AMA | October 2024

2197.435 - 2219.699 Sean Carroll

the word energy has different definitions in different contexts, okay? So general relativity as a theory is completely time translation invariant. There's no special time in the universe according to general relativity. Therefore, by Neurodress theorem, there should be a conserved quantity, and there is. There is a conserved quantity that you can call the energy of the universe.