• A Skeptical Look At the Possibility of Life on Other Planets

    There were several interesting articles and images that all gave me the inspiration for this post. So, let’s talk about the idea of life in our universe beyond our solar system.

    The first question to think about is how many other planets are there. The answer is lots. No, “lots” doesn’t even begin to cover it. I got this image from NASA (click the image to the source… it’s big).

    Hubble deep field image. NASA
    Hubble deep field image. NASA

    Phil Plait, over at Bad Astronomy did a calculation to determine just how many galaxies Hubble could see. Note that isn’t all the galaxies in the universe, just the ones the Hubble Space Telescope could potentially see.

    First he calculated how many galaxies were in a small piece of the above image. It’s about 50. That piece was 1/100 of the actual image. So, the image above contains about 5,000 galaxies.

    Then he found out that the image is 10 square arcminutes. The entire sky is about 150 million square arcminutes, which means that there are about 15,000,000 pieces of sky the same size as the above image. At roughly 5,000 galaxies per, we get a total of 75,000,000,000 galaxies. That’s 75 billion visible galaxies with the Hubble.

    The Milky Way has about 100 billion stars (though some estimates approach 400 billion).  If we assume that an average galaxy has 100 billion stars, which is fairly safe, then we get 100 billion * 75 billion stars in the universe.

    That is 7,500,000,000,000,000,000,000 or 7.7×1021 stars.

    How many could potentially support life? Well, a lot depends on A) how you define life and B) what conditions we consider for that life.

    Right now, we know of only one planet that unambiguously has life. There is significant potential for life elsewhere in our solar system. Though it would likely be limited to the bacteria level or extraterrestrial equivalent. Still, if we find life on Europa, Titan, Enceladus, or even Mars, then the options for life on extrasolar planets just got even better.

    But let’s talk about that life on other planets. How would life appear?

    Well, that’s an entire topic of research called Origins of Life (OOL). The results are very impressive so far. There are multiple ways to get the basic organic compounds needed for life, without life needing to be present. One of the main sticking points has been ribose sugars, the main component in the backbone of DNA and RNA. Some new research suggests that is much less of a sticking point than previously thought.

    Cornelia Meinert (Meinert 2016) and her team discovered that a relatively simple reaction, catalyzed by ultraviolet light, forms ribose and a variety of other sugars… in space.

    Ice is common in space, we regularly track large balls of space ice and even landed on one of them. So, that’s water. Another needed component is ammonia, which seems to be common in space as well. Finally, we need a source of carbon and that comes from methanol (methyl alcohol). Which is, you guessed it, common in deep space. These are all inorganic sources of these materials, no life required.

    The idea behind the paper is that a planetary nebula, that is a pre-solar system, has all these materials much more scattered than in a solar system with planets. There’s a lot of supporting evidence for this in our own solar system.

    In our solar system, excluding the sun, Jupiter has 3 times the mass of every other planet combined. It has methane, ammonia (including ammonia ice), even benzene rings (link to Voyager probe results). So, in a pre-planetary nebula, all of these compounds would be present.

    Much like the famous Miller-Urey experiment, the researchers took these compounds, exposed them to near space temperatures (78 Kelvin, which is -319 F), hit them with UV light, then warmed them up. The result was 56 unique compounds (not including the isomers of those compounds), most of which, we would think required life to manufacture.

    The question then becomes, how did the material formed in space get to Earth. That’s where the Late-Heavy Bombardment comes in. The hypothesis is that between 4.1 and 3.8 billion years ago, the inner planets underwent a very heavy period of asteroid and comet impacts. The suggested impacts are stunning. By extrapolating lunar impacts to Earth, the estimate is over 20,000 impacts large enough to form a 20 kilometer diameter crater. As an example, Meteor Crater in Arizona is just over 1 kilometer in diameter.

    Larger impacts would also have happened, including multiple impacts resulting in 5,000 kilometer craters.

    This is in addition to other research about the common origin of RNA, lipids, and proteins.

    The point is, we find these compounds all over the universe. And the universe is truly immense. It is the height of arrogance to assume that life only exists on Earth and that humans are the only intelligent species in the universe.

    Now, a discussion about whether we would ever find that other life is a totally different prospect. But even with one planet per galaxy with life, that’s 75 billion planets with life in our universe.


    Meinert, C, Myrgorodska, I & Marcellus, D. P. Ribose and related sugars from ultraviolet irradiation of interstellar ice analogs. … (2016). doi:10.1126/science.aad8137

    Category: BiologyChemistryfeaturedOrigins of LifeResearchScience


    Article by: Smilodon's Retreat

    • Doc Bill

      My favorite subject! Recent discoveries indicate that every star could have planets. That’s quite a different estimate than the original Drake Equation.

      Self-sustaining chemical reactions became established on Earth something like a billion years after the planet formed. It could be that this kind of chemistry is the expected outcome rather than the exception.

    • ubishere

      The possibilities of intelligent life are pretty convincing which leads me to believe at some stage an alien race has invented an ASI (Artificial Super intelligence) computer.

      With the law of accelerating returns the ASI could self improve at an astronomical rate, utilising nano type technologies, designing advanced manufacturing processes and power plants in its initial development.

      On an on it goes – an omnipotent god like being with the ability to decipher and manipulate the universe in ways we cannot comprehend, given enough time it would eventually have a total understanding of everything.

      Once it learns how to bend/manipulate time and/or transverse dimensions then It wouldn’t matter when it was created, only that it was created. Obviously at some stage it creates and ignites the ‘big bang’ payload and creates the very universe in which it was created.

      I am not a creationist in the sense of believing religious stories in old books, I doubt such an entity would really take any interest in the individual day-to-day lives of billions of primates living on this planet, but it is an explanation of how a God may actually exist.

    • KevinC

      Despite the title of this article “A Skeptical Look”, I think you’re a bit overly optimistic about the possibility of intelligent life on other planets. The list of requirements for life keeps growing. A large moon being just one of them.

      • Doc Bill

        Life as we know it, you mean. Nobody knows what the “list of requirements” is, or even if there is such a list.

        • KevinC

          Agreed. Certainly there isn’t a list per se but there are also some non-negotiables that even planet hunters agree are absolutely necessary for identifying habitable planets. First, all life is carbon-based. As such, the planet must be able to maintain a certain narrow range of temperature over billions of years. That requires extremely low eccentricity in its orbit around a G-type star. The number of astronomical and terrestrial characteristics necessary for such a planet are many.

          Aside from temperature, the surface gravity of a planet must be within a certain range or else it would either lose its atmosphere or retain too much volatiles. And lastly, a moon is essential for stabilizing the planet’s obliquity and allowing for slight but varying climates.

          When one factors in all of the variables, the number 700 quintillion isn’t that impressive.

          • Doc Bill

            Once again, “life as we know it.”

            Pop quiz: name an organism that doesn’t eat anything? Geobacter. They process electrons directly from the soil.

            There are no “non-negotiables” as far as I can tell. Even if you want to limit your search to lovely, quiet planets like the Earth then you would have to ignore the eras when the atmosphere was reducing – methane, nitrogen and carbon dioxide – and THAT would be your starting point, rather than where we are today. And don’t forget the very unpleasant Snowball Earth.

            In discussing evolution and life in the universe, Richard Dawkins said that he had no idea what chemical processes would develop on an alien world, but the diversity of life would be Darwinian. By that he meant in the general sense of a way of randomizing and passing on genetic information.

            Well, until we actually investigate another planet or discover a “universality” of the process of evolution I’m not ready to accept Dawkins’ pronouncement.

            Practically, unless a form of life developed on one of Jupiter’s or Saturn’s moons, we’ll probably never know the answer just because of the travel time to another world.

    • KevinC

      I’m not sure what your point is by bringing up geobacter. There are many exotic extremophiles but they’re all carbon-based with relatively limited conditions for viability. I suppose if you don’t want to admit to any non-negotiables, then you could say there are 75 billion habitable planets in our galaxy. But that would be an empty statement.

      It seems we’re arguing from two different points of view. You’re speaking from a biological and climatological view, while I have in mind astronomical and geological criteria. You can’t have the former until the latter is met.

      • SmilodonsRetreat

        Name an astronomical or geological criteria that is absolutely required for any form of life to exist.

        • KevinC

          That’s easy. Liquid water

          But to have that requires stellar radiation and/or geothermal heat. These are necessary for long-term, liquid surface water. To maintain stellar radiation, a planetary body must be orbiting a G-type star. The other 96% of stars are either too short-lived, too cool/not massive enough or in binary systems. To generate geothermal heat and retain liquid water with its magnetosphere, the planet’s core must have enough radioisotopes and iron.

          Since there is no evidence of intelligent life elsewhere in the universe, I’ll continue in the height of arrogance believing there is no other life in the universe while you continue in the depths of humility believing you’re nothing but a bag of molecules.

          • SmilodonsRetreat

            So there is no possible way that any form of life could ever evolve in liquid methane? Or liquid hydrocarbons? Or anything else… ever.

            Not “life as we know it”, but any form of life.

            • KevinC

              Now this is a curious phrase: “Not ‘life as we know it’, but any form of life.” By “any form of life” do you mean life of which we know nothing because it hasn’t been discovered yet and exists only in the imaginations of those like Gene Rodenberry and George Lucas?

            • SmilodonsRetreat

              No. I mean life based on ketones. Life based on liquid methane. Life based on silicon/boron.

              We could get into a huge discussion on what “life” even is. But that’s another article.

          • Doc Bill

            Oh, here we go, KevinC! You’re just a crank. Typical know-nothing with a severe case of Dunning-Kruger. Tell you what, buddy boy, how about spending 30 years or so studying chemistry then come back here and try again.

            Liquid water is a requirement for life? Why?

            G-type star? Other than Star Trek which had it’s M-class planets, why?

            Oh, just pulled it out of your ass. Well, that makes sense.

            Hey, how am I doing on civility? Crossed the line yet? I love how you delicate little snowflakes are so hung up about tone and civility. You wouldn’t last a week in grad school.

            So, since I have seen no evidence that you have a freaking clue what you’re talking about and are unable to conduct an intelligent discussion, this bag of molecules I call me, myself and I will continue in the height of arrogance bolstered by decades of work as an actual scientist with the knowledge that, so far, no life has been discovered outside of our planet, but that nothing in the realm of physics and chemistry prevents nor precludes the existence of energy-processing, self-sustaining, cyclic chemical reactions elsewhere in the Universe, provisionally noting that an alien life might not be based on either self-sustaining or cyclic chemical reactions, to hold the position that there is no known list of requirements for what we call life.

            I would further submit based on my vast knowledge (the size of a small planet) on this subject that it may be damned difficult to detect an alien life form as living (in our sense of the world) and probably impossible to detect what we would call “intelligent” life, and damned teeny, tiny, Impossible with a capital “I” to communicate with it, much as Spock and I would find that fascinating.

            • KevinC

              Hi DocBill, thank you for your response. So your background is in chemistry. That would explain your fixation with it. I guess when all you’ve got is a hammer, everything looks like a nail.

              In the short time I’ve been here, I haven’t complained about the tone or civility. You must have me confused with someone else. So by all means unleash yourself – limited only by the moderator – and see if I’ll wither under your mighty wrath.
              Hint: not likely friend

              “Liquid water is a requirement for life? Why?”

              “G-type star? Other than Star Trek which had it’s M-class planets, why?”

              Because less massive, cooler red dwarfs would require a habitable zone, and therefore an orbit, closer to the host star inducing strong tidal forces on the planet. These tidal forces would brake its rotation and the planet would end up like our moon in synchronous rotation around its star. Venus and Mercury are well on their way to tidal locking. Of course, being closer to the star puts the planet at higher risk of exposure to solar flares increasing the X-ray radiation many times that of the sun.

              I’m merely expressing my skepticism that there is life elsewhere in the universe and the reasons I think it’s unlikely to be found other than here on earth. This is a skeptics’ website, is it not? You accuse me of pulling things out of my arse when you are suggesting life without water, probably silicon-based life and all kinds of other life forms that exist only in your Star Trek fantasies yet declaring it will be impossible to detect or even communicate with said intelligent life. Who’s arse is being evacuated?

            • SmilodonsRetreat

              Your link contains zero peer-reviewed papers. The number 3 link is to Lance Armstrong’s “LiveStrong” website. And you think that’s a valid response?

              What does water do for life? It’s a medium. Some things dissolve in it very well and some things don’t.

              In other words, any polar molecule that is liquid a particular temperature will fulfill that requirement. There is nothing in your links that suggest that liquid hydrocarbons, methane, ketones, or anything else could work.

              As far as your statement, as I showed in my article, the stuff needed for life as we know it is ubiquitous in the universe. It’s nearly trivial to make. And there are so many planets, you don’t think that one could have life, as we know it (i.e. water based) on it?

              I’d be willing to bet real money that we will find life in at least one other place in our solar system, probably two. But that’s just based on understanding the chemistry behind life and the locations in the solar system where similar conditions exist.

            • KevinC

              “life as we know it” has been used a half dozen times in this thread by the two of you. The influence of Star Trek on the psyche of a generation has been quite profound.

              With all due respect gentlemen, “life as we know it” are weasel words. And as Homer Simpson reminds us, “Weaseling out of things is what separates us from the animals – except the weasel.” There is no evidence, just speculation, for “life as we don’t know it” so let’s stick to reality. You’re more than welcome to continue to believe in other forms of life but it has no place in a discussion of what’s required for carbon-based life elsewhere in the universe.

              “Your link contains zero peer-reviewed papers. The number 3 link is to Lance Armstrong’s “LiveStrong” website. And you think that’s a valid response?”
              The Google search was an attempt at humor. I thought it was pretty funny. I remember the first time I was introduced to lmgtfy.com; I LMAO. Of course, I don’t have control over what Google returns for a search so if “LiveStrong” comes up in the results, well, what can I say. As for peer-reviewed papers, one detailing the discovery of non-carbon-based life would be most appreciated. If there are none, my Google search is quite valid.

              “What does water do for life? It’s a medium. Some things dissolve in it very well and some things don’t.”
              As DocBill says it is a “universal solvent” for a great many things and luckily hydrocarbons isn’t one of them. Otherwise there would be no cell membranes. So yeah, let’s be glad for that.

              “I’d be willing to bet real money that we will find life in at least one other place in our solar system, probably two.”
              I’m skeptical 🙂

            • Doc Bill

              KevinC, you really are as thick as two short planks.

              We have one data point: this planet. Life as we know refers to that one data point.

              There is nothing, no list, no physical constraint that limits another form of chemical life existing on another planet.

              So the reality, my dense, obtuse, little twerp, is that the chemistry that would result in life on another planet is not dependent on the conditions that life appeared on this planet. You keep returning to Earth. Haven’t you seen Frozen? Let it go, let it go!

              Furthermore, consider that there is a lot more water on Europa than there is here. I’ll wager 10,000 quatloos that we find alien life there.

              p.s. Star Trek to my knowledge only once ventured outside of the bipeds they could hire as actors with the Horta. “Damn it, Jim, I’m a doctor not a bricklayer!” Even so, the Horta was still terrestrial regarding its psychology. Not surprising since it was a TV show written by people, not Horta.

            • KevinC

              Hi DocBill, thank you for your response. No need to bet 10,000 quatloos. By the time you lose the bet, you’ll be long dead and incinerated.

              Any progress on finding an alternative to water for your imaginary life forms on the gazillions of planets out there? Here’s a hint: the molecule should be small and abundant and therefore easy to identify. While I’m waiting, I’ll show why life on Europa is yet another balloon destined to burst for the advocates of their precious Copernican Principle.

              Working under the naive assumption that water = life, you were kind enough to admit that “there is a lot more water on Europa than there is here.” Since Europa is about the same size as our moon, that would make Europa’s ocean about 100 kilometers deep. Whatever liquid water exists on that moon results from its only energy source, tidal energy, coming from the moon’s interior. There are two scenarios that I see. 1) Any life that manages to eke out an existence will be limited to the ocean floor near thermal vents where pressures are immense. Ergo it will be extremely difficult to prove that there is life on Europa. 2) If the ocean were mostly liquid at times, minerals and nutrients would be so diluted as to be ineffectual to maintain a biosphere.

              In addition to that, Europa also suffers from the drawbacks that I’ve already discussed with planets near M-type stars: synchronous rotation with Jupiter and true polar wander (80 degrees) because it lacks its own satellite. Thus proving my point that that is the fate of most planets orbiting the majority of stars in our galaxy.

              And worst of all, in addition to the above, Europa’s ocean is probably a global Dead Sea. Since its tidal heating is episodic due to orbital resonance, the ocean may freeze over nearly completely. During the freezing episodes, since salt isn’t incorporated into ice when it freezes (as a chemist you should know this), the ocean’s salinity would spike to intolerable levels for any life to survive (real life not the imaginary kind).

              It seems that I’m the only one making a scientific case for life out there (or the lack thereof) while all you two offer are big numbers and “life as we know it”.

            • SmilodonsRetreat

              If those assumptions “prove” your point, then there’s no point in even discussing this further. Science isn’t ONLY about evidence. It’s about looking at situations in a different way and then determining if that different way is valid… with evidence. Had you been a scientist, humans would probably still think only lightening could create fire.

              As far as other chemicals, I’ve mentioned several. I note that you failed to admit that. Do they have life associated with them? Of course not. However, the chemical properties are similar and you’re still talking about life as we know it. Of course, if you define life only as “life as it exists on Earth”, then you automatically exclude every other planet in the universe.

            • Doc Bill

              And artificial (Xeno) nucleic acids have been synthesized, inserted into bacterial DNA and they replicate just fine. Thus, life as we don’t know it could be and probably is quite different from life as we know it. A recent paper explored the thermodynamic constraints of a planet with a hydrogen sulfide/ammonia ocean with favorable results. So, once again and for the kazillionth time, nothing in chemistry precludes life as we don’t know it, nor limits life as only how we know it. Game, set and match.

            • KevinC

              “Thus, life as we don’t know it could be and probably is quite different from life as we know it.”
              That actually made me laugh, my friend.

              You draw the conclusion that life as we don’t know it is “quite different” because Xeno nucleic acids with hydrogen bonds have been inserted into ALREADY EXISTING, CARBON-BASED LIFE and they replicate. WOOOOW!!!!! That’s like replacing an old SATA hard drive with an SSD and concluding you’ve created a new computer. Ridiculous. It is conclusions such as these that probably led Mark Twain to comment “There is something fascinating about science. One gets such wholesale returns of conjecture out of such a trifling investment of fact.”

              Care to provide that recent paper and what do you mean by favorable results?

              “Game, set and match.” Not so fast.

            • Doc Bill

              Look it up yourself, nitwit. Actually, don’t bother. You wouldn’t understand the abstract much less the rest of the paper.

            • KevinC

              “Look it up yourself”
              Exactly the response I was expecting. Instead of linking to the paper in the first place, you provide some nebulous, pie-in-the-sky description thinking I’ll take your word for it. You’re not showing much confidence in the paper if all you can offer is a promise of “favorable results”. No link? No problem. You haven’t made a very good case for your side up to this point. Why start now?

            • SmilodonsRetreat

              Your posts are being sent to spam in Disqus.

            • Doc Bill

              Too bad, really, but predictable. Like most creationist trolls, Kev-C is a science poser, tossing around sciency-sounding terms without any comprehension. “Applying the laws of chemistry” really made me laugh! Sadly, all the knowledge in the universe is now at their fingertips, but they want no part of it. Too spooky scary for them, I guess.

              In all my years of dealing with creationist trolls and science deniers and those afflicted with DK, I have only experienced ONE (1), a single individual who pierced the veil and said, “OMG, all this stuff I’ve been told is wrong!” It was a young lady who still lurks around the Panda’s Thumb from time to time.

              It had to do with Noah’s Flood calculations using simple geometry and some approximations using a formula to calculate how much water it would take to cover a planet to any depth you wanted. The Ah Ha! moment came when she realized no matter the depth there was never enough water. We did some other fun calculations and pointed her to Thunderf00t’s channel for his analysis of the thermodynamics of “flood theory.” Good stuff.

            • KevinC

              Hi DocBill, thank you for your response. Glad I made you laugh. Being a one trick pony with regard to chemistry, you’re probably pretty comfortable talking about the biochemistry of life. Your chemistry background is in the life sciences, right?

              Your response is rather lengthy when all you had to do is provide a link to the paper you referenced so I’ll no longer think that you’re bluffing about the paper or your scientific background.

            • Doc Bill

              Laughing at you, troll!

            • SmilodonsRetreat

              Here, it took four seconds to cut and paste Bill’s statement into google.


            • KevinC

              Hey, you’re right! It took about 4 seconds. Unfortunately we’ve moved beyond nucleic acids and are now discussing “the thermodynamic constraints of a planet with a hydrogen sulfide/ammonia ocean with favorable results“.

            • SmilodonsRetreat

              Yeah, well… now YOU KNOW WHAT TO GOOGLE

              You have to want to learn this stuff. It appears that you are not interested and are willing to die on this hill. That’s fine. I couldn’t care less.

              But when you come to a blog about science, then you better expect to know science. If you want to talk about non-Earth biochemistries, then you probably ought to read the relevant research BEFORE trying to argue it.

            • KevinC

              Not sure what happened to my last comment but let’s try this again.

              DocBill, yours is exactly the response I expected to receive. If you were confident enough in the paper’s science, you would have provided the link in the first place. The fact that you didn’t tells me all I need to know about your vague and questionable assessment of the “recent paper”.

            • KevinC

              Your response is rather confused and incoherent. Each sentence has me wondering what exactly your point is.

              “If those assumptions ‘prove’ your point, then there’s no point in even discussing this further.”
              Synchronous rotation and true polar wander are not assumptions but facts. And why those facts would preclude further discussion is beyond me.

              “Science isn’t ONLY about evidence. It’s about looking at situations in a different way and then determining if that different way is valid… with evidence.”
              Agreed. But scientific evidence is filtered through human bias, prejudice and pet philosophies yet many times with objectivity as I’ve done so far. Claiming there are no constraints, no lists, no limits and only possibilities is NOT evidence.

              “Had you been a scientist, humans would probably still think only lightening could create fire.”
              Non-sequitur. Humans had mastered fire many millenia before I was born.

              “As far as other chemicals, I’ve mentioned several. I note that you failed to admit that.”
              Admit that you mentioned other chemicals? I admit it.

              “Do they have life associated with them? Of course not.”
              Then why bring them up?

              “However, the chemical properties are similar”
              So. Many liquids freeze, flow and vaporize but still don’t come close to water as substitutes for life.

              “you’re still talking about life as we know it”
              Until I see evidence otherwise.

              “Of course, if you define life only as ‘life as it exists on Earth’, then you automatically exclude every other planet in the universe.”
              Of course it’s tough to prove a universal negative but you said yourself “looking at situations in a different way and then determining if that different way is valid… with evidence”. That’s what I’ve been doing by applying the laws of physics, chemistry and biology (especially wrt OoL research) and I come up with no life other than here on Earth. Create life in the lab and I’ll change my mind.

            • SmilodonsRetreat

              Fact is, life is likely possible with other biochemistries.

              We’ll not know for sure until we find it. When we do, which is, again, more likely than not, we’ll have a second example to think about. It’s not going to be Star Trek, with humanoids or anything else. It’s likely to be something that will cause to rewrite all the books.

              As far as your comments, you have zero evidence that anything you’ve said on the subject is true. You cannot justify ONLY water, for example. When you have evidence that says, life can only exist with water, amino acids, and DNA, then you might have a point. But, that claim doesn’t match the evidence.

            • Doc Bill

              “Create life in the lab and I’ll change my mind.” No you won’t. That’s a lie all creationists tell. The old Show Me Gambit. Meh, you’ll just change the subject, move the goalposts, ignore it, ad nausea.

              However, thanks for the evidence, Kev-0, that you’re just another ignorant troll suffering from DK. I hope your delusional world is filled with unicorns and jelly beans.

            • Doc Bill

              So, KevinC, you failed to ask the proper question to poor old Google. The proper question is: Why is water essential to life as we know it on planet Earth? The answer is only partially because it is a “universal solvent,” but I’ll leave that as an exercise for you to flesh out if you so desire.

              My observation still stands that our definition of life (which used to be so simple) will probably change when we encounter alien life just as Geobacter changed our view of classical respiration.

              My observation still stands that self-sustaining chemical reactions do not require earth-like compositions. I didn’t mention silicon specifically because it has other problems, but, sure it could be involved in life components just as it is here.

              Your observation about the kind of star-planet relationship, AGAIN, is limited to your provincial view that life has to be elsewhere as it is here.

              So, yes, as a chemist everything looks like chemicals and, lo and behold, that’s exactly the way it is.

              As for communication with sentient aliens, we haven’t done very well with life on our own planet, I doubt we’d have a snowball’s chance in hell with a totally alien form. On our own planet consciousness is a spectrum and we’ve only in the past decade or so started to understand how it operates across species that at least have some common frames of reference: common evolution, common evolution of psychology and living on the same planet. A difficult problem made worse by removing those commonalities.

              Tell me, oh great KevinC, what’s my cat dreaming about? Chasing or getting chased?

            • KevinC

              “I’ll leave that as an exercise for you to flesh out if you so desire.”

              Properties of water necessary for life
              -Density decreases to the freezing point
              -The latent heat of freezing water is one of the highest of all known fluids
              -The latent heat of evaporating water is highest of any known fluid
              -The thermal capacity is higher than most other fluids
              -The thermal conductivity of water is four times greater than any other common liquid
              -Yet the thermal conductivities of ice and snow are low

              Surface tension is very high compared to most liquids

              One of the lowest viscosities of fluids
              -allows for a circulatory system with conduits as small as 3 to 5 microns
              -Allows blood to be a shear thinning, non-Newtonian fluid

              There are other characteristics important at both the biological and global levels and everything in between. But it’s your turn to flesh out why the above are so important to life and suggest another liquid medium to replace it.