Nuclear fusion is the process where light atomic nuclei combine to form heavier ones, releasing a gargantuan amount of energy. This very reaction is what powers the Sun and all other stars. Deep inside a star, extreme gravity and temperatures of millions of degrees force hydrogen nuclei to overcome their natural repulsion and fuse into helium. The mass of the resulting helium is slightly less than the combined mass of the original particles, and this lost mass is converted into pure radiative en

Energy Secretary says 'there may not be' a nuclear agreement with Iran