# Does matter turning into energy, or vice versa, violate the Law of Conservation? [duplicate]

I'm new to physics. And I have curiously wondering about the relationship between matter and energy. From what I understand, one can create the other, but is it truly creating or just aiding in the process?

• What scale are you interested in, and how close to the truth do you want to get? For normal human-scale activities, conservation is the law. For very big (galactic complex scale) or very small (quantum mechanical), they get a little bit fluid and require a bit more math to wrap our heads around. Dec 9, 2019 at 19:25

## 1 Answer

Matter can definitely be created without violating conservation of energy. All massive particles (e.g electrons, quarks, etc) have a minimum energy called their rest energy, which is given by $$E=mc^2$$. This energy is stored as the mass of the particle. A particle can be created as long as there is energy at least equal to its rest energy, so that energy is conserved, and all other conservation laws are obeyed (e.g momentum, charge, lepton number, etc). Matter can also be destroyed to release energy. The rest energy of the particles is released and photons are produced when a particle meets its antiparticle. The energy of the photons is equal to the combined rest energy and kinetic energy of the particle and antiparticle, so energy is conserved.

• What about in regards to conserving matter itself? I'm guessing the particle distribution counts for conservation? Dec 9, 2019 at 19:23
• No, there is no law of conservation of matter. Baryon number and lepton numbers are conserved but because antibaryons have baryon number of -1 and antileptons have lepton number -1, creating or destroying a particle-antiparticle pair does not violate these conservation laws. Dec 9, 2019 at 19:34