Question

In a nuclear fission, what are the great amounts of energy produced from? :)

Answer 1

Nuclear fission is when elements such as uranium and plutonium are split apart, it unfortunately produces radioactive waste but it's a lot easier to control, so we use it in modern nuclear power plants. :)

Answer 2

From a loss of mass. (E = mc^2). Each proton and neutron in the uranium becomes something like half a percent lighter (no particles go missing, they all get lighter). This is in direct violation "conservation of mass" - mass is destroyed. Likewise, "conservation of energy" is violated - energy is created. It turns out that what people thought were two separate laws (and things) are really just two forms of the same thing. The mass can be converted into energy.