pakarinen wrote: ↑Thu Feb 08, 2024 5:32 pm
Interesting paper...
Is it? Did you read the whole thing? Somehow, I don't think so, otherwise, you would have realised that this is about the Hubble constant. There is no concrete evidence to suggest that the Hubble constant and dark energy are indeed the same thing. They could be, but we won't know how closely they are related and if they are the same thing until we get the results of the latest full data sets from the most recent experiments, which are still in progress. The authors are quite careful about that.
Ultimately, the Hubble tension is a motivating factor for this paper which attempts to address the issues associated with the two measured values for the Hubble constant by invoking the idea of bombardment by baby iniverses. However, as the authors of the paper state, there are caveats. Some of these are quite important to consider before one states that something is or is not required. For example...
First and perhaps the most difficult one to swallow is the fact that they address a real measured problem in the observable universe with something that is ultimately pure speculation and hypothetical.
As stated, the models used are quite primitive and unrealistic
They apply to late-time evolution and say nothing about the early evolution of the universe, except where the authors speculate that our universe could have been absorbed by a larger universe, thus doing away with the need for an inflation field and associated inflaton. They then go on to say that they have no process for this and it's difficult to say if this is even possible and might not even do away with the need for inflation.
Different model modes are required to deal with the different measured Hubble parameters requiring a best-fit scenario.
These 'possibilities' are all modelled in 'minispace' environments and they are not sure how this would all play out in the real world.
Thus, while it is an interesting idea, and it genuinely is. It merely hints at the possibility of an alternative view that might hold credence, if it were possible to prove that our universe has indeed been bombarded by baby universes.
It does nothing to prove that we don't need dark energy. It shows an expanding universe that doesn't require a Hubble constant. So dark energy is merely replaced with baby universe collisions that squash the Hubble Constant yet still provide expansion. In other words, dark energy is still required to get the universe we live in. Just a different phrasing.
Our current best-fit model still stands, for now.