/sci/ - Science & Math

>>6919460
You are kind of misunderstanding it. see >>6919527

In GR, if I straight up wanted to use the quantity we usually call "energy" it wouldn't be helpful at all. It is not conserved and gives no meaningful insight into anything.

However, we can find other quantities that are useful. We could get this "energy-analog" thing (sometimes just called energy). However, even the "energy-analog" is not necessarily conserved either. It is decreasing in a expanding universe, increasing in a contacting universe, and constant (conserved) in a static universe.

Why? Because in a expanding/contacting universe, the global time symmetry is all fucked up. The universe is "changing size" as a function of "time", which destroys the symmetry.