[macspoofing]

An alien race with no notion of life (as we know it) would see us as nothing more than a natural biochemical reaction process that, as one of its byproducts, manipulated a local environment to split and release energy from atomic nuclei.

There is potential energy locked in multitudes of structures (from chemical bonds, to atomic nuclei). A simple chemical reaction may need a relatively small catalyst to free this energy. For example, a mix of oxygen and hydrocarbons will need a small spark - which can be easily provided through a natural process (e.g. lighting).

To release atomic energy, the catalyst that is needed is a highly complex and organized structure that cannot be achieved with a natural process like lighting, but instead required a reaction that lasted billions of years guided by natural selection. Natural selection progressively and incrementally found improved catalytic structures (for lack of a better phrase) to free previously unachievable energies. But because there is no free lunch, as we're accessing these higher energy levels we're actually accelerating global entropy and speeding up the heat death of the universe.

>By the way, a reaction concerning splitting of atoms is not called a chemical reaction: it's a nuclear reaction.

Well ... yes, but in our example, it is a chemical reaction (i.e. us) that serves as a catalyst to start the nuclear reaction.