Quantum gravity in astrophysics?

[romsofia]

I'm currently taking an astrophysics course, and need to do a project on some sort of on-going astrophysics research. Over the last year, I've been reading a few papers here and there in QG (specifically LQG), and was wondering if there was any on-going research relating quantum gravity in astrophysics??

Some problems I know of are fluctuations of the metric, but uh, don't know if that has ANY applicability in astrophysics as I'm pretty naive when it comes to this field.

Thanks for any help!

 

[marcus]

Ashtekar is a big name in QG (specifically LQG) and his focus is on the application of LQG to cosmology. He and two younger co-authors just came out with a major paper this month. It would have references to earlier related work.

http://arxiv.org/abs/1302.0254
The pre-inflationary dynamics of loop quantum cosmology: Confronting quantum gravity with observations
Ivan Agullo, Abhay Ashtekar, William Nelson
(Submitted on 1 Feb 2013)
Using techniques from loop quantum gravity, the standard theory of cosmological perturbations was recently generalized to encompass the Planck era. We now apply this framework to explore pre-inflationary dynamics. The framework enables us to isolate and resolve the true trans-Planckian difficulties, with interesting lessons both for theory and observations. Specifically, for a large class of initial conditions at the bounce, we are led to a self consistent extension of the inflationary paradigm over the 11 orders of magnitude in density and curvature, from the big bounce to the onset of slow roll. In addition, for a narrow window of initial conditions, there are departures from the standard paradigm, with novel effects ---such as a modification of the consistency relation between the ratio of the tensor to scalar power spectrum and the tensor spectral index, as well as a new source for non-Gaussianities--- which could extend the reach of cosmological observations to the deep Planck regime of the early universe.
64 pages, 15 figures

 

[marcus]

I was too busy and didn't get you a suitable bunch of suggestions. That paper may be too technical. I'll try to think how to get some papers relating QG and astrophysics which span a range of difficulty.

This list has some great papers but the link is slow. It might take 10 seconds. If it times out just click on it again.

It is a search specialized to find research that appeared 2009 or later exploring ways of TESTING quantum cosmology (phenomenology, comparing QG cosmology models with observation.)
http://www-library.desy.de/cgi-bin/spiface/find/hep/www?rawcmd=FIND+%28DK+LOOP+SPACE+AND+%28QUANTUM+GRAVITY+OR+QUANTUM+COSMOLOGY%29+%29+AND+%28GRAVITATIONAL+RADIATION+OR+PRIMORDIAL+OR+inflation+or+POWER+SPECTRUM+OR+COSMIC+BACKGROUND+RADIATION%29+AND+DATE%3E2008&FORMAT=www&SEQUENCE=citecount%28d%29
I just tested it and it took over 20 seconds but at least did not time out, and came up with 69 papers.
For example the top one on the list was:

1) Cosmological footprints of loop quantum gravity.
J. Grain, (APC, Paris & Paris, Inst. Astrophys.) , A. Barrau, (LPSC, Grenoble & IHES, Bures-sur-Yvette) . Feb 2009. (Published Feb 27, 2009). 7pp.
Published in Phys.Rev.Lett.102:081301,2009.
e-Print: http://arxiv.org/abs/0902.0145 [gr-qc]
TOPCITE = 50+
Cited 50 times
PhysRevLett.102.081301

Aurelien Barrau has written many papers relating QG to observational early universe cosmology, effects to look for in the CMB (microwave background, the most ancient light we can observe0
http://arxiv.org/find/gr-qc/1/au:+Barrau_A/0/1/0/all/0/1

Also Julien Grain has written a lot. You can look his up too. There are more recent papers than what i mentioned.

 

[romsofia]

Thanks for your help! I'll take a look at the papers you posted. And will also see what Julien Grain has written!

 

[pmacias]

Quantum gravity is a fascinating and complex area of research that has been gaining more attention in recent years. It aims to reconcile the theories of general relativity and quantum mechanics, which have been incredibly successful in their respective domains but are incompatible when it comes to the extreme conditions found in the universe, such as those in black holes or during the Big Bang.

In astrophysics, quantum gravity plays an important role in understanding the fundamental structure and behavior of the universe. One of the main areas of research in this field is the study of black holes, which are objects with such strong gravitational pull that even light cannot escape from them. General relativity predicts the existence of black holes, but quantum mechanics suggests that they should emit radiation and eventually evaporate. Understanding this process requires a deep understanding of quantum gravity.

Another area of research in which quantum gravity is relevant is the study of the early universe. The Big Bang theory, which is supported by a vast amount of evidence, describes the beginning of our universe as a singularity, a point of infinite density and curvature. However, this singularity is problematic from a theoretical perspective and may be resolved by incorporating quantum gravity principles.

In addition to these specific applications, quantum gravity also has a broader impact on astrophysics by providing a framework for understanding the fundamental laws of nature at the most extreme scales. It may also shed light on other mysteries of the universe, such as dark matter and dark energy.

As for the specific problem of fluctuations of the metric, this is indeed an important aspect of quantum gravity research. These fluctuations refer to the fluctuations in the fabric of space and time, which are predicted by quantum mechanics. Understanding these fluctuations is crucial for a complete understanding of the universe, and they have potential applications in astrophysics, such as in the study of gravitational waves.

In conclusion, quantum gravity is a rapidly evolving field with many ongoing research projects that have implications for astrophysics. It is a complex and challenging area of study, but it has the potential to greatly advance our understanding of the universe. I wish you the best of luck with your project, and I hope you continue to explore this fascinating topic in your studies.