candidates are at a great disadvantage because: they’re invisibilized by the public media and the so-called private media that by now is largely in the hands of people who act as frontmen to the chavistas, and who owe their newly acquired fortunes to their political connections.Venezuela will not allow independent international observers to follow the electoral process on the ground.There are reasons to believe that the electoral process is structurally compromised. What I mean by this is that the outcome of the elections can be changed. In addition to the voting system not being audited properly, a number of us have suspected and denounced electronic manipulation of the vote count since 2004. In the case of the 2004 election, Venezuelan statisticians Delfino and Salas published a study that not only detailed how the CNE self sabotaged its two audits but also found a linear correlation between votes in favor of removing Hugo Chavez from office and the number of signatures that were collected to call the referendum. They suggest that this is strange. I think it’s much more than strange, especially in light of the fact that the correlation is seen largely on electoral precincts where the vote was 100% electronic and the voting machines were connected with the CNE servers prior to the final vote count.See: Delfino and Salas: A Closer Look at the 2004 election - Provided by Cornell University LibraryThe Official Results Versus the Petition SignaturesIf these sound like free and fair elections to you, you need to revise your meaning of free and fair.
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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.
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