Life evolved on Earth. The idea that it has never done that elsewhere is ridiculous.
I was going to question this, just because I think people often jump to conclusions based on the universe being very large, but as I did just a bit of research it does seem like nothing too unlikely happened to create Earth. You seem to need liquid water. Maybe that water is generated on the planet or maybe it’s delivered by impacts with icy meteorites or asteroids. We have yet to find another planet with liquid oceans, but it’s hard to imagine why it would be so unlikely for enough Earth-like planets to have sprung up to have a good chance of fostering life. The fact we haven’t found an ocean world would seem to speak more to the massive limitations of our knowledge of other planets. You need other things for life as well, but the same argument seems to follow, in that none of the requirements seem like they have a reason to be that rare. But as limited as our science is, and as limited as my understanding of the science is, I have to admit I really do not know what to think. I don’t think our statistical intuitions are useful when thinking about probabilities of planetary or astronomical phenomena.
Yes, it seems pretty untenable that rare earth is the explanation for the lack of evidence of any life outside of Earth. But even if it is true that we’re the only life in the observable universe, the universe is still much bigger, and in many physicists opinion, probably infinite.
The fact that life seems to have evolved on Earth as soon as it was possible to is some evidence that abiogenesis is not the bottleneck. But the usefulness of this observation depends on the distribution of other things we don’t know. For example, if on planets where life evolves later, life never makes it to human-level intelligence before the planet becomes uninhabitable, then our early abiogenesis is survivorship bias, rather than something we should expect to be in the center of the distribution of when abiogenesis happens on a planet where it is possible.
I was going to question this, just because I think people often jump to conclusions based on the universe being very large, but as I did just a bit of research it does seem like nothing too unlikely happened to create Earth. You seem to need liquid water. Maybe that water is generated on the planet or maybe it’s delivered by impacts with icy meteorites or asteroids. We have yet to find another planet with liquid oceans, but it’s hard to imagine why it would be so unlikely for enough Earth-like planets to have sprung up to have a good chance of fostering life. The fact we haven’t found an ocean world would seem to speak more to the massive limitations of our knowledge of other planets. You need other things for life as well, but the same argument seems to follow, in that none of the requirements seem like they have a reason to be that rare. But as limited as our science is, and as limited as my understanding of the science is, I have to admit I really do not know what to think. I don’t think our statistical intuitions are useful when thinking about probabilities of planetary or astronomical phenomena.
Yes, it seems pretty untenable that rare earth is the explanation for the lack of evidence of any life outside of Earth. But even if it is true that we’re the only life in the observable universe, the universe is still much bigger, and in many physicists opinion, probably infinite.
The fact that life seems to have evolved on Earth as soon as it was possible to is some evidence that abiogenesis is not the bottleneck. But the usefulness of this observation depends on the distribution of other things we don’t know. For example, if on planets where life evolves later, life never makes it to human-level intelligence before the planet becomes uninhabitable, then our early abiogenesis is survivorship bias, rather than something we should expect to be in the center of the distribution of when abiogenesis happens on a planet where it is possible.