I’m not super sure. If I recall correctly, we’ve known for a while that something was going on, because surface hearing alone couldn’t account for all of the water evaporating from oceans, but we couldn’t tell what. In defense of humanity here, the concept of photons interacting with something as comparably massive as molecules is kinda wild. We were caught way off guard when the photoelectric effect was announced, and that’s photons interacting with whole atoms instead of just elementary particles. The idea of the photomolecular effect is thus even wilder.
It also seems like there’s some sort of unlock mechanism for what civs will be available for you to choose from in the next era - you’ll assumably have to do certain things in an era to unlock specific civs for the next era