4 ms·

To be cynical, a lot of things are possible. It's possible that anaerobic bacteria still live in small pockets beneath the surface of Mars. It's possible, if un

by Charos 13y ago

To be cynical, a lot of things are possible. It's possible that anaerobic bacteria still live in small pockets beneath the surface of Mars. It's possible, if unlikely, that extremophiles survive on the sweltering surface of Venus, or floating in its sulphurous clouds. Of course, the fact that these things are possible is still incredibly cool. While this article lacks much technical substance, this is the kind of thinking that gave us Cosmos and Pale Blue Dot. I hope enough people retain this author's sense of scientific curiosity and excitement for discovery. While cold logic, expected-value calculations, and cynicism are important in a research setting, outside of the lab it's important for people to be able to get excited about little (or big!) things like this. We can have scientific progress and childish glee coexist. Thank you for posting this.

jerf 13y ago
Floating in the clouds of Venus, sure. There's some semi-Earthlike zones in the cloud layer. On the surface, very probably not. It is unlikely that there is any structure that could pump entropy out of the cell faster than the horrific surface environment of Venus would be pumping it in. (More conventionally known as heat, but I find this formulation helps focus on the fact that "too hot" really is an intrinsic problem for life, not merely an incidental one that might be overcome by more chemistry.) I'm not even 100% convinced that a technological solution is possible that could work over geologic time frames, let alone adding the restrictions of abiogenesis on to the structure. (Though on the topic of abiogenesis, it's difficult to see how to apply any of the current thoughts on that to an atmospheric environment; Venusian extremophiles would also probably be immigrants from Earth.)
- unclebucknasty 13y ago
  It has always intrigued me that we consider the possibility of other life forms in a manner that is largely relative to our understanding of life on earth and, hence, biology. But, even our understanding of DNA need not be applicable to other life forms. I don't see why there has to be any real limitation on conditions or otherwise. As the article mentions, we have been surprised to find extremophiles near thermal vents right here on Earth (which reach temperatures roughly equivalent to the Venusian surface). There we find, for instance, bacteria that rely upon hydrogen sulfide vs sunlight for energy. This is what we consider a "harsh" environment of chemicals, heat, pressure, etc. However, when we attempt to remove organisms from that environment to study them, they usually die pretty quickly. In other words, ours is the harsh environment as far as they are concerned. Elsewhere, we have found organisms whose DNA was thought to be composed of arsenic vs phosphorous. While this was ultimately refuted, for a period we once again thought we'd discovered something that, in an instant, completely changed our understanding of life. So, I guess my point is that we assume life must conform to certain requirements and/or conditions until we find life forms that violate our assumptions. Given a Universe as vast and diverse as our own, I sincerely believe that anything is possible and perhaps even likely.
  - jerf 13y ago
    Information theory is a fundamental constraint on any halfway sensible theory of life. If you can't pump out entropy faster than it comes in, you will, by definition, be randomized, which pretty much by definition is not alive. I know people think they're being sophisticated when they insist no limits can be placed on the form of life, but it's not true; it's naive. There are in fact certain very powerful and generic limits that can be placed on life with some powerful mathematics, such as the one I mentioned. It's fun to imagine a life form in science fiction that lives on the surface of the sun, but in reality they are not possible; there's no way they could retain any interesting structure in such a high entropy environment. To argue otherwise is basically to be arguing against thermodynamics. This basically puts this position firmly on the "crank" side, not the scientifically knowledgeable one. Also, the idea that there are no limits on what life can look like is observationally false. The vast majority of places we look, we do not see life. Even if we manage to find a few simple life forms in a few of the slightly less hostile places in the solar system, it still won't change that fact; life is observationally not abundant everywhere, regardless of conditions. There definitely is a difference between conditions conducive to life and those not. Even what we call "extremophiles" are only surprising in purely local terms; in absolute terms in the Solar System, volcanic vents are still incredibly hospitable places compared to what is out there. In its own way, trying to argue from extremophiles to the general case is its own perversively parochial argument; the idea that extremophiles are actually "extreme" is a very terra-centric viewpoint.
    - unclebucknasty 13y ago
      Wow. >"If you can't pump out entropy faster than it comes in, you will, by definition, be randomized, which pretty much by definition is not alive You're essentially just saying "if you can't stay alive, then you're dead". It's a non-statement. My point was that's a big if. There are environments in which we wouldn't have thought it possible, until it was proven otherwise. "I know people think they're being sophisticated when they insist no limits can be placed on the form of life, but it's not true; it's naive" I don't think it particularly sophisticated to hold this view. I think it simply acknowledges the limitations of our knowledge (limitations which have been proven time and again). As a result, "naive" is actually the word I'd use to describe those who believe that their prior observations represent the full set of possibilities. The world was once flat and all of that. So, ironically, I would say that your entire argument is based on a profound naivete. It is limited to what we currently understand/have observed and it assumes that it is foolish to consider otherwise. >the idea that there are no limits on what life can look like is observationally false. The vast majority of places we look, we do not see life... What does that mean? I don't think that anyone's asserting that life must exist in every single place we look; rather simply that some form of life could exist in virtually every single place we look, because we truly do not know what the bounds are. And, at a minimum, it almost certainly exists in places that we don't expect. The more general point is that it's extraordinarily presumptive to conclude that we know definitively what life could be, based simply on our own observations to date. >the idea that extremophiles are actually "extreme" is a very terra-centric viewpoint. Well, exactly. That's my point. We've dubbed them "extremophiles" because of our own limited reference point at a particular place in time. Their existence is simply evidence of our limited observational knowledge in the past. Ironically, enough, that's a term that is still generally accepted because even in spite of them showing us that we were wrong about life at some point, we still can't quite wrap our minds around the fact that we were wrong. Now, you are simply arguing from a slightly evolved set of observational knowledge that happens to accommodate the existence of those "extremophiles". But, you're simply saying "OK, we might have been wrong once. But, we can't be wrong again". It's really an odd argument to make. And you're adding that volcanic vents aren't such a bad place to live after all. Well, yeah. Because we now know that life exists there. You can follow that line of reasoning until we find life at the center of the Sun.

by Charos 13y ago

jerf 13y ago

Floating in the clouds of Venus, sure. There's some semi-Earthlike zones in the cloud layer. On the surface, very probably not. It is unlikely that there is any structure that could pump entropy out of the cell faster than the horrific surface environment of Venus would be pumping it in. (More conventionally known as heat, but I find this formulation helps focus on the fact that "too hot" really is an intrinsic problem for life, not merely an incidental one that might be overcome by more chemistry.) I'm not even 100% convinced that a technological solution is possible that could work over geologic time frames, let alone adding the restrictions of abiogenesis on to the structure. (Though on the topic of abiogenesis, it's difficult to see how to apply any of the current thoughts on that to an atmospheric environment; Venusian extremophiles would also probably be immigrants from Earth.)

unclebucknasty 13y ago
It has always intrigued me that we consider the possibility of other life forms in a manner that is largely relative to our understanding of life on earth and, hence, biology. But, even our understanding of DNA need not be applicable to other life forms. I don't see why there has to be any real limitation on conditions or otherwise. As the article mentions, we have been surprised to find extremophiles near thermal vents right here on Earth (which reach temperatures roughly equivalent to the Venusian surface). There we find, for instance, bacteria that rely upon hydrogen sulfide vs sunlight for energy. This is what we consider a "harsh" environment of chemicals, heat, pressure, etc. However, when we attempt to remove organisms from that environment to study them, they usually die pretty quickly. In other words, ours is the harsh environment as far as they are concerned. Elsewhere, we have found organisms whose DNA was thought to be composed of arsenic vs phosphorous. While this was ultimately refuted, for a period we once again thought we'd discovered something that, in an instant, completely changed our understanding of life. So, I guess my point is that we assume life must conform to certain requirements and/or conditions until we find life forms that violate our assumptions. Given a Universe as vast and diverse as our own, I sincerely believe that anything is possible and perhaps even likely.
- jerf 13y ago
  Information theory is a fundamental constraint on any halfway sensible theory of life. If you can't pump out entropy faster than it comes in, you will, by definition, be randomized, which pretty much by definition is not alive. I know people think they're being sophisticated when they insist no limits can be placed on the form of life, but it's not true; it's naive. There are in fact certain very powerful and generic limits that can be placed on life with some powerful mathematics, such as the one I mentioned. It's fun to imagine a life form in science fiction that lives on the surface of the sun, but in reality they are not possible; there's no way they could retain any interesting structure in such a high entropy environment. To argue otherwise is basically to be arguing against thermodynamics. This basically puts this position firmly on the "crank" side, not the scientifically knowledgeable one. Also, the idea that there are no limits on what life can look like is observationally false. The vast majority of places we look, we do not see life. Even if we manage to find a few simple life forms in a few of the slightly less hostile places in the solar system, it still won't change that fact; life is observationally not abundant everywhere, regardless of conditions. There definitely is a difference between conditions conducive to life and those not. Even what we call "extremophiles" are only surprising in purely local terms; in absolute terms in the Solar System, volcanic vents are still incredibly hospitable places compared to what is out there. In its own way, trying to argue from extremophiles to the general case is its own perversively parochial argument; the idea that extremophiles are actually "extreme" is a very terra-centric viewpoint.
  - unclebucknasty 13y ago
    Wow. >"If you can't pump out entropy faster than it comes in, you will, by definition, be randomized, which pretty much by definition is not alive You're essentially just saying "if you can't stay alive, then you're dead". It's a non-statement. My point was that's a big if. There are environments in which we wouldn't have thought it possible, until it was proven otherwise. "I know people think they're being sophisticated when they insist no limits can be placed on the form of life, but it's not true; it's naive" I don't think it particularly sophisticated to hold this view. I think it simply acknowledges the limitations of our knowledge (limitations which have been proven time and again). As a result, "naive" is actually the word I'd use to describe those who believe that their prior observations represent the full set of possibilities. The world was once flat and all of that. So, ironically, I would say that your entire argument is based on a profound naivete. It is limited to what we currently understand/have observed and it assumes that it is foolish to consider otherwise. >the idea that there are no limits on what life can look like is observationally false. The vast majority of places we look, we do not see life... What does that mean? I don't think that anyone's asserting that life must exist in every single place we look; rather simply that some form of life could exist in virtually every single place we look, because we truly do not know what the bounds are. And, at a minimum, it almost certainly exists in places that we don't expect. The more general point is that it's extraordinarily presumptive to conclude that we know definitively what life could be, based simply on our own observations to date. >the idea that extremophiles are actually "extreme" is a very terra-centric viewpoint. Well, exactly. That's my point. We've dubbed them "extremophiles" because of our own limited reference point at a particular place in time. Their existence is simply evidence of our limited observational knowledge in the past. Ironically, enough, that's a term that is still generally accepted because even in spite of them showing us that we were wrong about life at some point, we still can't quite wrap our minds around the fact that we were wrong. Now, you are simply arguing from a slightly evolved set of observational knowledge that happens to accommodate the existence of those "extremophiles". But, you're simply saying "OK, we might have been wrong once. But, we can't be wrong again". It's really an odd argument to make. And you're adding that volcanic vents aren't such a bad place to live after all. Well, yeah. Because we now know that life exists there. You can follow that line of reasoning until we find life at the center of the Sun.