Dark energy not needed?
Posted: Sat Jan 25, 2020 10:36 am
Einstein’s general relativity doesn't have gravity carried by particles. Quantum theories of gravity have gravity carried by particles (like quantum theories of electromagnetism have the photon) but nobody has a working quantum theory of gravity. So, first you would need one of those, and then you give your gravity-carrying spin-2 boson a tiny non-zero mass. Her list of publications is here but even I'm not theoretical enough of a physicist to read it all now on a Saturday morning and form an opinion. But it can at least be said to be a mathematically consistent theory. Whether it has any bearing on reality is a completely different question.The theory, known as massive gravity, modifies Einstein’s general relativity, positing that the hypothetical particles (gravitons) that mediate the gravitational force themselves have a mass. In Einstein’s version, gravitons are assumed to be massless.
Also, not everyone is entirely convinced that the rate of the expansion of the universe is actually accelerating which is the result which dark energy is supposed to "explain" (i.e. something is happening which you don't understand so you invent something which you don't understand to take care of it). In that case, however, I think that the expansion of the universe is actually accelerating.
Any mass of the graviton would have to be really tiny since gravity still works over very long length scales. This is probably going to be one of those parameters which will be forever set at just too small to actually measure.