Multiple (Non-Interacting) Universes?
Before anything, I would like to clarify that I am aware that this is speculative physics more than established mainstream physics (and <PERSON> is not claiming that his ideas are true). However I think that it is interesting to discuss these models even if they are not yet proven to be right.
I was reading an interesting paper by Nobel laureate Mr. <PERSON> (https://arxiv.org/abs/1003.5952) where he assumes the holographic principle as true and conjectures that our universe would be encoded on the "surface" of an apparent horizon as the weighted average of all possible histories. In that way, there would be one world (or universe) that would be the average among all possible worlds.
However, I was not sure if <PERSON> refers to our Universe is the actual one in the sense that this is the one that we observe while the other histories would exist as (unobserved) different worlds (like in the Many Worlds Interpretation), so I sent him an email. 484
After some time he replied. However I'm not still sure of what he means. Could you help me understand what he said:
I sent him:
(...) Couldn't there be other apparent horizons, and therefore, other universes that are the result of the average of all possible histories in those horizons? And also, in your model, could there be any situation where the other histories would be considered as real (similar to the many worlds interpretation) instead of only one being real?
And he basically replied that his view does hold that many different versions of the Universe coexist with very different weightings and that it is likely one is in a version with high weighting and it is likely most of the high weightings are similar. He added that, however, they are forbidden to communicate and interact just like things outside the horizon: If they communicated and interacted, then they would be part of the same Universe version.
Does it sound like he meant that other universes would exist and would be real but they could neither interact nor communicate? 283