Quote:
Originally Posted by ZeroID
Your first comment re the moon is still being debated and there some heavy elements on the moon
Just based on sheer numbers there has to be another earth like planet out there. At what stage it is at or whether it has life, who knows but the odds are it exists.
Again, you are assuming that the life form will require similar conditions to ourselves. In a hotter environment Silicon could be the base rather than Carbon for a life form, look at the periodic table and you will see why.
Keep your minds open, there is more to this universe than we can imagine yet.
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Hi Pete,
My understanding is that the question of the moon having come from the earth - which was a nutty idea when first proposed - wound up being conclusively proved by isotope analysis of the samples brought back from the moon. Any debate on the issue would thus be very much at the margin.
Silicon based life? We live on a silicon planet which in the past was very much hotter than today. It didn't arise here, and I've seen counter arguments to the view that it could exist based on information exchange between molecules, suggesting that it is extremely unlikely to have occurred - or may eventually occur somewhere after tens of billions of years.
As for the odds being in favour of an earth-like planet out there, well 90% of stars are small red ones ruling out anything earth-like because of tidal locking in the habitable zone. Then there is a very tiny band around galaxies where earth sized planets can form (further in towards the centre, rocky planets are much bigger, further out away from centre and they are much smaller). Which cuts the candidate stars with possible earth-like planets down considerably. Add to that the supposed fluke event of a large body hitting the planet and forming a huge moon, which keeps the planet very stable in terms of axial tilt, and the odds start getting very tiny - like a few possible earth-like planets in the galaxy (or even less - one earth-like planet per number off galaxies).
Add to that that there was once a time when species of dinosaurs ruled the earth for 160 million years, and in that entire time never managed to tie two sticks together, much less light a fire.
I think SETI types are extreme optimists.
Regards,
Renato