"uranium"

Prehistoric civilization have always been the talk of the town, and it's no wonder - after all, humans have been around for so short a time in the history of the planet that if we were to compress the history of the planet into a single day, then humans would probably only appear in the last two minutes of that day. In the past, there have been frequent claims of the discovery of suspected prehistoric civilization, the most notable of which would be a two-billion-year-old nuclear reactor.

The more "nucleons" an atomic nucleus contains, the greater its mass, but scientists have found that the average mass of the "nucleons" of different elements is different

If mankind can master the method of extracting uranium from seawater in large quantities in the future, there will be enough uranium on the earth to last for tens of thousands of years, even hundreds of thousands of years!