5 ms·

SETI's hard steps and how to resolve them

50 points by JPLeRouzic 2y ago

echelon 2y ago
Here's a parameter I don't think the Fermi Equation takes into account: I call it "Fragile Universe", based off of the notion of the "Fragile" or "Vulnerable World Hypothesis" [1]. f_c is the parameter for the fraction of "civilizations that reach the technological level whereby detectable signals may be dispatched", so that handles the "Fragile World Hypothesis". Alien civilizations can wipe themselves out, exhaust resources, etc. before we get to see their detectable signals [2]. What the equation doesn't take into consideration is the possibility that an advanced species can trigger the destruction or total reset of the entire universe, eg. by nucleating the vacuum collapse. The first advanced species to reach that point could kill every species in the universe and start the whole thing over from scratch. This is an extreme version of the anthropic principle [3]. We exist because the universe hasn't been reset yet. By us or otherwise. Presumably we might be the first to get there. Universe fragility could be the reason we don't see aliens. We could be the very first, and we could wind up hitting the reset button. [1] https://nickbostrom.com/papers/vulnerable.pdf https://nickbostrom.com/papers/vulnerable.pdf ; tldr: advanced species can trivially wipe themselves out and will tend to do so. Not just nukes, but in the extreme, your average citizen can create grey goo at home with the press of a button that will turn the entire planet into paper clips. [2] It could be that the time frames in which advanced civilizations emit detectable signals are so geologically small as they shift into non-detectable modes (eg. dark forest, disinterest in expansion, shift into a higher plane of existence, etc.), but that's orthogonal to the discussion. [3] https://en.wikipedia.org/wiki/Anthropic_principle https://en.wikipedia.org/wiki/Anthropic_principle
- ziddoap 2y ago
  >eg. by nucleating the vacuum collapse. The first advanced species to reach that point could kill every species in the universe and start the whole thing over from scratch. How do you imagine the Universe resetting? Assuming the false vacuum decay occurs, I don't think any species (no matter how advanced) could reset the vacuum state back to a metastable state post-collapse. It does just appear to be the anthropic principle, but with some extra steps.
  - echelon 2y ago
    Maybe it doesn't? Maybe there are lots of other universes, and we just happen to be in one of the metastable ones that hasn't collapsed yet.
- jebarker 2y ago
  Novice question here: What use is there in adding a term like that to the Drake equation? It seems like it's value would be completely uncertain (like other terms in the equation) and so you have overwhelming uncertainty in the output of the equation.
  - andrewflnr 2y ago
    Your instinct is largely correct. This is a silly idea.
  - simne 2y ago
    Right answer is - we don't know. Unfortunately, Drake equation now is just estimate, without any real data, as humanity just don't know example of any extraterrestrial life at all. And what even more sad, our empty knowledge is not because non-existence of life in Universe, but because our science is very young and we just don't have powerful enough instruments to detect et life. We could only be sure, life was not exist on Moon equatorial stripe on surface, but for example we cannot be sure about deep under-surface and about polar regions.
    - simne 2y ago
      Things are even worse for intelligent life. Because we only could understand et with similar to our level of sci/tech development, but what if we encounter civilization, even one magnitude older than our? For example, now our science have evidences about human civilizations up to somewhere 10k..50k years, and our current civilization oldest evidences are about 5k years. Imagine, how could look our civilization in 500k years? And if we use adequate considerations, human life was appear on Earth ~ 500 thousands years ago, and before was possible reptile civilization, for about 10 millions years, but our Earth become life planet ~ billion years, and exist planets in other star systems, which are tens billions years older than Earth. So what I mean, in our 5k years our civilization decided to re-circling resources and probably in ~ 100 years we could implement this decision and will become invisible to ets of our level. Imagine, what technologies would be available for magnitude older civilization. Could someone be sure about possibility of detection so much newer technologies? You may hear classification of seti scientists as Cygnus, Cancer and Pike. What I want to say, civilizations younger than our are detectable for us, but older are detectable only if them decided to contact us.
- bluGill 2y ago
  The universe is 93 billion light years across. No alien can reset it within time spans that matter to our solar system which has maybe 8 billion years left before our sun dies)
- wat10000 2y ago
  I don't think that solves it. The Fermi paradox is that based on the probabilities we estimate, we should see lots of aliens, and we don't. Thus something in our estimates must be wrong, but we don't know what. This fragility idea just shifts it from "we should see lots of aliens and we don't" to "the universe should have been destroyed by now and it hasn't been."
  - DennisP 2y ago
    Actually the Drake equation may not say that: > When we take account of realistic uncertainty, replacing point estimates by probability distributions that reflect current scientific understanding, we find no reason to be highly confident that the galaxy (or observable universe) contains other civilizations, and thus no longer find our observations in conflict with our prior probabilities....When we update this prior in light of the Fermi observation, we find a substantial probability that we are alone in our galaxy, and perhaps even in our observable universe (53%–99.6% and 39%–85% respectively). ’ https://arxiv.org/abs/1806.02404 https://arxiv.org/abs/1806.02404
AnotherGoodName 2y ago
The steps don't have to be that hard for us to be unique. There are 10^22 to 10^24 stars in the Universe (a big range of uncertainty there but it doesn't matter for this point). That sounds like a lot but anyone with knowledge of combinatronics would immediately say holy shit that's a small number. Cryptography buffs are probably looking at that going "that can't be right, it's a tiny number", you divide it by 10 repeatedly, 24 times in fact and you're down to nothing. 24 not-at-all 'hard' steps and we're probably alone. You've probably heard "there's soooo many stars in the universe there has to be other life out there". There really isn't that many in terms of probability.
- A_D_E_P_T 2y ago
  This is too facile. The Copernican principle assumes that we are not in a spatially or temporally privileged position, and there are no obvious hard steps -- to say nothing of 24. It's frankly bizarre to go from there to "we are unique among 10^22 stars."
  - AnotherGoodName 2y ago
    Having thoughts around how many stars are in the observable universe is a very reasonable starting point. Even without a privileged position the observable universe is still well defined in an expanding universe - at some boundary other stars are moving away too fast to be observed. So we can absolutely state this.
  - DennisP 2y ago
    In this case the Copernican principle is at odds with the anthropic principle. If there were only one place in the universe with intelligent life, then necessarily that's where we would be. GP may be thinking of this paper, which uses a reasonable probability distribution for each parameter in the Drake equation, and finds a decent chance that there is no other technological civilization in the observable universe: https://arxiv.org/abs/1806.02404 https://arxiv.org/abs/1806.02404
    - jovial_cavalier 2y ago
A_D_E_P_T 2y ago
On timescales of billions of years, we don't know if any of those steps are "hard," "easy," or "inevitable." As the first commenter to that article notes at the link, we have only a single datapoint. It's certainly unclear that photosynthesis is an ironclad requirement for life, and, in any case, it evolved multiple times in parallel on Earth. (Anoxygenic photosynthesis in fact evolved, de novo, more than once.) I'd add that it's also by no means a given that life, broadly defined, can only evolve around a sunlike star. Speculation around "hard steps" is pseud naval gazing until we gather more datapoints. It's not even valuable as speculation -- except perhaps as an exercise in countering sloppy thinking.
- bluGill 2y ago
  > I'd add that it's also by no means a given that life, broadly defined, can only evolve around a sunlike star. Not a given, but not unreasonable either. Larger stars die faster so they probably won't be around long enough for life. Smaller stars last longer, but they also emit less energy and so there is less likely to be higher life forms just because there isn't enough energy to support life. Of course life might not be like we know it, but carbon and water are very common in the universe compared to most of the other options and so they are more likely.
  - jdhwosnhw 2y ago
    > Smaller stars last longer, but they also emit less energy and so there is less likely to be higher life forms just because there isn't enough energy to support life. This isn’t really true. The energy density at a planet’s surface is a function of both the star’s luminosity and the planet’s distance. Most star’s (at least in the Milky Way) are small, and most stars have planets in orbits closer than is Earth’s. The so called “Goldilocks zone” is expected to have at least one planet in it for a very large number of stars (again, at least in our galaxy).
    - Teever 2y ago
      > most stars have planets in orbits closer than is Earth’s. I don't think that this is true. IIRC it's an artifact of the techniques we use to detect extrasolar planets -- our techniques are biased to detect planets that are closer to their stars than further away,
perihelions 2y ago
- "The fact that it did happen here tells us nothing more than that, and until we dig out evidence of a ‘second genesis,’ perhaps here in our own Solar System inside an icy moon, or on Mars, we can form no firm conclusions." I'm convinced the absence of evidence is, itself, valuable evidence. The (apparent) single origin of Earth life is a remarkable statistical observation hiding in plain sight.
- JohnMakin 2y ago
  > I'm convinced the absence of evidence is, itself, valuable evidence. That isn't how science works. We have an astounding lack of evidence that there is a Flying Spaghetti Monster roaming around the deepest reaches of space, it doesn't indicate anything but the fact that there's a lack of evidence that there is a Flying Spaghetti Monster roaming around the deepest reaches of space. It may not indicate with absolute certainty whether there is or isn't one, but you cannot say its existence is more likely based on lack of evidence for it - that is superstition.
  - aradox66 2y ago
    I think science does actually offer tools beyond pure falsifiability for evaluating truth claims
  - jerf 2y ago
    "Absence of evidence is not evidence of absence" is simply false, however much fun it may be to say. Let us suppose, for instance, that we had indeed scanned over the entire universe and found that there was no evidence for life. Would we then be justified in saying "the absence of evidence is not evidence of absence"? Of course not. What other evidence of absence do you expect to uncover, other than a lack of evidence for existence? Do you expect to go out into space and have some sort of space god hand you a genuine, bona-fide certificate of nonexistence of something? It is important not to overestimate the strength of the absence of evidence, but setting the strength to zero is just as wrong. If we look in many places where we expect to find life, because we have a theory that life is easy and essentially appears the cosmological instant it is possible, and we have a theory that the conditions for life are easy and abundant, yet we look out into the universe and see no evidence of this, yes, we are completely justified in adjusting our understanding of the probabilities involved. The more of the universe we see, and the more it lacks various sorts of life (all the way from the simplest, sparsest bacteria-type life up to galaxy-spanning intelligences, each to their own degree) the more we are justified in coming to conclusions about their probabilities. Another thing people have problems with in this debate is understanding the difference between justified beliefs and true beliefs. If we hypothetically examined all but one-trillionth of the observable universe and found it bereft of any other life, we would be justified in the conclusion that the most likely scenario is that there isn't any. We could end up being wrong if that remaining one-trillionth just so happened to contain other life, but we would still be justified, having collected extensive "absence of evidence". We can not claim that we have seen enough of the universe to know that it is true that there is no other life, and we have not seen enough of it to be justified in claiming there is no bacterial life, but I do feel at this point we are pretty justified in claiming that at least this galaxy and the nearest ones do not have any galaxy-spanning, multi-million-year civilizations in them, for instance. Maybe they're there and they just don't do anything visible, but that's a pretty precise claim.
gxd 2y ago
This topic is near and dear to me. It is so important that I'm working full-time on a game about how a first contact with an extraterrestrial could look like. If you are interested, I just released a free demo with ~2 hours of content: https://store.steampowered.com/app/3040110/Outsider/ https://store.steampowered.com/app/3040110/Outsider/
- jonhohle 2y ago
  I know you’re being serious, but I was really hoping this was a link to the shareware version of Doom.
j_timberlake 2y ago
"Carter was motivated by the timing of our emergence, which we can round off at 4.6 billion years after the formation of our planet. He reasoned that the upper limit for habitability at Earth’s surface is on the order of 5.6 billion years after Earth’s formation, a suspicious fact – why would human origins require a time that approximates the extinction of the biosphere that supports us?" My absolute favorite Fermi's Paradox theory is that life on Earth was evolving too slowly to survive, so aliens sped up the process while hiding themselves, but that came with a variety of problems that humanity bumps into, and the aliens are trying to clean up the mess without destroying humanity's potential for a unique identity. The sci-fi novel practically writes itself.
- Qem 2y ago
  > My absolute favorite Fermi's Paradox theory is that life on Earth was evolving too slowly to survive, so aliens sped up the process while hiding themselves, but that came with a variety of problems that humanity bumps into, and the aliens are trying to clean up the mess without destroying humanity's potential for a unique identity. You need to watch "Jigureul jikyeora!": https://m.imdb.com/pt/title/tt0354668/ https://m.imdb.com/pt/title/tt0354668/
hoseja 2y ago
The planetside wet carbon-based chauvinism is outstanding. We don't even know what goes on inside our own Sun (a place with immense energy flux ripe for sustaining lifeforms, whatever they might be) and these people are looking for a second Earth with little green men. I don't think it's as much scientific curiosity as some deep-seated psychological issue. Life is sustained fire, I don't think it much matters what is burning, just that there is infinite fuel available and a remotest possibility of a spark.

50 points by JPLeRouzic 2y ago

Here's a parameter I don't think the Fermi Equation takes into account: I call it "Fragile Universe", based off of the notion of the "Fragile" or "Vulnerable World Hypothesis" [1]. f_c is the parameter for the fraction of "civilizations that reach the technological level whereby detectable signals may be dispatched", so that handles the "Fragile World Hypothesis". Alien civilizations can wipe themselves out, exhaust resources, etc. before we get to see their detectable signals [2]. What the equation doesn't take into consideration is the possibility that an advanced species can trigger the destruction or total reset of the entire universe, eg. by nucleating the vacuum collapse. The first advanced species to reach that point could kill every species in the universe and start the whole thing over from scratch. This is an extreme version of the anthropic principle [3]. We exist because the universe hasn't been reset yet. By us or otherwise. Presumably we might be the first to get there. Universe fragility could be the reason we don't see aliens. We could be the very first, and we could wind up hitting the reset button. [1] https://nickbostrom.com/papers/vulnerable.pdf https://nickbostrom.com/papers/vulnerable.pdf ; tldr: advanced species can trivially wipe themselves out and will tend to do so. Not just nukes, but in the extreme, your average citizen can create grey goo at home with the press of a button that will turn the entire planet into paper clips. [2] It could be that the time frames in which advanced civilizations emit detectable signals are so geologically small as they shift into non-detectable modes (eg. dark forest, disinterest in expansion, shift into a higher plane of existence, etc.), but that's orthogonal to the discussion. [3] https://en.wikipedia.org/wiki/Anthropic_principle https://en.wikipedia.org/wiki/Anthropic_principle

ziddoap 2y ago
>eg. by nucleating the vacuum collapse. The first advanced species to reach that point could kill every species in the universe and start the whole thing over from scratch. How do you imagine the Universe resetting? Assuming the false vacuum decay occurs, I don't think any species (no matter how advanced) could reset the vacuum state back to a metastable state post-collapse. It does just appear to be the anthropic principle, but with some extra steps.
- echelon 2y ago
  Maybe it doesn't? Maybe there are lots of other universes, and we just happen to be in one of the metastable ones that hasn't collapsed yet.
jebarker 2y ago
Novice question here: What use is there in adding a term like that to the Drake equation? It seems like it's value would be completely uncertain (like other terms in the equation) and so you have overwhelming uncertainty in the output of the equation.
- andrewflnr 2y ago
  Your instinct is largely correct. This is a silly idea.
- simne 2y ago
  Right answer is - we don't know. Unfortunately, Drake equation now is just estimate, without any real data, as humanity just don't know example of any extraterrestrial life at all. And what even more sad, our empty knowledge is not because non-existence of life in Universe, but because our science is very young and we just don't have powerful enough instruments to detect et life. We could only be sure, life was not exist on Moon equatorial stripe on surface, but for example we cannot be sure about deep under-surface and about polar regions.
  - simne 2y ago
    Things are even worse for intelligent life. Because we only could understand et with similar to our level of sci/tech development, but what if we encounter civilization, even one magnitude older than our? For example, now our science have evidences about human civilizations up to somewhere 10k..50k years, and our current civilization oldest evidences are about 5k years. Imagine, how could look our civilization in 500k years? And if we use adequate considerations, human life was appear on Earth ~ 500 thousands years ago, and before was possible reptile civilization, for about 10 millions years, but our Earth become life planet ~ billion years, and exist planets in other star systems, which are tens billions years older than Earth. So what I mean, in our 5k years our civilization decided to re-circling resources and probably in ~ 100 years we could implement this decision and will become invisible to ets of our level. Imagine, what technologies would be available for magnitude older civilization. Could someone be sure about possibility of detection so much newer technologies? You may hear classification of seti scientists as Cygnus, Cancer and Pike. What I want to say, civilizations younger than our are detectable for us, but older are detectable only if them decided to contact us.
bluGill 2y ago
The universe is 93 billion light years across. No alien can reset it within time spans that matter to our solar system which has maybe 8 billion years left before our sun dies)
wat10000 2y ago
I don't think that solves it. The Fermi paradox is that based on the probabilities we estimate, we should see lots of aliens, and we don't. Thus something in our estimates must be wrong, but we don't know what. This fragility idea just shifts it from "we should see lots of aliens and we don't" to "the universe should have been destroyed by now and it hasn't been."
- DennisP 2y ago
  Actually the Drake equation may not say that: > When we take account of realistic uncertainty, replacing point estimates by probability distributions that reflect current scientific understanding, we find no reason to be highly confident that the galaxy (or observable universe) contains other civilizations, and thus no longer find our observations in conflict with our prior probabilities....When we update this prior in light of the Fermi observation, we find a substantial probability that we are alone in our galaxy, and perhaps even in our observable universe (53%–99.6% and 39%–85% respectively). ’ https://arxiv.org/abs/1806.02404 https://arxiv.org/abs/1806.02404

AnotherGoodName 2y ago

The steps don't have to be that hard for us to be unique. There are 10^22 to 10^24 stars in the Universe (a big range of uncertainty there but it doesn't matter for this point). That sounds like a lot but anyone with knowledge of combinatronics would immediately say holy shit that's a small number. Cryptography buffs are probably looking at that going "that can't be right, it's a tiny number", you divide it by 10 repeatedly, 24 times in fact and you're down to nothing. 24 not-at-all 'hard' steps and we're probably alone. You've probably heard "there's soooo many stars in the universe there has to be other life out there". There really isn't that many in terms of probability.

A_D_E_P_T 2y ago
This is too facile. The Copernican principle assumes that we are not in a spatially or temporally privileged position, and there are no obvious hard steps -- to say nothing of 24. It's frankly bizarre to go from there to "we are unique among 10^22 stars."
- AnotherGoodName 2y ago
  Having thoughts around how many stars are in the observable universe is a very reasonable starting point. Even without a privileged position the observable universe is still well defined in an expanding universe - at some boundary other stars are moving away too fast to be observed. So we can absolutely state this.
- DennisP 2y ago
  In this case the Copernican principle is at odds with the anthropic principle. If there were only one place in the universe with intelligent life, then necessarily that's where we would be. GP may be thinking of this paper, which uses a reasonable probability distribution for each parameter in the Drake equation, and finds a decent chance that there is no other technological civilization in the observable universe: https://arxiv.org/abs/1806.02404 https://arxiv.org/abs/1806.02404
  - jovial_cavalier 2y ago

A_D_E_P_T 2y ago

On timescales of billions of years, we don't know if any of those steps are "hard," "easy," or "inevitable." As the first commenter to that article notes at the link, we have only a single datapoint. It's certainly unclear that photosynthesis is an ironclad requirement for life, and, in any case, it evolved multiple times in parallel on Earth. (Anoxygenic photosynthesis in fact evolved, de novo, more than once.) I'd add that it's also by no means a given that life, broadly defined, can only evolve around a sunlike star. Speculation around "hard steps" is pseud naval gazing until we gather more datapoints. It's not even valuable as speculation -- except perhaps as an exercise in countering sloppy thinking.

bluGill 2y ago
> I'd add that it's also by no means a given that life, broadly defined, can only evolve around a sunlike star. Not a given, but not unreasonable either. Larger stars die faster so they probably won't be around long enough for life. Smaller stars last longer, but they also emit less energy and so there is less likely to be higher life forms just because there isn't enough energy to support life. Of course life might not be like we know it, but carbon and water are very common in the universe compared to most of the other options and so they are more likely.
- jdhwosnhw 2y ago
  > Smaller stars last longer, but they also emit less energy and so there is less likely to be higher life forms just because there isn't enough energy to support life. This isn’t really true. The energy density at a planet’s surface is a function of both the star’s luminosity and the planet’s distance. Most star’s (at least in the Milky Way) are small, and most stars have planets in orbits closer than is Earth’s. The so called “Goldilocks zone” is expected to have at least one planet in it for a very large number of stars (again, at least in our galaxy).
  - Teever 2y ago
    > most stars have planets in orbits closer than is Earth’s. I don't think that this is true. IIRC it's an artifact of the techniques we use to detect extrasolar planets -- our techniques are biased to detect planets that are closer to their stars than further away,

perihelions 2y ago

- "The fact that it did happen here tells us nothing more than that, and until we dig out evidence of a ‘second genesis,’ perhaps here in our own Solar System inside an icy moon, or on Mars, we can form no firm conclusions." I'm convinced the absence of evidence is, itself, valuable evidence. The (apparent) single origin of Earth life is a remarkable statistical observation hiding in plain sight.

JohnMakin 2y ago
> I'm convinced the absence of evidence is, itself, valuable evidence. That isn't how science works. We have an astounding lack of evidence that there is a Flying Spaghetti Monster roaming around the deepest reaches of space, it doesn't indicate anything but the fact that there's a lack of evidence that there is a Flying Spaghetti Monster roaming around the deepest reaches of space. It may not indicate with absolute certainty whether there is or isn't one, but you cannot say its existence is more likely based on lack of evidence for it - that is superstition.
- aradox66 2y ago
  I think science does actually offer tools beyond pure falsifiability for evaluating truth claims
- jerf 2y ago
  "Absence of evidence is not evidence of absence" is simply false, however much fun it may be to say. Let us suppose, for instance, that we had indeed scanned over the entire universe and found that there was no evidence for life. Would we then be justified in saying "the absence of evidence is not evidence of absence"? Of course not. What other evidence of absence do you expect to uncover, other than a lack of evidence for existence? Do you expect to go out into space and have some sort of space god hand you a genuine, bona-fide certificate of nonexistence of something? It is important not to overestimate the strength of the absence of evidence, but setting the strength to zero is just as wrong. If we look in many places where we expect to find life, because we have a theory that life is easy and essentially appears the cosmological instant it is possible, and we have a theory that the conditions for life are easy and abundant, yet we look out into the universe and see no evidence of this, yes, we are completely justified in adjusting our understanding of the probabilities involved. The more of the universe we see, and the more it lacks various sorts of life (all the way from the simplest, sparsest bacteria-type life up to galaxy-spanning intelligences, each to their own degree) the more we are justified in coming to conclusions about their probabilities. Another thing people have problems with in this debate is understanding the difference between justified beliefs and true beliefs. If we hypothetically examined all but one-trillionth of the observable universe and found it bereft of any other life, we would be justified in the conclusion that the most likely scenario is that there isn't any. We could end up being wrong if that remaining one-trillionth just so happened to contain other life, but we would still be justified, having collected extensive "absence of evidence". We can not claim that we have seen enough of the universe to know that it is true that there is no other life, and we have not seen enough of it to be justified in claiming there is no bacterial life, but I do feel at this point we are pretty justified in claiming that at least this galaxy and the nearest ones do not have any galaxy-spanning, multi-million-year civilizations in them, for instance. Maybe they're there and they just don't do anything visible, but that's a pretty precise claim.

gxd 2y ago

This topic is near and dear to me. It is so important that I'm working full-time on a game about how a first contact with an extraterrestrial could look like. If you are interested, I just released a free demo with ~2 hours of content: https://store.steampowered.com/app/3040110/Outsider/ https://store.steampowered.com/app/3040110/Outsider/

jonhohle 2y ago
I know you’re being serious, but I was really hoping this was a link to the shareware version of Doom.

j_timberlake 2y ago

"Carter was motivated by the timing of our emergence, which we can round off at 4.6 billion years after the formation of our planet. He reasoned that the upper limit for habitability at Earth’s surface is on the order of 5.6 billion years after Earth’s formation, a suspicious fact – why would human origins require a time that approximates the extinction of the biosphere that supports us?" My absolute favorite Fermi's Paradox theory is that life on Earth was evolving too slowly to survive, so aliens sped up the process while hiding themselves, but that came with a variety of problems that humanity bumps into, and the aliens are trying to clean up the mess without destroying humanity's potential for a unique identity. The sci-fi novel practically writes itself.

Qem 2y ago
> My absolute favorite Fermi's Paradox theory is that life on Earth was evolving too slowly to survive, so aliens sped up the process while hiding themselves, but that came with a variety of problems that humanity bumps into, and the aliens are trying to clean up the mess without destroying humanity's potential for a unique identity. You need to watch "Jigureul jikyeora!": https://m.imdb.com/pt/title/tt0354668/ https://m.imdb.com/pt/title/tt0354668/

hoseja 2y ago

The planetside wet carbon-based chauvinism is outstanding. We don't even know what goes on inside our own Sun (a place with immense energy flux ripe for sustaining lifeforms, whatever they might be) and these people are looking for a second Earth with little green men. I don't think it's as much scientific curiosity as some deep-seated psychological issue. Life is sustained fire, I don't think it much matters what is burning, just that there is infinite fuel available and a remotest possibility of a spark.