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So whose quantum gravity theory will crash-and-burn if this is correct?
http://physicsworld.com/cws/article/news/40834
Zz.
http://physicsworld.com/cws/article/news/40834
Zz.
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He also points out that his group's approach probes just one of a number of possible effects of Lorentz invariance violation, and that extremely precise constraints on this violation have been obtained by studying the possible dependence of light speed on photon polarization from X-rays emitted by the Crab nebula.
ZapperZ said:So whose quantum gravity theory will crash-and-burn if this is correct?
MTd2 said:It also doesn't rule out varying speed of light theories whose first order correction is quadratic in the speed of light.
This very discussion on the 31GeV photon appeared in several blogs and even here a few months ago due to a preprint that showed on the arxiv.org. I thought that preprints to Nature articles were embargoed at least until the day of their publication. So, it's weird that this article showed up in Nature.
ZapperZ said:No, that's a myth.
Nature doesn't embargo preprints appearing, even in ArXiv. But you run the risk of some news media picking it up, and when that occurs, then the fact that it has been covered in another media will cause it to be disqualified from Nature and Science.
See this thread:
https://www.physicsforums.com/showthread.php?t=325116
Zz.
ZapperZ said:So whose quantum gravity theory will crash-and-burn if this is correct?
http://physicsworld.com/cws/article/news/40834
Zz.
atyy said:Yours! (I believe you're rooting for condensed matter? ) AdS/CFT will still survive, if you consider that condensed matter. These guys are still trying to get realistic cosmologies out of it http://arxiv.org/abs/0908.0756 .
atyy said:The link http://www.nature.com/authors/editorial_policies/embargo.html you gave on the other thread seems to say that it is not a problem if other media pick it up from arXiv - it's only a problem if authors discuss it with other media.
In fact, this article was picked up by other media from arXiv before publication in Nature:
http://motls.blogspot.com/2009/08/fermi-kills-all-lorentz-violating.html
http://backreaction.blogspot.com/2009/08/that-photon-from-grb090510.html
http://egregium.wordpress.com/2009/08/17/news-from-fermi-formerly-glast/[/URL][/QUOTE]
Those are bloggers, not the media. The embargo policy does not prohibit academic exchange or discussion of the paper. I've had a long discussion with one of Nature's associate editor a while back asking for clarification of this policy, and what I've stated is what I've understood based on not only their stated policy, but also from that discussion.
You should also factor in the DATE that the manuscript was accepted for publication, and when it appeared on ArXiv. Many authors who submitted their work to Science or Nature will upload the manuscript AFTER receiving acceptance. I know that we did that.
Zz.
I know there are specific models which do so, but from the onset those are working hypothesis to see what comes out, not really "postulates". The way I see it, the hypothesis is used to shortcut the time necessary to decide whether Lorentz violations are predicted to happen as breaking of the symmetry from the postulates themselves.</mood>certain theories of quantum gravity that postulate the violation of Lorentz invariance.
tom.stoer said:Some months ago I asked regarding the current status of nnon-trivial dispersion relation in LQG / SF theories. A couple of years ago these theories seemed to propose
- non-trivial dispersion relations, related to DSR in some semiclassical limit
- perhaps GZK violation
- polarization effects in CBR
These predictions depend on the semiclassical state which is still not known and therefore everything was speculative. I haven't seen any new or updated paper regarding these subjects for months (or even years), neither on arxiv nor in any journal.
So what is the current status of these theories?
...
tom.stoer said:So what is the current status of these theories?
If their predictions are negative (which would agree with the above mentioned experiment): do these theories run into the same problem as string theory, namely to make post-dictions only?
You mentioned dispersion, energy-dependent speed of signal propagation. I think you are right that there has been substantially no interest in that for several years in the loop/foam research community as a whole. A number of people worked on it around 2005-2006 but couldn't get any clear predictions.
Lorentz invariance is a fundamental principle in physics that states that the laws of physics should remain the same for all observers in uniform motion. It is important because it forms the basis for Einstein's theory of special relativity and helps us understand the behavior of objects moving at high speeds.
Lorentz invariance has been verified through a variety of experiments, including the Michelson-Morley experiment, which showed that the speed of light is the same for all observers, regardless of their relative motion. Additionally, particle accelerators have confirmed that the laws of physics hold true at high energies and speeds, as predicted by special relativity.
The Planck scale is the scale at which quantum effects become important and classical physics breaks down. It is significant in relation to Lorentz invariance because it is the highest energy scale at which we can test the principles of special relativity and determine if they hold true even at the smallest scales.
Recent experiments, such as the observation of high-energy cosmic rays, have shown that the laws of physics, including Lorentz invariance, hold true at extremely high energies. Additionally, some theories, such as string theory, predict that Lorentz invariance is a fundamental symmetry of the universe at all energy scales.
Lorentz invariance is a fundamental principle that has helped shape our understanding of the universe, particularly in the fields of special and general relativity. It has also played a crucial role in the development of modern theories, such as the Standard Model of particle physics, which relies on the principles of Lorentz invariance. Without it, our understanding of the behavior of matter and energy at high speeds would be incomplete.