It's official. The universe is dying.

[BrianSoddingBoru4]

But where does all the energy go?

It doesn't really 'go' anywhere, in reference to the universe as a whole. The energy contained in and produced by a star is still there when that star goes nova or supernova, it's just spread out across a much bigger area.

Imagine you've got a bucket of sand (don't we all) and you decide to scatter that sand across an area of a thousand square miles (like people do). The sand isn't 'gone' in any meaningful sense. It's still there, just harder to find and no longer contained in a bucket.

Boru

addendum: I call upon the actual science people on this board to tell me how bad that analogy is. Thank you.