Ok, so nuclear fusion is given by the formula E=MC2, where E = Energy, M = Rest mass and C = 299792458. To my understanding, this means that if two protons collide under the incredibly high speeds/temperatures(like they do in the sun), they will fuse, having reduced mass and that mass is converted to energy. But, I thought that energy could not be created or lost, it is always converted. In a nuclear reactor, nuclear energy is converted to thermal energy. In beta decay, if an electron is slowed by an atom, that lost kinetic energy is converted to bremsstrahlung X-rays(Electromagnetic radiation). So, why is energy created from mass? I can understand why antimatter can create energy from annihilation, basically 1 + -1 = 0 + γ + γ. Is it similar? Thanks.