Researchers claim to have found serious fault with the existence of dark energy, but not everyone is buying into it.
Has Dark Energy Been Debunked? Probably Not. : Read more
"a universe without dark energy would have a lot of structure " - it would have little to no structure as the "energy' is just the flip side of what they're calling dark matter and without such the matter in the universe would just collapse into a singularity again.
We just might need new physics to get out of this mess.
Space is no longer smooth, it's lumpy now, so Hubble will not be a constant. The ironic part is they're using gravitational lensing, which is non-constant space to try and prove a constant. What needs to be examined is if gravity is the deformation of time-space itself or another force that's affected by the deformation. Another point, does gravity act linearly through space-time or does it act through the foreshortened distortion in space time? This could account for the missing dark matter aspect by itself.
We know that space-time is expanding, attributing it to an independent energy is likely a mistake, we look at gravity as a force of attraction, why wouldn't time-space itself be the balancing force of repulsion and the gravity we observe the leftover?
For what's being discussed, whether space-time is an "aether", field or particles is immaterial as these include assumed properties, just the actions and reactions are necessary. Enough properties are collected and then the greater characteristics of space-time may be hypothesized, it may not match any of these.
One of things we know is that space-time is positively affected by gravity from the lensing. Given the speed of light is a hard limit for space-time and extra energy is changed to mass, we can deduce that it has a negative affinity for energy. So how much do those high energy particles "push" space-time to expand?
Space-time deforms with mass and may cause gravity, if the deformation causes gravity it would be instantaneous, if it's deformed by gravity instead of mass itself that leaves room for a rebound to the distortion. The reason I bring this up is photon time travel, where a photon triggers both paths but only finishes one, could be an indication of time-space rebound.