- #1
Jack2013
- 13
- 0
Can string theory or quantum gravity theory predict faster than light neutrinos ?
Last edited:
atyy said:An attempt: http://arxiv.org/abs/1109.5687
MathematicalPhysicist said:They publish articles faster than mushrooms spreading on a tree.
Jack2013 said:Can string theory or quantum gravity theory predict faster than light neutrinos ?
If so, then why string theorists do not like loop quantum gravity, which is also predicted by string theory?unusualname said:Of course it can, ST can predict everything
Haelfix said:Every theorist in the world has tried to come up with a method to make the Opera result work, and had to revisit basic assumptions about the nature of reality. This is quite fun, even though it is a completely tortured process, whereby the theorist has to bend over backwards.
If you actually had read the paper, you would know that embedding/UV completing such an extra dimension model (the EFT) into String theory is extremely difficult, b/c it violates the Null Energy condition. Read, it just doesn't seem to work.
Many of us have come to similar conclusion for different but related reasons, even at the level of the effective field theories. You either have to introduce an enormous amount of finetuning, and a whole superstructure to enforce that things work out properly, or you run afoul of basic experimental facts and start having theoretical breakdowns.
(I wrote down a model that ended up having an unstable vacuum at 3 GeV to give you an idea of the sorts of issues). The fun fact that you end up learning is that exact Lorentz invariance and universal couplings really protects you from disaster in hundreds of different ways.
One of the many fundamental problems any such theory faces is that neutrinos and leptons are linked, and so explaining why one doesn't feel the effect, and the other does, invariably leads you to write down a new model for electroweak symmetry breaking. This is bad, b/c we already know a lot about that, and the constraints are more or less extreme.
Haelfix said:Every theorist in the world has tried to come up with a method to make the Opera result work, and had to revisit basic assumptions about the nature of reality. This is quite fun, even though it is a completely tortured process, whereby the theorist has to bend over backwards.
If you actually had read the paper, you would know that embedding/UV completing such an extra dimension model (the EFT) into String theory is extremely difficult, b/c it violates the Null Energy condition. Read, it just doesn't seem to work.
Many of us have come to similar conclusion for different but related reasons, even at the level of the effective field theories. You either have to introduce an enormous amount of finetuning, and a whole superstructure to enforce that things work out properly, or you run afoul of basic experimental facts and start having theoretical breakdowns.
(I wrote down a model that ended up having an unstable vacuum at 3 GeV to give you an idea of the sorts of issues). The fun fact that you end up learning is that exact Lorentz invariance and universal couplings really protects you from disaster in hundreds of different ways.
One of the many fundamental problems any such theory faces is that neutrinos and leptons are linked, and so explaining why one doesn't feel the effect, and the other does, invariably leads you to write down a new model for electroweak symmetry breaking. This is bad, b/c we already know a lot about that, and the constraints are more or less extreme.
Haelfix said:Again, the fundamental problem with most types of Opera ideas is twofold
1) You need to have a very sharp energy dependence in the dispersion relationships to explain the Supernovae measurement. This is doable in the extra dimension models, whereby only past a certain scale do the neutrino's 'feel' the extra metric structure.
2) You need to explain why in the standard model, each family of lepton doublets (say the electron and the electron neutrino) do NOT react similarly to the changing geometry. This is the key point where most ideas hit a wall (and not so much in the actual spontaneous breaking of Lorentz invariance perse). Simply put, we know the electron doesn't move past the speed of light with extreme precision. So you need to explain this experimental asymmetry somehow. Of course this goes right to the heart of electroweak symmetry breaking, and really requires changing the universality of the couplings. This is where problems lurk for those aforementioned papers, whether for string theory or really any phenomenology...
marcus said:...
But his [Weiler's] interests seem closely tied to what can be found out using LHC and what immediate changes in Standard Model might result. He does not seem, from his 26 co-authored papers, to be in any sense a string theorist.
Ooops! The Weiler in question is TOM Weiler at Vanderbilt U. in Tennessee. Not Andreas.Haelfix said:Actually I don't agree with Andreas. I don't see any consistent theory or explanation of the data at the moment other than the rejection of the hypothesis. Not from string theory, not from effective field theory, not from anywhere...
Haelfix said:2) You need to explain why in the standard model, each family of lepton doublets (say the electron and the electron neutrino) do NOT react similarly to the changing geometry. This is the key point where most ideas hit a wall (and not so much in the actual spontaneous breaking of Lorentz invariance perse). Simply put, we know the electron doesn't move past the speed of light with extreme precision. So you need to explain this experimental asymmetry somehow. Of course this goes right to the heart of electroweak symmetry breaking, and really requires changing the universality of the couplings. This is where problems lurk for those aforementioned papers, whether for string theory or really any phenomenology.
atyy said:What are the constraints like on muons compared to electrons? Are those less tight? Could you make just the muon and muon neutrino break light speed, but not the electron and electron neutrino?
czes said:Are there phenomennos which can not be predicted by String Theory ?
marcus said:The question is "can string predict FTL neutrinos?". this paper co-authored by Dmitri Nanopoulos would indicate that it can.
http://arxiv.org/abs/1110.0451
Background Dependent Lorentz Violation from String Theory
Tianjun Li, Dimitri V. Nanopoulos
(Submitted on 3 Oct 2011)
We revisit Lorentz violations in the Type IIB string theory with D3-branes and D7-branes. We study the relativistic particle velosities in details, and show that there exist both subluminal and superluminal particle propagations. In particular, the additional contributions to the particle velosity [tex]\delta v\equiv (v-c)/c [/tex] from string theory is proportional to both the particle energy and the D3-brane number density, and is inversely proportional to the string scale. Thus, we can realize the background dependent Lorentz violation naturally by varying the D3-brane number density in space time. To explain the superluminal neutrino propagations in the OPERA and MINOS experiments, we obtain the string scale should be around 10^5 GeV. With very tiny D3-brane number density at the interstellar scale, we can also explain the time delays for the high energy photons compared to the low energy photons in the MAGIC, HESS, and FERMI experiments simultaneously. Interestingly, we can automatically satisfy all the stringent constraints from the synchrotron radiation of the Crab Nebula, the SN1987a observations on neutrinos, and the cosmic ray experiments on charged leptons. We also address the possible phenomenological challenges to our models from the relevant experiments done on the Earth.
14 pages, 1 figure
So the straightforward answer is clearly yes it can predict FTL. (and also not.)
I do not mean to suggest that the theory is right or has some connection with nature. Those are separate questions. It may be impossible for a correct theory to predict FTL. I'm not giving an opinion on that. I just point out that D.N. is a prominent string guy and he shows how to get string to predict various stuff so as to agree with these various observational/experimental results.
String theory is a theoretical framework that attempts to reconcile quantum mechanics and general relativity by describing the fundamental building blocks of the universe as tiny strings rather than point-like particles.
Currently, string theory does not have the capability to predict the behavior of neutrinos. It is a complex and ongoing area of research, and while some theories within string theory suggest the possibility of faster than light particles, there is no consensus on whether this is possible or not.
If proven true, the existence of faster than light neutrinos would challenge our current understanding of the laws of physics, particularly Einstein's theory of relativity. It could also potentially have significant implications for space travel and our understanding of the universe.
In 2011, the OPERA experiment at CERN reported observing neutrinos traveling faster than the speed of light. However, this result was later found to be due to faulty equipment and the experiment could not be replicated. As of now, there is no solid evidence for the existence of faster than light neutrinos.
String theory is a highly complex and abstract theory that is still in its early stages of development. It has not yet been experimentally verified, and there are many different versions of the theory, making it difficult to test. Additionally, it has not yet been able to fully explain all aspects of the universe, such as the behavior of particles like neutrinos.