Why are the conditions for alien life to evolve the same as ours? Why can’t they evolve without water, or extremely far from their sun? Is there a reason for this or is it just because our only example is ourselves?

Question

Idk if to put biology or planetary science so ye.

In: Biology

Answer 1

It doesn’t have to and we have theories about finding single cell organisms on the Methane seas under the ice sheets of Titan.

But with complex life it’s pretty likely that it needs similar conditions to earth. First and foremost because carbon is one of the most available things out there and it is incredibly at forming bonds with other atoms. Others like Silicium or Selen might be also atoms for it but much less available. Sure there might be a fluke galaxy out there where those two elements are rather common but right now there is no indication for it.

Laws of physics, they are similar around the galaxy and in regions were the go crazy like black holes life of any kind is unlikely to form. Other than that you need some amount of gravity on planets to hold the atmosphere in which ever composition, probably some decent magnetic field against the worst radiation from the local star and some form of energy, most likely the local star but a huge molten core might also do the trick. But it needs some form of stability which extreme seismic active planets don’t seem to have.

For complex life you also likely need a food chain, because it’s unlikely that conscious life will spring out of nowhere. So you need develop from simple to complex.

Is it possible for life to forgo some or all of these, well maybe. But it seems unlikely, and given that the universe is only becoming less hostile to life in general (e.g., less super novae, less gamma ray burst, right star sizes, etc.), we cannot know for sure but can deduct from the laws of physics and go from there.