Gamma-ray photon race ends in dead heat; Einstein wins this round
October 28, 2009
In this illustration, one photon (purple) carries a million times the energy of another (yellow). Some theorists predict travel delays for higher-energy photons, which interact more strongly with the proposed frothy nature of space-time. Yet Fermi data on two photons from a gamma-ray burst fail to show this effect, eliminating some approaches to a new theory of gravity. Credit: NASA/Sonoma State University/Aurore Simonnet
Racing across the universe for the last 7.3 billion years, two gamma-ray photons arrived at NASA's orbiting Fermi Gamma-ray Space Telescope within nine-tenths of a second of one another. The dead-heat finish may stoke the fires of debate among physicists over Einstein's special theory of relativity because one of the photons possessed a million times more energy than the other.
For Einstein's theory, that's no problem. In his vision of the structure of space and time, unified as space-time, all forms of electromagnetic radiation - gamma rays, radio waves, infrared, visible light and X-rays - are reckoned to travel through the vacuum of space at the same speed, no matter how energetic. But in some of the new theories of gravity, space-time is considered to have a "shifting, frothy structure" when viewed at a scale trillions of times smaller than an electron. Some of those models predict that such a foamy texture ought to slow down the higher-energy gamma-ray photon relative to the lower energy one. Clearly, it did not.
Even in the world of high-energy particle physics, where a minute deviation can sometimes make a massive difference, nine-tenths of a second spread over more than 7 billion years is so small that the difference is likely due to the detailed processes of the gamma-ray burst rather than confirming any modification of Einstein's ideas.
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Credit: NASA/Sonoma State University/Aurore Simonnet
"This measurement eliminates any approach to a new theory of gravity that predicts a strong energy-dependent change in the speed of light," said Peter Michelson, professor of physics at Stanford University and principal investigator for Fermi's Large Area Telescope (LAT), which detected the gamma-ray photons on May 10. "To one part in 100 million billion, these two photons traveled at the same speed. Einstein still rules."Michelson is one of the authors of a paper that details the research, published online Oct. 28 by Nature.
Physicists have yearned for years to develop a unifying theory of how the universe works. But no one has been able to come up with one that brings all four of the fundamental forces in the universe into one tent. The Standard Model of particle physics, which was well developed by the end of the 1970s, is considered to have succeeded in unifying three of the four: electromagnetism; the "strong force" (which holds nuclei together inside atoms); and the "weak force" (which is responsible for radioactive decay, among other things.) But in the Standard Model, gravity has always been the odd man out, never quite fitting in. Though a host of theories have been advanced, none has been shown successful.
But by the same token, Einstein's theories of relativity also fail to unify the four forces.
"Physicists would like to replace Einstein's vision of gravity - as expressed in his relativity theories - with something that handles all fundamental forces," Michelson said. "There are many ideas, but few ways to test them."
The two photons provided rare experimental evidence about the structure of space-time. Whether the evidence will prove sufficient to settle any debates remains to be seen.
The photons were launched on their pan-galactic marathon during a short gamma-ray burst, an outpouring of radiation likely generated by the collision of two neutron stars, the densest known objects in the universe.
A neutron star is created when a massive star collapses in on itself in an explosion called a supernova. The neutron star forms in the core as matter is compressed to the point where it is typically about 10 miles in diameter, yet contains more mass than our sun. When two such dense objects collide, the energy released in a gamma-ray burst can be millions of times brighter than the entire Milky Way, albeit only briefly. The burst (designated GRB 090510) that sent the two photons on their way lasted 2.1 seconds.
2 hours ago
Plasma pinches have that profile. This is only slightly different than the merging of two bodies theory.
None.
Exactly the same as The String Hypothesis which actually does have numbers. Only unlike Alexa-Alizee it too many rather than none at all.
Alizee:
Neutrinos trailed the visible light of 1987A by many hours. So if they preceded gamma rays, in any particular instance, it is likely due to the source being both much closer than the Magellanic Clouds and generated before the gamma rays.
Ethelred
Of course there is no String Theory since, technically anyway, it doesn't yet tell us anything about the universe that can separate it from the Standard Model. So there is no way to take it out of the hypotheses stage.
Maybe someday.
The point I was making is that Aetherwave Theory ISN'T theory anymore than String Theory is theory. One is a hypothesis. The other is a vague, variable, highly amorphous concept in search of a hypothesis.
Both tell us nothing about the Universe. At least nothing that anyone can test.
GR has been tested and so far fits the evidence. This gamma ray data fits GR exceeding well so there is no need to suppose exotic vortexes. Now if you can find an reason for a vortex occurring and calculate a dispersal curve that could be a point in your favor with enough data.
Ethelred
http://arxiv.org/.../0209264
Loop Quantum Gravity doesn't predict Lorentz symmetry violation in this case.
http://arxiv.org/.../0702016
Because prof. Smolin is an author of both theories, many people are connecting LQG with Lorentz speed violation, but it's incorrect interpretation. I'm explaining it on my blog.
It has nothing in it to cause the speed of light to be affected by its energy level. If light WAS effected by its energy level then GR would be violated.
False
False
Microwave photons are inherently lower energy than Gamma rays. The energy of any photon is directly related to its frequency/wavelength.
Temporary yes. But that is the end of the gamma ray, permanently. So it won't cause a dispersion of the time of arrival since it won't arrive. It may affect the energy distribution.
False
True
Ethelred
I WAS talking about GR not SR so that is irrelevant. So is the microwave background.
Same thing in a vacuum. You do know that SR is a subset of GR don't you? You sure aren't acting like it.
Light waves don't interact with each other that way. Something to do with Spin.
And hand waving is another. At least you seem to fond of it anyway.
True. It was arrival times. Which are certainly effect by departure times if the velocity is the same.
Its possible that wishing works. Neither has evidence.
Ethelred
If particle-antiparticle pair forms only 0.0000001% of total gamma photon life, it still means, such photon cannot propagate by speed of light completely, because material particles always propagate in subluminal speed - just because of Special Relativity. Anyway, it's not my intention to force you my truth - the future experiments will show us, who was right in this case.
The trick is, many gamma ray flashes disperse fast - only those, which contain correct mixture of photons of proper wavelengths can travel across whole universe - so they can be observed at Earth at distance. It's an example of evolution of energy.It has an evidence. Shorth distance gamma ray flashes are quite dispersive with compare to very distant ones and neutrinos often advance them.
Its not a percentage situation. Its an end of existence.
If a gamma ray produces a particle/anti-particle pair it is no longer a gamma ray and therefor will not arrive here. Thus it does not contribute to the measurement of gamma rays here.
To put it another way the gamma ray has to arrive for it to be detected. It can't arrive if it becomes a pair of particles before detection. Therefor pair production will not effect the arrival time since it won't arrive.
Ethelred
Neutrinos have mass. Gamma rays don't. Therefor the only way for a neutrino to arrive before gamma rays is for them to generated first or for the gamma rays that were created at the same time to be blocked. Which fits the known causes of gamma rays and neutrinos.
Both can be created in violent events deep inside massive objects or on the surface of white dwarfs. However gamma rays cannot escape from the interiors of massive objects or even a dense accumulation of hydrogen on a white dwarf, in a straight line. Neutrinos can.
Since the events you mention are near, the difference in escape time is not overwhelmed by the higher velocity of the gamma rays after they finally escape.
Ethelred
I know, many textbooks are memorizing like parrots, photons have no mass, only momentum. But you cannot believe in every nonsense from textbooks blindly - or you become religious parrot as well.
It isn't lost. Its dispersed as energy and gas. A tiny amount is converted to neutrinos.
A photons mass is its energy. As in E=MC2.
If you want to claim that photons have mass that is unrelated to its frequency then you have a to prove it. After all this time someone should have noticed. YOU should found something lurking in someones work by now. So I will go on the standard idea that a photon's mass is due to its energy.
Religion is right out. I will stick with being an Agnostic as that is all the evidence supports.
Ethelred
But if you want to believe in general relativity, no one prohibits you in it. The phenomena described is just a result of general relativity - but it's not a product of flat space-time, but a product of many subtle space-time deforms, resulting from cosmic microwave background fluctuations.
Which goes in a random direction. Therefor not in a straight line so we don't detect it.
Ethelred
Thanks but I already said that. I just used a different formula.
Too much hand waving anyway. Just how short are your arms that you think can't see them waving?
Do you practice hand waving at beauty pageants?
Presume all you want. I prefer evidence.
The evidence doesn't prohibit even you from GR. Just your religion.
Two can play that game and since I use evidence and you wave your hands and call it a theory, you are the one with a religion.
Ethelred
But the pair formed by materialization of very heavy photon and very lightweight one has a nonzero momentum toward direction of original - so after annihilation it continues in original line of travel and lightweight photon is restored. Macroscopically the gamma ray photon remains only slightly deflected from its path by spacetime deform of lightweight photon like by tiny gravitational lens.
In negation of your hand waving and in agreement with actual evidence. So its not religion on my part. Your wild speculation doesn't qualify as explanations.
I am waiting for yours. Mine is all over the Universe. Heck the GPS system wouldn't work if GR was significantly wrong.
I know that English isn't your first language but you really need to look at the definitions of Religion and Agnostics before you make things up next time. It would really help if you used actual English words instead of learning them from Creationists.
Agnostic is the optimum for all non-religions thinking. It avoids the dogmatism of Atheism. I go on evidence and reason. Not hand waving and wishful thinking.
Ethelred
The article is about dispersion IN TIME. Not space.
Would you care to actually give a link that supports that statement? Not a link to your site by the way but someone independent. Without hand waving and with evidence.
Ethelred
http://tinyurl.com/yzkldl6
But it's quite logical. What would you expect, when heavy and light photon annihilate and restore back? Would you expect symmetric dispersion of energy? This would violate momentum conservation law. Jeez, photons are moving by (nearly) speed of light. Every dispersion in space results into dispersion in time, too.
You do know that GR deals with CURVED SPACE don't you? I did mention that the involvement of a gravitational lens could produce a lot more information.
So don't put words in my mouth. Or rather on the net and claim I said them.
So far all the evidence is that space is quite flat. The background fluctuations are about two parts in 10,000.
Ethelred
Sorry but I am not paying to read that. The abstract doesn't support you in any case.
Was that a bluff? Or did you just not read the abstract.Its about spin in any case.
Ethelred
Would you care to actually give a link that supports that statement? Not a link to your site by the way but someone independent. Without hand waving and with evidence.
How many times are you going to see the same thing and ignore it? Dispersal in SPACE results in NON DETECTION.
If it is dispersed in space it will not be detected on the same line as photons that are not dispersed.
We are talking about something that is billions of light years away. An exceedingly tiny deflection angle will result in missing the whole bloody galaxy much less our detectors.
Ethelred
By using actual evidence. As in COBE.
http://map.gsfc.n...uct.html
And copying my style won't help you if you don't have evidence.
Its the way I do it on most sites. I am not only person here that uses a signature. Most sites do it automatically.
There a several reasons that I use a signature. Its traditional in most forums. On some forums some wanker has already used Ethelred but doesn't post. For instance the physics forum that Physorg is linking too has such a non poster. Two posts and the second was his own reply to his first. On sites like that I use Ethlred with the middle E left out and then use the right spelling in my sig.
Thorough yes. Rigid, well the girls like it that way.
Use evidence and you won't have to descend to ad homonyms.
Ethelred
Thus resulting in deflection again and again. Thus resulting in non-detection. Even assuming it happens as you describe, which is doubtful.
This strikes me as a blatant case of Spherical Chicken thinking.
If it is traveling along a 7 billion light year long line between the source and the Earth it has seven billions light years of VOLUME to deflect into. That is quite a large sphere and the Earth is an exceeding tiny portion of it. The only light that is going to reach is light that was emitted in the direction of that line and is UNDEFLECTED along the way. Pair production will result in deflection.
Claiming that the mutual gravitational attraction between photon is significant is quite an imagination.
Ethelred
Of course not. Didn't claim it did. Nor is that what you asked for.
Interesting how you lose track of the discussion.
It has to do with your claim of non flat space. Evidence as opposed to bare faced claims unsupported anything except the waving of your hands. Apparently you think the wave length of your hands has something to do with the curvature of space.
Ethelred
You're talking about energy anisotropy of CMB, which is in 0.0002 Kelvin range. I'm talking about anisotropy (space-time curvature) of single CMB photon. For illustration: I can put many stones from altitude 10,0 +- 0.0002 meters to your head. These stones can still kill you safely - although their anisotropy in potential energy distribution remains quite low.
But now, a question please:
My understanding of partcile physics says that gamma rays, like any other photons of whatever energy, do not have mass or charge; hence, they cannot react with any other entity and can at most only be absorbed. Therefore, why did anyone expect to see any sort of glancing interaction with the "quantum foam", even if that foam created charged or uncharged virtual particles?
It seems - despite I'm aetherist - I'm still the only person, which/who believes in these equations here.
Perhaps if you weren't a HandWavist you would have noticed that I have pointed out the photons have energy and therefor mass.
Twice already.
This is the third time.
Learn to read.
Which is not the same as claiming you can't read.
You can.
You just don't.
Ethelred
Lets see, non detection results in all that PLUS detection.
Amazing.
Thats multiple times you have made ludicrous conclusions based on NON_DETECTION.
Even by Physorg standards that is a high level of anti-achievement.
I am talking about your claims of fluctuations in the curvature of space. Which would show up in the CMB. And don't.
Your inventing things that don't exist. Unless of course you have EVIDENCE. Something you have yet to show.
Really. Amazing. Safely killed.
And without any relevance at all as well.
Perhaps if you wave your hands faster and harder you can fly.
Your HandWave WAG has even less chance of flying.
Ethelred
Whole story started before two years already, when MKN501 event was observed. This gamma ray burst occurred at much closer proximity, then the GRB090510 - and MKN501's high energy photons were delayed by more then thirty seconds.
This sounds a bit strange, doesn't it? This is quite common approach in physics. Negative result is result, too. Just try to remember the extrapolations of negative result of Michelson-Morley experiment.
As far as I know, there is no confirmation of what exactly produces GRBs. So, this line should include at least one "probably" or "most likely" if it intends to be scientifically correct.
But we still don't know, if this cluster moved in speed of light, the speed of microwaves in particular. For example, whole Earth planet is composed of bosons of different wavelengths, but it still propagates through vacuum as a single body by subluminal speed. So it violates Lorentz symmetry heavilly, although every boson in it travels along complex spiral path, along which Lorentz symmetry is maintained. The funniest part is, both interpretations are correct at the single moment.
What we are facing is sort of natural selection process - just applied to cluster of gamma photons.
This model has even its own analogy from common life. During heavy rain dense water droplets are forming kind of metamaterial foam in atmosphere. When we are observing rainbow, we can often see the dark area between primary and secondary rainbows. It corresponds the angle of observation, in which the dispersion of light by inner and outer surfaces of water droplets becomes balanced. In such direction particle environment slows down the energy spreading - but it still doesn't exhibit the dispersion.
In my opinion, this is exactly the case of vacuum, which we are observing at cosmic distances via gamma ray bursts. This geometrical model of vacuum goes pretty deep, as it explains, why universe exhibits universal symmetry violation, omni-directional space-time expansion, event horizons and other theoretical stuffs. But it explains too, how is it possible, we cannot observe dispersion of gamma ray photons JUST at large distances.
Thank you for your attention and sorry for flooding.
Photons have zero rest mass but non-zero relativistic mass, usually what is meant by mass is rest mass.
Photons can react with charged particles without being absorbed, google Compton scattering for example.
As for the interaction with the "quantum foam" the prediction was based on the postulated shape of spacetime on extremely small scales, photons are affected by spacetime, for example massive bodies such as stars induce enough curvature in spacetime to lead to observable bending of photons paths. I don't know however how exactly pair creation comes into this picture.
Sorry if I missed it in an earlier post, way too much stuff to go through before work.
Thanks.
Because photons are of different energy, resulting cluster wouldn't be homogeneous, the more heavier photons would go to the center of cluster, thus mimicking tiny gallaxy or planetary system. Maybe the lone high energy photon was trapped into photon cluster from outside, maybe it even served as a nuclei of cluster simmilar to condensation of water droplets from atmosphere.
In general, cluster formation doesn't mean, Lorentz invariance is maintained, because the whole cluster could move in slightly subluminal speed.
The reason, why Nature didn't considered this possibility is probably in widespread belief, photons have no mass, only momentum.
http://www.physli...e270.cfm
The acceleration of gravity on an object only appears to be independent of the mass of the object. After all, inertia - resistence to a change in motion - is much greater for a more massive object. This has implications for the photon background acting on the photonic wavelength. After all, energy "is" mass.
Observation of gamma rays is significant in its combination of extremelly high energy density, which propagates at extremelly high distance (combination of extreme high and low space-time curvatures). Nowhere in terresterial lab such combination can be achieved. This makes research of gamma rays so usefull in understanding of fundamental principles, which are driving observable Universe.
at different times at the source ? It may be
clear to all the professionals here, but the
article seemed sparse on this.
So yes they could easily have been generated at different times. Nine tenths of second is close enough together to have been created in such a merger. There is no need to suppose that they had to have been created simultaneously. The article was clear enough on that point.
Link to an article about the same paper.
http://arstechnic...urst.ars
It seems pretty clear that the event was of a very short duration but long enough for a one second window for the generation of high energy photons.
In other words they could indeed have been generated at different times as long as you consider an interval of about one second to be at different times. Seems that most do.
Ethelred
http://www.aether...ring.gif
Here we can met another low-energy analogy of closed D-strings, which are attached to space-time brane in so-called the Falaco solitons, which are spreading along density gradient, which is forming water surface.
http://www.youtub...wZ39EDmw