I'll buy into it when they start seeing ATM's spontaneously assembling. I mean, it's an infinite universe, isn't it???
if i remember my courses in college, each chemical will absorb and release energy (say light) in a unique way. If you know what the pattern should look like for a certain chemical you can identify it when you see that pattern coming from space.
One of the tests we did was look at light coming into boston from the sun. It showed a large amount of mercury in the air.
I love the term "Building Blocks of Life", I guess that means that given time and chance they will come together to make life as we know it.
Let's give it a big head start, I'll set out a ham sandwich and see how long it takes to evolve into something that can do the calculus.