Energy and the end of the universe.

[mee]

If energy can neither be created or destroyed, why is there supposedly a "heat death" or any sort of death to the universe.

[selfAdjoint]

Energy can be free or not. If it's free it can do things, if it's not the only thing it can do is make heat. If the heat is the same temperature everywhere, nothing physical can happen on the larger scale. Entropy is the conversion of free energy into heat energy. The energy is not destroyed but its ability to effect change is no more.

This is now seen as a statistical effect, of the more probable states succeeding the less probable ones. And there could always be a quantum fluctuation, so the heat death is not the ultimate last thing the nineteenth century physicists envisioned.

[mee]

Energy can be free or not. If it's free it can do things, if it's not the only thing it can do is make heat. If the heat is the same temperature everywhere, nothing physical can happen on the larger scale. Entropy is the conversion of free energy into heat energy. The energy is not destroyed but its ability to effect change is no more.

This is now seen as a statistical effect, of the more probable states succeeding the less probable ones. And there could always be a quantum fluctuation, so the heat death is not the ultimate last thing the nineteenth century physicists envisioned.

I assume by non free energy you mean matter and by heat you mean fusion or like in the earths core perhaps. Does heat not mean like in the cores of stars? Would this heat not effect change like fusion? Will there perhaps be a universe which is full of higher elements with new types of structures we currently dont understand coming into being? Are you basically telling me that "heat death" of the universe is an outdated concept?

[selfAdjoint]

No, by not free I mean energy confined to jiggling, with no temperature differential anywhere. Matter is unstable on the longest scale (protons eventually decay even in the standard model), so that eventually we are talking about a bath of photons at equilibrium.

[mee]

No, by not free I mean energy confined to jiggling, with no temperature differential anywhere. Matter is unstable on the longest scale (protons eventually decay even in the standard model), so that eventually we are talking about a bath of photons at equilibrium.

But we have never actually detected a proton decay right?