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Gamma Ray Anomaly Could Test String Theory

Posted by kdawson on from the finally-experimental-data dept.

exploder writes "String theory is notorious for its lack of testable predictions. But if the MAGIC gamma-ray telescope team's interpretation is correct, then a delay in the arrival of higher-energy gamma rays could point to a breakdown of relativity theory. A type of 'quantum lensing effect' is postulated to cause the delay, which is approximately four minutes over a half-billion year journey." Ars's writeup is a little more fleshed-out than the Scientific American blog posting.

4 of 128 comments (clear)

  1. Not specific to String Theory by E++99 · · Score: 5, Informative

    While this is great research, even if it can be demonstrated that the higher energy particles traveled faster, this is not a prediction specific to String Theories, but as the arstechnica.com article points out, this is common to most quantum gravity theories. Still, it would be an awesome thing to prove.

    1. Re:Not specific to String Theory by hedwards · · Score: 5, Insightful

      I think that it is definitely important to note, as you did, that this isn't just a matter for string theorists.

      I really wish that string theory wouldn't be glorified the way that it is. I am not aware of a single hypothesis that has been successfully tested and validated under it. And as you mentioned, string theory does predict something like this, but so do other forms of physics.

      This is definitely a significant finding, because gamma rays should be traveling at the speed of light, and only that speed through a vacuum. I read through things quickly, but it doesn't appear that any reasoning was advanced in the article for the delay. But as long as the rays left at the same time, this would be a problem for relativistic physics. Unless it turns out that there is some sort of mass in the medium, in which case the relativity is still fine.

  2. Relativity's Dead by einsteindotcubed · · Score: 5, Informative

    There is no need to confirm a breakdown of relativity. We already know that it is, at the least, incomplete, if not incorrect. Albert Einstein himself saw this, and was on his own quest for a "theory of everything" in his later years. String theory should become fully "testable" with the startup of the LHC (Large Hadron Collider, part of CERN) in May of 2008. Hopefully we may find proof for the God particle, also known as the Higgs boson. In any case, tremendous amounts of data will be reaped from this machine, and we may very well prove or at least expand upon string theory. (We could also completely disprove it, but I'm trying to be optimistic.)

    --
    I do know everything, just not all at once. It's a virtual memory problem.
  3. Important caveat by jlkelley · · Score: 5, Insightful

    IAAA [I am an astrophysicist], and I'd like to point out what I feel is an important caveat to this nevertheless very interesting work. From the paper itself:

          "We cannot exclude the possibility that the delay we find [...] may be due to some energy-dependent effect at the source."

    What they are saying is that there are still details we don't understand about AGN [active galactic nuclei] like Markarian 501. So, while this effect could be a first sign of quantum gravity (*not* string theory in particular, as others have pointed out), it could also simply be something going on in the intrinsic spectrum of the flares themselves. I'd personally consider the second explanation more likely at this stage.

    As they also point out, one approach to sort out the ambiguity would be to observe other flary AGN at different redshifts (distances). One could then, for example, see if the delay gets shorter or longer as the distance changes, as one would expect with a quantum gravity effect due to propagation to Earth.