No ET! Ever?

[Rhondazvous]

Evolution recognizes that certain traits develop under certain conditions and other traits develop under other conditions. Suppose there were only one condition on Earth. Say the entire Earth was like it is in Alaska or the North pole. We could presuppose that life cannot exist without some way to protect itself against cold. If we never encounter any other conditions, our presupposition remains safe.

Actually, what we are doing is using deductions based on existing empirical knowledge to allocate limited research resource to maximize the chance of success, not assuming everything out there must conform to deductions based on existing empirical knowledge.

If we live on a plant where the whole environment is like the North Pole, then we have empirical knowledge that life is possible under North Pole like conditions.   Let's suppose we have no great confidence in our chemistry, so we can't say whether life is possible if it were 70 degrees warmer.   We have limited research resource, and we are just starting to look for alien life, how do we proceed?   Do we dissipate our limited resources on the infinite varieties of environment not known to be able to support life, or do we focus most of them on environment similar to ours, which we already know can support life?

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I'm not sure how to make your conditions for life independent from Earth conditions. Can we say no other model is possible under any conditions when we haven't seen any other model?

The difference between science and religion is the religionist thinks he knows everything and dismisses anything that falls outside his accept truth. But the scientist is open to whatever presents itself as valid fact, even if he hitherto though it impossible.

I agree with the first part of what you said. With limited resources, it's best that we work with what we know. Not on speculations such as I presented. I was just giving us food for thought, not for spending money.

Having said that, I still have one little caveat. The idea that chemistry is independent of environment. Would you not say that a chemical will react differently when environmental conditions such as temperature or the presence of certain other chemicals is different? So being, a chemical that doesn't evolve into life on Earth might do so in other conditions. Again, this is speculation for the future. I'm not suggesting that we spend resources on it at this time.


Chemistry is independent of earth conditions.  We make our deduction based on chemistry, not earth conditions.