Hints of a breakdown of relativity theory?

[metadigital]

The MAGIC gamma-ray telescope team has just released an eye-popping preprint (following up earlier work) describing a search for an observational hint of quantum gravity. What they've seen is that higher-energy gamma rays from an extragalactic flare arrive later than lower-energy ones. Is this because they travel through space a little bit slower, contrary to one of the postulates underlying Einstein's special theory of relativity -- namely, that radiation travels through the vacuum at the same speed no matter what?

The team studied two gamma-ray flares in mid-2005 from the black hole at the heart of the galaxy Markarian 501. They compared gammas in two energy ranges, from 1.2 to 10 tera-electron-volts (TeV) and from 0.25 to 0.6 TeV. The first group arrived on Earth four minutes later than the second. One team member, physicist John Ellis of CERN, says: "The significance of the time lag is above 95%, and the magnitude of the effect is beyond the sensitivity of previous experiments."

 

Either the high-energy gammas were released later (because of how they were generated) or they propagated more slowly. The team ruled out the most obvious conventional effect, but will have to do more to prove that new physics is at work -- this is one of those "extraordinary claims require extraordinary evidence" situations. But if the high-energy gammas really did lose the cosmic race, we're talking Big Discovery. It could be a way to constrain string theory, loop quantum gravity, and other bleeding-edge theories.

 

The basic picture is that high energies might cause small-scale fluctuations in the shape of spacetime, which would act as subatomic lenses. The higher the photon energy, the more it might induce such lensing and the slower it would cover large distances. Four minutes isn't much of a delay over a half-billion-year journey, but then again, you don't expect much. From the lag, you can deduce where quantum gravity kicks in. Some theories predict the effect is proportional to the quantum-gravity scale, in which case it happens at 5 x 10^17 giga-electron-volts (GeV). In others, it's proportional to the square of the scale, in which case the lag implies 6 x 10^10 GeV.

 

I need to look into this a bit more, but I just wanted to get the news out there for people to mull.

 

Update (August 23rd): Another co-author, string theorist Dimitri Nanopoulos of Texas A&M, writes to me: "I am very excited about this, because as you know we suggested this effect about ten years ago and we have follow through with several analyses and/or improvement on theory. Notice that the 0.4 x 1018 GeV is the typical string scale!!!!"

 

Daniel Ferenc of U.C. Davis on the MAGIC team writes: "There have been attempts to observe time lags in gamma flares and in gamma-ray bursts, but we have never seen something like this.... We should keep in mind that the effect may still be inherent to the process of the emission of gamma rays in the source, although not very likely. We are rapidly learning about such emission processes in AGNs from new data collected by MAGIC, HESS, VERITAS, and CANGAROO, in coincidence with x-ray and optical measurements, and will know more soon."

...

 

clickie

[Tale]

Very interesting. I'd stroke my goatee, but I've been shaving.

Edited August 31, 2007 by Tale

[metadigital]

I have a goatee at the moment. It is a good stroking target. I may eventually get a pipe, too.

[Guard Dog]

There seems to be a few too many unknowns to be so excited at this point. For them to judge the speed of the first flare to be faster the second assumes:

 

1) That there were emitted simultaneously

2) That they were emitted from the exact same point.

 

I'm not an astronomer but it seems to me that it is impossible to eliminate doubt on those two points. Even the article's update confirmed they can not rule out an event at the source of emission to explain the difference. But if it turns out to be true I guess we will all have to go back to school.

[metadigital]

You're right that it's too early to be making definitive statements about the end of quantum relativity ... though the caveats you (rightly) mention are less probable than the dramatic conclusion, I feel.

[Gorgon]

Let me be the first to admit that this is out of my league as far as knowledge of special relativity and quantum physics.

[Guard Dog]

It would not be the first time in history that a team of educated people witness an event that current physics cannot readily explain, and they assume that physiscs is wrong rather than some flaw in the observation.

[Rosbjerg]

Human pride is a funny thing. 1, they don't want to be wrong - 2, it would rock for any scientist to rewrite the theory of relativity. So I think it's natural they jump to the most "convinient" conlusion.

[Guard Dog]

If their claim is true then radio mechanics as I understand it would not work. Case in point. Suppose I were to place two narrow band microwave radios on a hill and shoot them to two radios on a distant hill. Assume both are on the same frequency, and modulation, and their paths are parallel, and both are transmitting from a single source. If I set one to 30 dBm (one Watt) and the other to 33 dBm (two Watts) I know they will be in phase with each other at the z end of the shot (signals will arrive at the same time irrespective of power).

 

That is why I strongly suspect there is a observational flaw here rather than a new discovery.

[taks]

i think they're getting at a difference in energy, not power. two equal frequency waves have the same energy per particle (it is a function of wavelength, energy is inversely proportional to lambda), and the difference in power in your example GD is, essentially, increased particle density, but each particle would have the same frequency/wavelength. either way, from what these guys are saying, the difference over non-relativistic distances, such as terrestrial experiments as your example, would be undetectable by standard means...

 

i'm not sure what to take of this. does this mean the red-shift as originally proposed by hubble is correct (hubble actually believed in a sort of "tired light" theory, not the standard galaxies in recession theory)? it'll be interesting to see how this works out, if at all. i am skeptical as well.

 

taks

[Lyric Suite]

Creationists are going to be all over this.

[taks]

no they won't. such a discovery lends no credence to their beliefs, though it does potentially offer alternatives to the expanding universe theory.

 

taks

[Lyric Suite]

no they won't. such a discovery lends no credence to their beliefs, though it does potentially offer alternatives to the expanding universe theory.

 

taks

 

I was referring to the whole OMG PHYSICS R WRNG SCIENCE IS A LIE EINSTEIN WAS A DIRTY ZIONIST!!!1 ordeal.

Edited October 2, 2007 by Lyric Suite

[taks]

sure, they could try to use that, but it still doesn't help the case of creationism itself. if anything, it bolsters the idea that the universe is 13 billion years old, but behaving in a slightly different manner than mainstream thought otherwise believes.

 

taks

[metadigital]

what these guys are saying, the difference over non-relativistic distances, such as terrestrial experiments as your example, would be undetectable by standard means...

Just a quick "hear hear" to this thought ... the laws of physics only start to show their limitations at their limits ... hence super-massive stars, etc.

i'm not sure what to take of this. does this mean the red-shift as originally proposed by hubble is correct (hubble actually believed in a sort of "tired light" theory, not the standard galaxies in recession theory)? it'll be interesting to see how this works out, if at all. i am skeptical as well.

Not sure either, though I am pleased to have some more data (even and especially if it doesn't agree with existing theories). The recession speed of galaxies sufficiently distant from us start to stretch the whole "expanding space" model to its breaking point, methinks. The most distant object seen (a QUASAR) must be travelling away from us at better than a third the speed of light ... again this is the fabric of spacetime stretching, so there would be no physical clues, but it does pose some significant questions. Like will the expansion speed of the universe keep accelerating (if that is indeed what the red-shift of the emitted light does actually indicate)?

[Colrom]

Is it possible that the path lengths (geodesic distances) are different because of the mass differences?

 

Just a thought.

Edited October 3, 2007 by Colrom

[Guard Dog]

You are right Taks, that was not such a great example. I did not do that well in physics I'm afraid. I got a C in both classes. But I got an A in both Statics and Dynamics which are really just applied physics. Go figure.

 

These days I'm seeing microwave paths even in my sleep.

[taks]

Is it possible that the path lengths (geodesic distances) are different because of the mass differences?

yes and no. that's sort of what they were hinting at with the "lensing" effect that impacts the differing particle energies in a slightly different manner. not really path length difference, but more of a "harder road to travel" due to space-time differences at different energies, kind of idea. at least, that was my take on it.

 

taks

[DeathScepter]

*strokes his evil goatee*

 

 

 

Interesting. Me likely.