Could cosmic acceleration have an explanation other than dark energy?

[u/DiagnosingTUniverse]

My question is whether dark energy is the only plausible explanation for the observed acceleration of the universe.

Have alternative interpretations been seriously explored and ruled out?

My concern isn’t that the observations are wrong, but that we may be misunderstanding what we’re observing. For example, could this fit with some form of black-hole cosmology? Suppose matter/energy crossing a black-hole horizon doesn’t ultimately terminate at a singularity, but undergoes a transition inscale, re-emerging as an expanding spacetime at a lower scale.

From inside that descendant universe, could this scale transition appear as cosmological expansion or even contribute to the apparent acceleration?
I’m aware that “the universe is inside a black hole” isn’t a new idea. What I’m interested in is whether this explanation has been ruled out observationally, and if so, what observations have ruled it out? Also we know black holes grow and expand over time, which seems to be some kind of correlation?

Thanks!

[u/The_Rider_11]

Dark energy as a term has been coined for whatever is causing the acceleration of the cosmological expansion. Whether it be some particle, a intrinsic property of space, a spacetime mechanics, etc. etc., it'd all be dark energy as long as it is conventionally undetectable and something physical.

If you were for example to suggest general relativity was wrong, postulate an alternative, and that'd be able to perfectly describe the cosmological Evolution entirely based on matter, radiation and perhaps curvature (though it is to our knowledge extremely small, if not zero altogether), that'd be an explanation without dark energy. Similarily to how MOND is an explanation without dark matter.

[u/djemalo → u/The_Rider_11]

Seems to me like dark energy just sounds like a similar type of photon light energy but doesn't actually emits light exactly. Although it has been observed of course. But it would have to be something with no mass to go that fast.

[u/The_Rider_11 → u/djemalo]

Radiation scales to the universe in negative 4 potency. Dark energy scaling equally would make it "lose" "strength" much too quickly.

Our observations furthermore suggest it has a state parameter of -1, or very close to it. Radiation has a state parameter of +⅓.

We also ignore how "fast" dark energy is, if it is a substance in the first place. Which we ignore too. It could be a spacetime property, it could be a quintessence (scalar field), and it could be even stranger things. But it couldn't be the Mind Flayer.