[jwalsh07]

You do realize it is impossible to create a setting that was identical to the earths early environment in the lab. It is also impossible to mimic billions of years of time.

True, it can never be observed, it can never be replicated, it can never be repeated. So, how is it science?

[Clorinox]

"True, it can never be observed, it can never be replicated, it can never be repeated. So, how is it science?"

It can be observed if we find a planet or moon with conditions similar to what early Earth might have been like. We just don't have the ability to do that research at this time.