Matter and energy are coexisting and self-existing, indestructible and immortal.

Atom is an AC generator. The charged particles within an atom are indestructible. The attraction force between the positively charged nucleus and negatively charged atom ball and the repulsion forces between negatively charged particles are indestructible, therefore atom's formation energy is immortal. All atoms are constant oscillation/vibrating, therefore energy in the universe is conserved.

Energy is the motive force matter carried. Moving matter/mass carries kinetic energy 1/2MV^2. Resting matter/mass carries electric energy/heat/alternating current/chemical energy/nuclear energy.

The more atoms get together due to gravity, the more mass attracts together, the stronger gravity it has, the higher temperature it will be. Bigger stars are hotter/brighter/denser. Hotter matter carries higher voltage AC within atoms and atoms oscillate at a higher frequency.

The energy radiate out from matters' surfaces are in the form of inducing alternating current between distant matters, therefore radiant energy density is decay at 1/R^2. The energy transfers between contact matters/conduction heat transfer are in the form of alternating current, therefore heat is always moving from higher temperature matter to lower temperature matter.