We literally split the atom and with it, came up with the cleanest and cheapest way to support a large chunk of our energetic needs.

Then some people did a big boom with it, and then a cartoon decided to draw it as green rods of evil energy, and there, the entire world decided to stop using it. And we've not started doing it again properly for several decades, all while we uproot carbon off the biosphere and the ground and into the air so we can boil ourselves to a climatic disaster.

Aliens would find nothing worth respecting.