Question

at the right temperature, four hydrogen nuclei fuse together in a series of reactions to form a nucleus of the next - heavier element, helium, and other subatomic particles. what does this nuclear fusion signal?

Explanation:

Nuclear fusion is a process where lighter - weight nuclei combine to form a heavier - weight nucleus, releasing a large amount of energy. In the case of hydrogen nuclei fusing to form helium, it signals the conversion of mass into energy according to Einstein's mass - energy equivalence principle ($E = mc^{2}$), and it is the energy - generating process in stars like our Sun.

Answer:

The conversion of mass into energy and the energy - generating process in stars.