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Why would complex life depend on plate tectonics?

by dnsco 10y ago

rwallace 10y ago
Partial summary: http://hyperphysics.phy-astr.gsu.edu/hbase/geophys/platelif.html http://hyperphysics.phy-astr.gsu.edu/hbase/geophys/platelif....
- jessriedel 10y ago
  These are speculative and rather weak. Like most theory in this area, it takes the form "Look at these features of the development of life as we know at; if they weren't there, it couldn't exist!". But of course, they are simply unable to imagine, much less predict, what happens in dramatically different conditions. Also, talk about correlation does not equal causation at your link: > The basic structure of the Earth, aided by plate tectonics, makes possible the Earth's magnetic field. Neither Venus nor Mars has such a magnetic field. Venus has core and molten regions like the Earth, but a very slow rate of rotation. It produces neither plate tectonics or a magnetic field. Mars has volcanism, but limited to a small number of spectacularly large volcanoes like Olympus Mons. It's magnetic field is weak despite a rotation period similar to that of the Earth. This suggests that the molten nature of the Earth's mantle that facilitates plate tectonics is also essential for the operation of the dynamo that produces the magnetic field. I mean, N=3 !
  - rwallace 10y ago
    Okay, but which of the following two positions are you arguing for? 1. We don't have enough data about other solar systems, so we don't know where complex life might exist. 2. We don't have enough data about other solar systems, so complex life probably exists all over the place. If you're arguing for the first position, fair enough; I might not entirely agree, but it is at least reasonable. But I see too many people arguing for the second position, taking scarcity of data as a license to believe what they want to believe.
    - jessriedel 10y ago
      The first. I think the most likely resolution to the fermi paradox, which is not that paradoxical, is just that abiogenesis is a galactically rare event. Other proposed filters, like the advent of sexual reproduction, eukaryotes, or intelligence, seem much less robust to a failure of imagination.
      - rwallace 10y ago
        Fair enough, that's a reasonable position. My opinion, for what it's worth, is that every step is a hard step, because it's not just a matter of time elapsed to the next one, but of each step having to be taken in just such a way as to set the right preconditions for all the subsequent ones.

Why would complex life depend on plate tectonics?

by dnsco 10y ago

Why would complex life depend on plate tectonics?

Partial summary: http://hyperphysics.phy-astr.gsu.edu/hbase/geophys/platelif.html http://hyperphysics.phy-astr.gsu.edu/hbase/geophys/platelif....

jessriedel 10y ago
These are speculative and rather weak. Like most theory in this area, it takes the form "Look at these features of the development of life as we know at; if they weren't there, it couldn't exist!". But of course, they are simply unable to imagine, much less predict, what happens in dramatically different conditions. Also, talk about correlation does not equal causation at your link: > The basic structure of the Earth, aided by plate tectonics, makes possible the Earth's magnetic field. Neither Venus nor Mars has such a magnetic field. Venus has core and molten regions like the Earth, but a very slow rate of rotation. It produces neither plate tectonics or a magnetic field. Mars has volcanism, but limited to a small number of spectacularly large volcanoes like Olympus Mons. It's magnetic field is weak despite a rotation period similar to that of the Earth. This suggests that the molten nature of the Earth's mantle that facilitates plate tectonics is also essential for the operation of the dynamo that produces the magnetic field. I mean, N=3 !
- rwallace 10y ago
  Okay, but which of the following two positions are you arguing for? 1. We don't have enough data about other solar systems, so we don't know where complex life might exist. 2. We don't have enough data about other solar systems, so complex life probably exists all over the place. If you're arguing for the first position, fair enough; I might not entirely agree, but it is at least reasonable. But I see too many people arguing for the second position, taking scarcity of data as a license to believe what they want to believe.
  - jessriedel 10y ago
    The first. I think the most likely resolution to the fermi paradox, which is not that paradoxical, is just that abiogenesis is a galactically rare event. Other proposed filters, like the advent of sexual reproduction, eukaryotes, or intelligence, seem much less robust to a failure of imagination.
    - rwallace 10y ago
      Fair enough, that's a reasonable position. My opinion, for what it's worth, is that every step is a hard step, because it's not just a matter of time elapsed to the next one, but of each step having to be taken in just such a way as to set the right preconditions for all the subsequent ones.