Gamma Ray Anomaly Could Test String Theory 128
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.
ahem (Score:3)
Update (August 24th): We're starting to see bloggers weigh in, including the inimitable Lubos Motl and Chris Lee at Ars Technica, though I'm surprised there's not more. Here we finally get some observations that probe string theory, if only tentatively, and people who have been loudly complaining about the lack of such observations have gone silent.
Wow - if that's not a dare to be
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The process of peer review requires that you actually give your peers time to review.
"people who have been loudly complaining about the lack of such observations have gone silent."
If someone's going to get emo over cries of "tests or GTFO," they're in the wrong line of work.
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I don't know, but maybe a blog by a friggin' physicist would do, don't you think? If not, why not?
Life on the lattice [blogspot.com]
number 2 post (at least as I see it) and ... (Score:1)
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Not specific to String Theory (Score:5, Informative)
Re:Not specific to String Theory (Score:5, Insightful)
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.
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The neat thing about String Theory is that it is a coherent mathematical framework and a group of related models that unify the theories of several of the fundamental forces as they are currently understood. Essentially, it can't make pr
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Some physicists have taken certain physical laws as axioms for something like a first-order logic.
The great part about loop quantum gravity is tha
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Well, there's some mass in the medium: the vacuum in the outer space isn't perfect. In fact no perfect vacuum exists.
Relativists could argue this is enough for an effect of 4 min slowdown over 500 million years long travel.
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--
Rent residential solar power: http://mdsolar.blogspot.com/2007/01/slashdot-user
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String theory needs to be falsifiable (Score:3, Insightful)
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Basically you need a situation where the outcomes predicted by string theory, M-theory, relativity, quantum gravity, etc. are different. Then you run an experiment emulating this situation and see which one is right. This doesn't prove a theory but narrows down the possibilities.
If I understand it correctly, right now the problem is that modern theories all expla
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The problem is that string theory predicts absolutely everything! That is, you can make it say anything at all you want by plugging in a few variables. The result will be no more predictive of anything else than before the numbers got plugged in.
String theory is interesting but it is actually too soon to call it a theory. It's more a bag of interesting tools and ideas that may one day be used to build a theory. I wouldn't go so far as to call it a waste of time (though some would), but it's not really wor
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Not only am I angry about Superstrings being hyped and taught as though they were fact, so-called "String Theory" is not even really a theory yet. As Ars pointed out, this is no more evidence for that than it is for other quantum gravity models.
There is an article on the Net (you can find it at YouTube, search for "Ring of Dark Matter" that uses similar propaganda to present a hyp
Re:Not specific to String Theory (Score:4, Interesting)
Yeah, it's even possible to make a pretty reasonable model-independent argument that a variable speed of light must come out of any theory of quantum gravity. Lee Smolin makes a pretty simple model-independent argument that spacetime must be discrete in any theory of quantum gravity. The idea is that the Bekenstein bound [wikipedia.org] says there's a maximum amount of information that can be contained in any region of spacetime (e.g., a black hole has a certain entropy, which is proportional to the surface area of its event horizon). However, if spacetime was continuous, then you could store an infinite amount of energy in any volume of space. (Here [thymos.com] is a longer explanation.) Note that none of this requires any specific model such as string theory or loop quantum gravity. If spacetime is discrete, then there's a scale at which its discreteness occurs, and that corresponds to a certain minimum wavelength that a light wave can have. The propagation of light therefore has to be drastically modified as you approach that scale.
correction (Score:3, Informative)
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Boy, if you're that sensitive the Internet is going to be a very bad experience for you.
reading = !reading (Score:1)
I stopped reading Scientific American for the same reason I don't read USA Today. Because reading it is the same as not reading it.
Now I read American Scientist.
Layman Alert. (Score:2, Interesting)
But who am I to argue with quantum mechanics.
~Sticky
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Arguing with Quantum Mechanics (Score:2)
But that's just me.
Relativity's Dead (Score:5, Informative)
No no no (Score:3, Informative)
The Higgs boson is predicted by the Standard Model, not String theory. String theory will be no more testable with LHC than it ever was. It's not even wrong.
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I am not a physicist, but I am under the impression that finding the Higgs boson would be a major setback for String Theory. So, in this way String Theory is 'testable'.
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This is wrong. Finding a Higgs boson, or several, will not tell us anything about the validity of string theory.
You're confusing two different effects. The masses that appear in the string spectrum -- corresponding to different vibrational states of the string -- are to lowest order integer multiples of the Planck mass. But we will never see anything but the first tier of excitation
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String theory will be no more testable with LHC than it ever was. It's not even wrong.
Actually, parts of string theory (which is really M theory) can be tested by the LHC when it comes online. The part I'm referring to is the existence of extra dimensions. The strings that represent gravitons are the easiest strings to generate and then detect because they require the least amount of energy (because they are closed strings and thus not tied to the brane [part of M theory] of our universe). I forget the exact details (and can't find a reference at this time) but by creating gravitons and de
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If we can create gravitons and send them to another dimension, and detect that, doesn't that mean that if people in the other dimensions can do the same, we can communicate with them?
Graviton telegraph. You heard it here first.
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You thinking of The Gods Themselves by Asimov?
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If we can create gravitons and send them to another dimension, and detect that, doesn't that mean that if people in the other dimensions can do the same, we can communicate with them?
Uh I guess. The "other dimensions" are about 10^(-19)m in size and these are the extra large dimensions. Regular size dimensions predicted to exist by string theory are about 10^(-34)m in size so if you happen to know of anyone capable of living in space of that size then I guess you can start holding your breath for that signal from beyond.
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If we can create gravitons and send them to another dimension, and detect that, doesn't that mean that if people in the other dimensions can do the same, we can communicate with them?
If there exists a fourth spacial dimension, then all of us already do live in that dimension. We just don't perceive it because it's incredibly small , as they theory goes.
Also, just because you can move around a particle along the axis of the fourth dimension doesn't mean that you magically get to ignore the other three. If you want your particle that you manipulate in New York to be observable by your friend in Sydney then the three classical dimensions will need to be traversed before he can see it no m
Correction,experiment will test the standard model (Score:5, Insightful)
If the string theory model fails, it will be replaced with a newer, better version of string theory, with bountiful opportunities for new books, conferences, papers, and maybe even some derivative specialities of study.
YOU CAN'T KILL WHAT LIVES ONLY THE MINDS OF MEN... BUWAHAHAHAHAAAAA!
Re:Correction,experiment will test the standard mo (Score:2)
(Time dilation due to speed? Pft hardly. Maybe there are subatomic particles such as electronics whose movement becomes dampened when approach speed because they have a fixed absolute speed, or even slow downs at the quantum level [maybe], but that doesn't mean tim
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PS I just remembered, your idea of an underlying mechanism was a common idea for a long idea for many scientists including Einstein, it is just that every experiment conceived by them proved them wrong and showed that it was exactly as the theory portrayed. So I wouldn't bet on your idea of how things work to be so certain.
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I think you're talking about special relativity, not general relativity, and that you have never studied it in more depth than at a lay man level. The whole point of special relativity is that time is just an
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If the string theory model fails, it will be replaced with a newer, better version of string theory, with bountiful opportunities for new books, conferences, papers, and maybe even some derivative specialities of study.
String theory doesn't really exist anymore or at least it is old news. String theory turned into superstring theory. Then there came to be multiple string theories that were very similar. About a decade ago Edward Witten created M theory [wikipedia.org] by reconciling the 5 string theory variations that existed. Maybe I'm wrong but my view is that M theory is the leading edge. I just got done reading Brian Greene's The Fabric of the Cosmos so it is pretty fresh in my mind but Wikipedia helped me remember a few things jus
I think you proved the point actually (Score:1)
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M theory is just the latest attempt, but when it loses steam, string theorists will jump on the next "variant" to keep producing the "books, conferences, papers, and maybe even some derivative specialties of study" mentioned by the grandparent, of which Brian Greene's book is an excellent example.
Right, because books, conferences, papers, etc. are only created for theories that can't be proven easily (or ever). String/M theory with regard to being researched and discussed in print is no different than any other theory. Brian Greene's book (Fabric of the Cosmos for those who didn't see my original message) is about more than just string/M theory. In fact, those topics aren't discussed until at least 75% through the book. I assume you haven't read it otherwise you would have known it isn't the sole
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Re:Correction,experiment will test the standard mo (Score:2)
Re:Correction,experiment will test the standard mo (Score:2)
How do you kill what which has no life?
If you kill a sand worm, it will only shatter into many sand trout to form other worms.
Pah! (Score:3, Funny)
More "String-Theory" Propaganda (Score:1)
Perhaps this will help sort things out, and even boost one or more of these ideas into actual theory status. Until then, it is premature to imply that this research constitutes e
Important caveat (Score:5, Insightful)
"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.
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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.
Yeah, could you say more about this? My basic picture of an AGN would be that you hav
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[TMB]
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Most AGN are variable, most likely due to hydrodynamic instabilities in the accretion disk around the black hole
So why isn't it possible to have one flare that emits relatively low energies, and then four minutes later a second flare that emits relatively high energies?
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Occam's Razor (Score:3, Interesting)
The gamma rays are due to infalling material. Flares are due to sudden large amounts of material falling in. As it falls in it gets hotter. The frequency of the emissions increases as the material heats, going from lower gamma rays to higher gamma rays. These are all accepted as fact. The hypothetical: The 4 minute delay is the time it took for the material to fall in far enough to raise the emission frequency by the observed amount.
Much simpler and neater. Even if I had the observed data and the data on the mass of the galaxy observed, I'm not capable of the relevant calculations, but the logic follows.
On the other hand, Willam of Ockam didn't have a razor -- he had a beard. Einstein trumped Newton with a more complex theory, so the parsimony beloved by scientists doesn't always hold. But in this case, I suspect it will.
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The CEO reminded me that Newton only described, and admitted he didn't know how it worked, but Einstein explained which led to testable hypotheses. Thus the former was not much of a theory if at all by the definition, whereas the latter is a very good example of a theory.
I had no idea she paid that much attention to my caffinated breakfast table rants. Obviously I don't.
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On the other hand, Willam of Ockam didn't have a razor -- he had a beard. Einstein trumped Newton with a more complex theory, so the parsimony beloved by scientists doesn't always hold. But in this case, I suspect it will.
Although it is true that sometimes the simplest explanation isn't the right one, the breakdown of Newtonian physics at relativistic speeds isn't an example of a failure of Occam's Razor. We say that the simplest explanation that fits observations tends to be the right one. Since Newton's equations don't work at relativistic speeds, it doesn't fit observations, so it's obviously incomplete. That's why it gets trumped. If relativity made the exact same predictions, then we'd say that this whole relative
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So Darwin was right, but his whole theory is breaking down with time. Survival of the fittest my ass. Survival of the economic producers and consumers, nuts to everyone else. Only stupid people are breeding. I'd really like to think tha
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Is it "parsimonious" to say Einstein generalised Newton? - One of Newton's stated assumptions was "time is constant".
OTOH: 100 or so years after the Principa was published a (French?) woman of noble birth corrected Newton's kinetic energy equation by emprical means (ie: dropped steel balls into clay and mesured the craters).
Re:Occam's Razor (Score:5, Interesting)
> birth corrected Newton's kinetic energy equation by emprical means (ie: dropped
> steel balls into clay and mesured the craters).
You're thinking of Emilie du Chatelet, paramour of Voltaire. I don't know how noble, but her family lived in a 30 room apartment overlooking Tuileries gardens in Paris. Certainly rich by birth, and married to a rich French military officer who conveniently left on a polar expedition.
And you're not quite correct about what she did; it was much better than that. The dropped ball and clay experiment was done by Willem 'sGravesande in the Netherlands, but he didn't have the theoretical background to understand what he had -- the craters got deeper with the square of the height (== energy). Liebniz had previously specified that energy should increase with the square of velocity, but that was somewhere between intuition, anti-Newtonian leanings (Newton got credit for calculus rather than he; Newton was pushing for mass times velocity, no square) and fortuitous guesswork. He didn't have the practical sense to develop a means to test it (or perhaps thought that beneath him). What du Chatelet did was put the two together and show the precise relationship between energy, mass and velocity that was supported by the data: E = mv^2.
Smiling Uncle Albert had it half written for him. What he plugged in was c for the Latin celeritas (rapidity), which he showed to have a limit of the speed of light, and that the E and m then equated completely and were thus interchangeable through it. Had she had the verification of Roemer's measurement of the speed of light to work with (said verification was just a few years old and not widely accepted yet) and had more time to work on it (she died from an infection after giving birth) she might have made progress towards that herself.
If she had done so, Poincare probably would have grasped the significance of his "theory of relativity" (Uncle A. never used that term until well after it became popularized, but Poincare used it explicitly in his own) and formulated the famous equation himself. He was, after all, right on the verge of it, and refused to talk about Ol' Al forever more because he failed to get all the way there first. It riled him no end, until the end of his days. Had he been younger and the age earlier, he might have challenged the young Bavarian Jew to a duel. A duel such as Francois-Marie Arouet threatened against a certain French nobleman, which resulted in his expulsion from France to England, where he learned of Newton and his work, which he brought back to France, along with his nom de plume, Voltaire. Or the duel (fencing match, actually) in which Jacques de Brun, the head of the King's bodyguards, was bested by a 16 year old girl named Emilie de Breteuil, as such was her family's name when they lived above Paris's Tuileries gardens.
If this was Connections, and I were James Burke, I'd be making a lot more money than what I'm getting for having written this. I am, however, every bit as pretty as Burke on camera, which is to say not at all.
Bravo! (Score:2)
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Thankyou, I always forget her name as well as other details. That peice really is worthy of Burke, the thought even occured to me before I read the last line. I was addicted his column in Scientific american decades ago, I particularly liked the one explaining why the diameter of the space shuttle
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> of Burke, the thought even occured to me before I read the last line.
My wife made the same observation as I was preparing to submit it. The last line was hidden in the editing window. The construction was my own, but my source of information and inspiration was David Bodanis's "E=mc^2: A Biography of the World's Most Famous Equation". A very good science and technology history book in the spirit of Burke's work
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The explanation for everything must be God then. That's as simple as it gets. I'm not sure how the mass interpretation of Occam's razor became going with the simple explanation. What does that have to do with a razor anyway? It seems to me the correct interpretation is Cut the crap.
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String "theory" (Score:2, Interesting)
Re:String "theory" (Score:4, Informative)
Actually, there are a great many phenomena that string theory explains, the subject of this story, for example is potentially one of them, there's also some things about black holes (like Hawking radiation) which string theory predicts, but other theories also predict Hawking radiation.... plus there's a whole host of things that it predicts that occur at very high energies. But that's essentially the problem with string theory. The kind of things string theory predicts that would confirm it require energies that we are simply incapable of achieving, and the more mundane predictions made by string theory also happen to match predictions by competing non-string theories, making it pretty much impossible for string theory to distinguish itself using modern technologies.
That being said, I think string theory is beautiful, however, it could very well turn out to be the most beautiful theory of physics ever constructed as well as the biggest dead end.
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Well, let's just take something really simple. String theory predicts the existence of...wait for it...strings (or branes depending on which form you are talking about) and extra dimensions. If the geometric structure of one of these things could be detected, that would be THE thing that would confirm the hypothesis beyond any shadow of a doubt. Directly detecting a string though runs into what I alluded to in my previous comment. The energies required to do this are beyond anything we are currently capabl
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Well, the fact that other theories also predict the same effect means that a confirmation of the effect validates all the theories that predict the phenomenon, without really distinguishing one from the other. Although if the magnitude of the prediction varies between different theories then it is possible to distinguish one from the other. For example, this was how general relativity was confirmed for the first time during an eclipse. Both relativity and Newtonian gravity predicted that the sun would de
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Have you taken a look at String theory [wikipedia.org] yet?
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xkcd to the rescue (Score:1)
The Full Paper (Score:2)
http://xxx.soton.ac.uk/abs/hep-th/0501117 [soton.ac.uk]
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http://arxiv.org/abs/0708.2889 [arxiv.org]
Variable lightspeed does not violate relativity (Score:2)
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A variable speed of photons means a variable speed of light. And that does violate relativity theory since one of the postulates on which the theory is based is a constant speed of light in all reference frames.
If you look into the history of light-speed measurements, you'll see that there is actually quite a bit of other evidence for a variable speed of light. The measured variations are small but well within detection capability of the ex
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Are you talking about the errors of the experiment? Well, no device is perfect, all of them create errors.
If you read the article, you'll see that the precision of similar experiments have grown a lot, and such errors never repeat on a highter precision experiment.
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No, I am talking about deviations from c markedly larger than the expected error magnitude of the instrument in question. Another series of experiments you might want to look at are those of Dayton-Miller. In particular his original papers and what the man himself thought http://en.wikipedia.org/wiki/Dayton_Miller [wikipedia.org]. There have been concerted attempts to explaining away those results by defenders of relativity theory...
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Well, I can not explaint things better than the link you posted (maybe you should read it again). But I can point you that newer and more precise experiments weren't able to reproduce the results (your link points to some of them).
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If you read carefully, you can see what his experiment found, and that the validity of those findings has retained support. That others tried to explain the results away is not surprising: obviously relativity has won the war of words and minds. The neutrality of the article is under dispute for a reason. One side would like you to please move along, nothing to see here, which you of course would prefer to do r
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There is no even remotely conventional way to explain such a result.
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Hold yer horses!
In classical physics, the speed of light is a derived quantity: c = 1 / sqrt(epsilon * mu). Epsilon is the electrical permittivity of the vacuum, the degree to which an electric charge induces dipoles in (polarizes) the vacuum. Mu is the magnetic permeability, which arises from the geometrical effects of the Lorentz transform for particles in relative motion.**
As a geom
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First, photons have no mass. If you find some new particle with mass, well, it is not a photon. That is by definition.
Second, relativity says that particles without mass travel exactly at C. That includes photons.
Third, modern relativity comes directly from eletromagnetism. Both theories use the same experiments to calculate the light speed (actualy, C is defined, so those experiments ended up as the definition of a meter), so both have the same precision.
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Your understanding of the relations between the theories and experiments needs some work. You can make a theory that has photons with mass 0 by definition, but photons are also experimental things. If a photon turns out to have mass it ruins the theory, but you're not suddenly going to call it by another name. Physics is not axiomatic mathematics.
Nobody expects photons to have a mass. If photons had a mass it would be a disaster for some theories but not for
clarification (Score:1)
First of all, this observation is FAR more likely to be due to variations at the source (which may have simply emitted the high-energy photons a little later than the low energy ones) then to some huge new discovery.
Second, if this really is due to fundamental physics, it's a violation of Lorentz invariance (special relativity) and it would be about the best possible *disconfirmation* of string theory you could ask for (IAAST). If there's one basic prediction of
ST has been tested as much as the SM (Score:1)
So, star maps may also be flawed (Score:1)
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C has changed, along with other "constants".
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What is the drift of C over 4B years? How could we even calculate an unknown drift value?
A potential problem for GEM (Score:1)
Like a good
http://www.bautforum.com/against-mainstream/61876- gem-rank-1-unified-field-proposal.html [bautforum.com]
One test is to measure bending of light to second order PPN accuracy, basically a million times more than was needed to tell the difference between GR and Newton. Do that for GR
Simple... (Score:2)