Quote (TitaniumOxide @ 13 Jan 2010 18:59)
See earth is not a good model because we are just the right size, at the right distance, and with the right sized star. whos to say there isnt a planet out there that is bigger than earth, at its right distance from its right sized star?
as for ANY life forms, scientists are almost certain there was once life on mars and simple bacteria is probably quite frequent but given how little we know about the cosmos we just havent found any other yet. and even though mars is so close, the fossilized bacteria was by chance that got to earth.
The other thing i wanna say that supports life in other parts of the universe is amino acids. Theories have suggested that amino acids arrived from outer space. this is likely because there are waaay more amino acids in space than on earth. im not saying that our chunk of rock didnt have its own amino acids to begin with but it is more probable to say that a rock chanced by and struck the earth leaving its amino acids. who knows if another rock crashed into a planet out there somehwere and gave that planet some much needed amino acids to create life?
No one is saying there isn't. But the size of a planet does matter. Bigger planets are usually gas giants, unable to support life as we know it.
The fact is that the universe is extremely big. And it helps to narrow your search down a little to increase the chance of discovering life. We simply do not have time to thoroughly investigate every single planet regardless of its size, distance, etc. And from what we know there is a bigger chance of life emerging on an earth like planet than there is on something that is not earth like at all. So why waste the precious little resources we have searching for every alternative and possibility rather than using those resources to look for something we understand.