2 ms·
My very limited understanding of the topic is that for a gravitationally bound system like the Earth, the usual rules apply, but on cosmological scales the expa
by pezezin 2y ago
My very limited understanding of the topic is that for a gravitationally bound system like the Earth, the usual rules apply, but on cosmological scales the expansion of the universe means that time-translation is not invariant and thus conservation of energy is not well-defined.
https://en.wikipedia.org/wiki/Conservation_of_energy#General_relativity https://en.wikipedia.org/wiki/Conservation_of_energy#General...
- jmward01 2y agoGetting rid of the time side then, think of it as an orbit. If the universe was expanding then something could be orbiting slower than gravity would allow. Basically this question keeps bringing me back to the ties between mass and the expansion of the universe. No matter how you look at it mass must be special when it comes to expansion because it is either giving off 'free' energy in the form of slow orbits and acceleration between two objects or it -isn't- giving off that energy and something is canceling it out. Following this rabbit-hole is pretty interesting at a minimum.