[litehaus]

“Time does not exist for massless particles”

In that case, the word ‘particles’ describes what, if not matter ?

[Telepathic Intruder]

"In that case, the word ‘particles’ describes what, if not matter ?"

Matter and energy are both particle/waves, but fermions (matter) have mass while bosons (energy) do not. What separates them is that matter is subject to the Pauli exclusion principal while energy is not. And the root cause of this is supposedly the Higgs field. This is basic quantum physics, not that any of it is simple or easy to grasp. Feynman once said "If you think you understand quantum mechanics, you don't understand quantum mechanics".