“Where and when would you most like to visit to witness and analyse an event in Earth’s history?” Suppose you have a space-time machine to (safely and comfortably) watch an event unfold; which event would you most like to see? Why? What do we already know or hypothesize about that event that appeals to you, or that you would like to test? What would be the result, the upshot, of knowing more about this event?

France, ~3.5Ga

Right then. My choice is difficult to pin down an exact date for, in fact that’s one of the reasons it would be worth going back to try and see. Somewhere in the vicinity of 3.5 Billion years ago (give or take a few hundred million years), in a puddle of goo struck by lightning (probably), life formed. Our knowledge about this event is understandably very very shaky, due to both the distance back in time, and the lack of preservation of the kind of biological activity we’re interested in. The rock record isn’t very useful here; past a certain point too much has been metamorphosed, and organic molecules broken down too much to be informative. We can tell some things about early life, but so far at least, the origins of life are a mystery to us beyond attempts at experimental recreation.

Samples taken every few million years and run through a GC-MS could tell us a lot about the formation of life on earth. Hopefully nailing down the exact mechanism of what exactly happened (whether some sort of chemical assemblage in primordial “soup” or a more esoteric mechanism such as panspermia or exogenesis). Wikipedia has a decent description of the various theories about early life.

Of course, if we did have time travel, and it were possible to change the future, this would be a phenomenally bad idea. As years of Star Trek and other science fiction have shown us; time travel can only end badly…