Undergrad Inflation Models that don't produce Multiverse?

[cosmanino2050]

TL;DR

What are inflation models that don't produce multiverse?

What are inflation models that don't produce multiverse?

 

[weirdoguy]

What are inflation models that produce multiverse? What do you mean by multiverse? Any sources you are reading?

 

[cosmanino2050]

I

What are inflation models that produce multiverse? What do you mean by multiverse? Any sources you are reading?

I mean by multiverse these pocket or bubble universes which are produced during eternal inflation. I don't have a broad idea, but I think models like chaotic inflation or hybrid inflation do produce them.

 

[PAllen]

https://journals.aps.org/prd/abstract/10.1103/PhysRevD.27.2848

This paper is often cited as showing eternal inflation producing a multiverse is generic, and therefore inflation without this feature must be very special. As to a specific model known to be free of this, I don ‘t know - this is not something I know much about.

 

[Jaime Rudas]

What are inflation models that produce multiverse? What do you mean by multiverse? Any sources you are reading?

http://www.stanford.edu/~alinde/Eternal86.pdf

https://arxiv.org/abs/hep-th/0702178

 

[ohwilleke]

TL;DR Summary: What are inflation models that don't produce multiverse?

What are inflation models that don't produce multiverse?

In many models, the inflationary phase of the Universe's expansion lasts forever in at least some regions of the Universe. This occurs because inflating regions expand very rapidly, reproducing themselves. Unless the rate of decay to the non-inflating phase is sufficiently fast, new inflating regions are produced more rapidly than non-inflating regions. In such models, most of the volume of the Universe is continuously inflating at any given time.

All models of eternal inflation produce an infinite, hypothetical multiverse, typically a fractal. The multiverse theory has created significant dissension in the scientific community about the viability of the inflationary model.

From Wikipedia: Cosmic Inflation.

But, as the linked article discusses, there are all sorts of inflation models and "eternal inflation" to which this hypothesis applies, is only one of them. (Some time ago, I saw a catalog of inflation theories in a paper on arXiv that listed more than a hundred distinct variants of cosmic inflation theories, but I can't seem to find the link right now.)

Just reading the papers references by the others in this thread and this link, it appears that inflation models where inflation starts and then shortly after stops, as opposed to "eternal" inflation models, don't necessarily produce a multiverse.

As one example, "hybrid inflation" is not "eternal inflation", so it doesn't necessarily produce a multiverse.