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There are plausible theories about how life arose on Earth. If you want to assume it came from somewhere else, you either have to invoke some kind of magic, or

There are plausible theories about how life arose on Earth. If you want to assume it came from somewhere else, you either have to invoke some kind of magic, or assume it happened somewhat along the lines that it would have done on Earth, then arrived somehow. It just kicks the can down the road without solving anything, IMO.

swift 9y ago
The hypothesis that life on Earth originated elsewhere is somewhat independent of abiogenesis, really. At least in my experience, most supporters of the former also support the latter.
avian 9y ago
> It just kicks the can down the road without solving anything Panspermia is an attempt to explain one inconsistency in our observations so far: it appears that life spontaneously emerging from inorganics is hugely unlikely. On other hand, geological records show that life appeared on Earth very soon after it became viable. If life on Earth originated somewhere else, then this discrepancy can be made to disappear. For example, abiogenesis only needs to arise once within a large radius around Earth and within a much broader time margin. Hence it can be a very rare event while still not making early life on Earth a unique event in the universe. I don't personally believe panspermia is likely. But it is a valid theory (although without much supporting evidence as far as I know).
- reubenswartz 9y ago
  It's certainly a valid hypothesis. And stronger (any?) evidence for possible life on Mars or Venus would possibly support this. With a sample size of 1, and loose record-keeping from ~4B years ago, it's hard to tell, but we don't really know if it took life 1 day or 500M years to evolve once it was chemically/geologically viable. We do know that life was very primitive for > 1B years (not even eukaryotic, let alone multicellular). We also know that space isn't teaming with little biologically active spores from other worlds (unless it is and the government is covering it up, of course), which suggests that in the vastness of space, life doesn't really hitch rides on asteroids or comets and colonize the galaxy accidentally. And if some beings were doing this on purpose, why not send more advanced life forms or robots?

swift 9y ago

The hypothesis that life on Earth originated elsewhere is somewhat independent of abiogenesis, really. At least in my experience, most supporters of the former also support the latter.

avian 9y ago

> It just kicks the can down the road without solving anything Panspermia is an attempt to explain one inconsistency in our observations so far: it appears that life spontaneously emerging from inorganics is hugely unlikely. On other hand, geological records show that life appeared on Earth very soon after it became viable. If life on Earth originated somewhere else, then this discrepancy can be made to disappear. For example, abiogenesis only needs to arise once within a large radius around Earth and within a much broader time margin. Hence it can be a very rare event while still not making early life on Earth a unique event in the universe. I don't personally believe panspermia is likely. But it is a valid theory (although without much supporting evidence as far as I know).

reubenswartz 9y ago
It's certainly a valid hypothesis. And stronger (any?) evidence for possible life on Mars or Venus would possibly support this. With a sample size of 1, and loose record-keeping from ~4B years ago, it's hard to tell, but we don't really know if it took life 1 day or 500M years to evolve once it was chemically/geologically viable. We do know that life was very primitive for > 1B years (not even eukaryotic, let alone multicellular). We also know that space isn't teaming with little biologically active spores from other worlds (unless it is and the government is covering it up, of course), which suggests that in the vastness of space, life doesn't really hitch rides on asteroids or comets and colonize the galaxy accidentally. And if some beings were doing this on purpose, why not send more advanced life forms or robots?