Inflation without multiversion

[marcus]

Theorists have found it difficult to model inflation without having it run hog wild and produce a multiplicity of questionable scientific value. This has bothered Slava Mukhanov who calls it "selfreproduction" and considers it a problem. In September Mukhanov came out with this paper:
http://arxiv.org/abs/1409.2335
Inflation without Selfreproduction
Viatcheslav Mukhanov
(Submitted on 8 Sep 2014)
We find a rather unique extension of inflationary scenario which avoids selfreproduction and thus resolves the problems of multiverse, predictability and initial conditions. In this theory the amplitude of the cosmological perturbations is expressed entirely in terms of the total duration of inflation.
11 pages.
===quote 1409.2335 introduction page 1===
The recent CMB observations have unambiguously proven the theory of the quantum origin of the universe structure. According to this theory the initial quantum fluctuations were amplified in the very early universe and provided us with the seeds for galaxies [1], [2]. The simplest mechanism of amplification of these quantum fluctuations is realized in inflationary cosmology according to which the early universe went through the stage of accelerated expansion. On the other hand, the quantum fluctuations amplified during inflation also lead to selfreproduction and do not allow inflation to end up once it was started [6]. Inflation continues forever leading to a metaphysical (non-verifiable) concept of eternal universe and multiverse. According to [3], [4] the multiverse and eternal inflation damage the predictive power of the theory because in this case “anything can happen and will happen an infinite number of times” [5]. Moreover, the most favored by recent observations plateau-like potential returns us back the initial condition problem: “by favoring only plateau-like models, the Planck2013 data creates a serious new challenge for the inflationary paradigm: the universally accepted assumption about initial conditions no longer leads to inflation; instead, inflation can only begin to smooth the universe if the universe is unexpectedly smooth to begin with!” [3]. Raising these issues the authors of [3], [4] pose completely legitimate question whether the eternal multiverse inflation, which they call the “postmodern inflationary paradigm” as opposed to “classic inflationary paradigm”, does really allow us to explain anything and make any predictions? ...
The purpose of this paper is to find a natural extension of inflation to the Planck energy, which avoids the selfreproduction and initial condition problem and thus allows us to turn back to the “classic inflationary paradigm” with all its predictive power.
==endquote==

Today Sergei Odintsov posted a followup paper:
http://arxiv.org/abs/1412.2518
Inflation without self-reproduction in F(R) gravity
Shin'ichi Nojiri, Sergei D. Odintsov
(Submitted on 8 Dec 2014)
We investigate inflation in frames of two classes of F(R) gravity and check its consistency with Planck data. It is shown that F(R) inflation without self-reproduction may be constructed in close analogy with the corresponding scalar example proposed by Mukhanov for the resolution the problems of multiverse, predictability and initial conditions.
6 pages.
http://inspirehep.net/author/profile/S.D.Odintsov.1
http://inspirehep.net/author/profile/V.F.Mukhanov.1

 

[Drakkith]

Marcus, can you expand on what "selfreproduction" means? And how does inflation amplify quantum fluctuations?

 

[bapowell]

It appears that he is using "self-reproduction" to mean "eternal inflation". If you look back at Linde's original papers on the subject, that is the terminology that he employed (he called it the "eternally existing self-reproducing chaotic inflationary universe"...lots of adjectives!). The amplified quantum fluctuations to which Mukhanov refers are just the regular quantum variations in the field excursion of the inflaton.

 

[marcus]

Hi Brian, and Drakkith,
I somehow missed the question yesterday and just now saw both the Q and the A. Brian thanks for replying! I didn't know that Linde himself used that terminology from the start.

 

[Drakkith]

Thanks guys!

 

[Torbjorn_L]

Theorists have found it difficult to model inflation without having it run hog wild and produce a multiplicity of questionable scientific value.

I think it is questionable to claim that the open character of the low energy physics/cosmological constant is "of questionable scientific value". This trait of physics appears already with potentials, and we need to measure bias in order to pin down the universe (with a certain bias) that physics has chosen.

Except that here it is less open, if string theory is correct, with but a finite range of states as opposed to classical physics infinite range. That is progress, if fact.