APS Physics view of pre-inflation cosmology article

[marcus]

"APS Physics" view of pre-inflation cosmology article

The APS has an online periodical that publishes "Viewpoints" on current research, for instance http://physics.aps.org/articles/v5/142
is an interpretive explanatory viewpoint, written for non-specialists,
on the article by Agullo Ashtekar Nelson published last month in Physical Review Letters.

This is on geometry&matter fluctuations in the PRE-INFLATION era. Basically it extends the conventional inflation analysis back further in time, where the conventional analysis is not valid because it is set on a (singular) classical space-time.

There is also a write-up of the Agullo et al work in the January 2013 SciAm
by Davide Castelvecchi.

Here's the PRL article (they made it a "featured article" with free access)
http://physics.aps.org/featured-article-pdf/10.1103/PhysRevLett.109.251301
It is also available on arxiv, along with a 50 page paper giving technical detail on which the PRL Letter is based.
short PRL article preprint: http://arxiv.org/abs/1209.1609
50 page article: http://arxiv.org/abs/1211.1354
==quote 1211.1354==
An Extension of the Quantum Theory of Cosmological Perturbations to the Planck Era
Ivan Agullo, Abhay Ashtekar, William Nelson
(Submitted on 6 Nov 2012)
Cosmological perturbations are generally described by quantum fields on (curved but) classical space-times. While this strategy has a large domain of validity, it can not be justified in the quantum gravity era where curvature and matter densities are of Planck scale. Using techniques from loop quantum gravity, the standard theory of cosmological perturbations is extended to overcome this limitation. The new framework sharpens conceptual issues by distinguishing between the true and apparent trans-Planckian difficulties and provides sufficient conditions under which the true difficulties can be overcome within a quantum gravity theory. In a companion paper, this framework is applied to the standard inflationary model, with interesting implications to theory as well as observations.
Comments: 50 pages, no figures. This is first of the two detailed papers on which arXiv 1209.1609 (PRL at press) is based
==endquote==

It's nice to see pre-inflation cosmology becoming increasingly visible in science media.

In case anyone wants, here's the SciAm link:
http://www.scientificamerican.com/a...-einsteins-relativity-universes-first-moments

 

[AndyW]

Dear forum members,

I am a scientist with a background in cosmology and I would like to share my insights on the recent APS Physics article on pre-inflation cosmology.

First of all, I would like to commend the APS for featuring this article and making it freely accessible to the public. It is important for the general public to have access to current research in physics, especially in a field as complex and fascinating as cosmology.

The article discusses the work of Agullo, Ashtekar, and Nelson, who have extended the standard theory of cosmological perturbations to the pre-inflation era using techniques from loop quantum gravity. This is a significant development in our understanding of the early universe, as it allows us to overcome the limitations of the conventional inflation analysis, which is only valid on a classical space-time.

One of the key implications of this work is the distinction between true and apparent trans-Planckian difficulties in the pre-inflation era. This is an important conceptual issue that has been addressed in this new framework, providing a more robust understanding of the early universe.

The article also mentions a companion paper, which applies this framework to the standard inflationary model. This has interesting implications for both theory and observations, and I would encourage interested readers to also look into this paper for a deeper understanding of the topic.

In addition, the SciAm article by Davide Castelvecchi provides a great overview of the work and its significance. I highly recommend reading it for a more accessible explanation of the research.

Overall, I am excited to see pre-inflation cosmology gaining more attention in the scientific community and in the media. It is a rapidly developing field and I look forward to seeing more advancements in our understanding of the early universe.

Thank you for reading and I welcome any further discussion on this topic.