RE: Aliens - Are they out there? Have they visited us? And related questions
December 17, 2010 at 11:24 am
(This post was last modified: December 17, 2010 at 11:33 am by Anomalocaris.)
@welsh cake
It appears Jupiter like planets are very common in planetary systems. Very large Jovian planets are to be found in majority of the planetary system we know of. So I think the odds of a planetary system having large planets to sweep up debris from primodia disk and deflect later comets is high.
Also, I think you unnecessarily narrow the range of planets that might harbor life. There is no reason to suppose, for example, that large Jovian planets with long lasting internal heat sources can not support life in it's own atmosphere without being in the goldilock zone. Also there is no reason to suppose a Jovian system might not harbor life on it's moons, with energy provided by tidal flexing of the moons resulting from gravitational interaction between different moons in the same system, such as we find on Io and Europa. We have no idea what is the ratio of worlds that could support life with energy sources other than it's sun to the worlds that is in goldilock zones around the sun. It may well be that majority of life sustaining environments are not in the goldilock zone.
As to the chances of intelligent life evolving and not destroying itself. At this point we have a sample of only 1. We don't know how long it takes to detect earth from the average distance any civilizations are separated from each other in the universe. We don't know how long it takes for a typical civilization to get around to visiting enough planets to have a high chance of visiting earth should that civilization evolve at a specific distance from earth. It seems unwarranted to extrapolate from such slim collection of data a position so far from neutrality as "infinitesimal". Also, exactly how much is infinitesimal? Is it larger than 1 when multiplied by 6e18?
It appears Jupiter like planets are very common in planetary systems. Very large Jovian planets are to be found in majority of the planetary system we know of. So I think the odds of a planetary system having large planets to sweep up debris from primodia disk and deflect later comets is high.
Also, I think you unnecessarily narrow the range of planets that might harbor life. There is no reason to suppose, for example, that large Jovian planets with long lasting internal heat sources can not support life in it's own atmosphere without being in the goldilock zone. Also there is no reason to suppose a Jovian system might not harbor life on it's moons, with energy provided by tidal flexing of the moons resulting from gravitational interaction between different moons in the same system, such as we find on Io and Europa. We have no idea what is the ratio of worlds that could support life with energy sources other than it's sun to the worlds that is in goldilock zones around the sun. It may well be that majority of life sustaining environments are not in the goldilock zone.
As to the chances of intelligent life evolving and not destroying itself. At this point we have a sample of only 1. We don't know how long it takes to detect earth from the average distance any civilizations are separated from each other in the universe. We don't know how long it takes for a typical civilization to get around to visiting enough planets to have a high chance of visiting earth should that civilization evolve at a specific distance from earth. It seems unwarranted to extrapolate from such slim collection of data a position so far from neutrality as "infinitesimal". Also, exactly how much is infinitesimal? Is it larger than 1 when multiplied by 6e18?
