If mass is not conserved but instead energy is conserved, is it right to say that the fundamental particles are photons?

Question

If mass is not conserved but instead energy is conserved, so is it right to say that the fundamental particle of the Universe is photon instead of protons, neutrons, electrons, leptons, etc and all that. That is all mass is eventually made of photons (energy).

Or another form of this question would be What can one imagine the entire universe to be made up of? Well in Greeks time they thought it to be atoms. But I want a answer synchronous with today's information. Please try to add a simplified version of quantum mechanics.

Or simply Please connect energy to mass taking in consideration the fact of sub atomic particles.

Answer 1

You are making the mistake of thinking that photons are energy while massive particles are not. Photons are just a particle, albeit a massless one. There are other massless particles, for example gluons, and indeed at energies above the electroweak phase transition all fundamental particles are massless. So the distinction you are making between photons and other particles is a false one.

Our current description of particles is that they are excitations of quantum fields, and it is the quantum fields that are fundamental not the particles. Every particle has its associated quantum field, so there is a photon field, an electron field, quark fields and so on. When you add a quantum of energy to a quantum field it creates a new particle, and you can destroy a particle by removing a quantum of energy from a quantum field. Particle reactions, for example the creation of Higgs bosons at the LHC, happen when energy is transferred between quantum fields.

So actually all particles are basically energy in the sense that they were created by adding energy to a quantum field. This applies whether you're creating a photon, an electron, a quark or whatever.

Answer 2

If mass is not conserved

This statement needs a qualification. In our everyday life, mass is conserved. Even banks weigh coins of the same denomination to know how many coins there are in the vault. In the framework where classical mechanics works, mass is conserved.

but instead energy is conserved,

It is in special relativity that mass and energy are correlated.

For a complex of particles, their invariant mass is not equal to the sum of their masses, in contrast to the classical regime where the mass of objects is additive.

so is it right to say that the fundamental particle of the Universe is photon

The photon is a part of the elementary particles of the standard model of physics.

They are called elementary because they are not composed out of other particles.

instead of protons, neutrons,

True, protons and neutrons are composite. They each are composed of quarks, elementary particles in the table.

electrons, leptons, etc and all that.

All the particles in the table are elementary, as elementary as the photon.

That is all mass is eventually made of photons (energy).

The above is a blanket statement. At the energies of our laboratories each particle is fundamental, not only the photon, and has a definitive role in building up macroscopic matter. It is only when modeling the beginning of the universe where one can talk of all matter being energy, but that is another story and needs quantum mechanics and General Relativity . These are combined in the Big Bang Model , and there you will see that the photons appear at the same time as the rest of the particles in the table.

Answer 3

Both energy and mass are conserved in a closed system. For example, if you have a box with reflective inside walls, and you fill it with light, the light will contribute to the rest mass of the box. If you then convert that light to matter (keeping the box closed), the rest mass will not change. The photon pressure adds the same inertia and weight to the box as the corresponding particles (if the light were converted to particles) would. Note that the stress-energy tensor does not add 'extra' mass to a system. Rather, it simply accounts for the extra energy found in the stress of the system that we might otherwise would have naively neglected. That stress represents real energy that can be converted to other forms, like particles or light.