are we alone in the universe?

[KenWittlief]

Originally Posted by Marc P.

...Also, the assumption that all life is based on DNA is a bit presumptuous. They key words are "life as we know it." Like Ken, I don't want this to become a religious debate, but let's say for the sake of argument that life on earth did start from a spontaneous chemical reaction, producing bacteria which then evolved into higher life as conditions became more favorable. Given that if all life rose from simple amino acids and then bacteria, it only makes sense that all life here would share the same structure in DNA. However, the theoretical existence of silicon based life-forms means there may be life in places carbon-based life couldn't possibly survive. In any case, my feeling is there's really not enough data either way to draw any sure conclusions.

it may seem presumtuous at first, but DNA based life is the only form of life in existance on the earth, the moon, on Mars - everywhere we have been able to investigate so far

and its incredibly complex. If simpler life forms could exists then probability says they would have spontaiously been created long before DNA life would, and there would be billions and billions of different life forms - all based on different molecular arrangements

but we find none, nothing here, only DNA life

now if lifeforms other than DNA based can exist, but they are more complex than DNA, then the probability equations hold true for them. They would be even more unlikely to spring into existance spontainously than we were

so (according to statisics) they are not out there either.