Protons, which are stable subatomic particles found in the nucleus of atoms, do not "burn" in the traditional sense. Burning typically refers to a chemical reaction that involves the combination of a fuel with oxygen, producing heat and light as byproducts. However, protons do not undergo such reactions.
In terms of stability, protons are considered to be fundamentally stable particles. They are not expected to decay or transform into other particles under normal circumstances. The stability of protons is a result of certain fundamental properties of the universe, such as the conservation of electric charge.
That being said, there are speculative theories and hypothetical scenarios where protons might undergo decay, but these are beyond the current understanding and knowledge of particle physics. In such scenarios, protons could potentially decay into other particles, but they would not "burn" in the conventional sense.
It's important to note that the concept of eternity is a philosophical and metaphysical concept that goes beyond the scope of scientific understanding. The stability of protons is based on our current understanding of physics, but as scientific knowledge advances, our understanding of fundamental particles and their behaviors may evolve.