Assuming they wanted to do all that travelling, assuming that they’re colonisers like us, and assuming that they want to be seen by the methods we have available for looking. That’s also assuming they’re not every bit as destructive as us, that they didn’t kill themselves during the few centuries where space travel…

How is it possible to put a probability on the advent of biochemistry as it functions in this universe if we have got no access to parallel universes where the laws of physics differ? We have no reference point against which to form anything even close to a method for calculating the probability of life arising…

Explain to me how you can put a probability equation on the advent of biochemistry as it functions in this universe. Have you got access to parallel universes where the laws of physics differ? Can you also travel through time? If not, you have no reference point against which to form anything even close to a method…