Cosmology and inflation revisited

I hadn't noticed physicist Neil Turok before, but this lengthy interview with him posted recently on Youtube is really good.  Well, at least if you have some background idea as to the problems with physics advancement in the last few decades.

As many in comments say, he seems to have a particular knack for explaining some pretty complicated ideas in a (relatively) clear way:

 

His big thing explained near the start is that he was always skeptical of the ready adoption of early inflation of the universe amongst cosmologists; or perhaps to put it more accurately, that they accepted it without any great concern as to understanding how it could happen.  

I was happy to hear that, given that my feeling had been exactly the same for many years. 

Turok's recent proposal, which is still working on, is that there may be a "mirror universe" - and while this did get some publicity over the last few years, I think I didn't pay much attention because it sounded too much like a slightly wacky idea that New Scientist would run with once or twice and then it would never be heard of again.    But listening to him explain it, it sounds not so wacky.   And I think everyone would love that he believes it will be testable, and as he has before, he's more than happy to abandon ideas if they just don't pan out.

The only thing that is sort of disappointing (for those of us who like the weird idea of another universe, even if it is running backwards in time) is that Turok makes it clear that his mirror universe is not "real" - he says at one point that it only "real" in the same way everyday mirror images that we are familiar with are real.  As he says in a short-ish article that explains the idea:

But no, sorry, it wouldn’t be like the mirror universe in Star Trek. No one can transport to the other side to meet the mirror versions of Kirk and Spock with opposite personalities from their counterparts.

“I think of it more as a sort of mathematical device to do something sensible with the singularity. You have a picture of an extended spacetime and impose a symmetry on it, so you can flip it around,” Turok explains.

I also don't really understand what the implications of the idea are for the future of the universe - and also, whether it really explains why the universe's expansion seems to be increasing.

But in any case, he comes across as a particularly likeable physicist.

Finally, here's an article from the BBC from 2020 which talks about the mirror universe idea, as well as Penrose's proposal for a cyclical universe (which seems not to have caught on at all.)