A hint that quantum fluctuations in the fabric of the universe slow the speed of light has not been borne out in observations by NASA's Fermi telescope. The measurements contradict a 2005 result that supported the idea that space and time are not smooth.
Einstein's theory of special relativity says that all electromagnetic radiation travels through a vacuum at the speed of light. This speed is predicted to be constant, regardless of the energy of the radiation.
Yet in 2005, the MAGIC gamma-ray telescope on La Palma in the Canary Islands suggested the speed of light might not be constant after all. The telescope, which measured the light released by a galaxy around 500 million light years away, found that higher energy photons arrived four minutes behind
their lower energy counterparts.
Grainy universe
The discovery hinted that the speed of light may change depending on its energy. This effect could be a consequence of some theories of quantum gravity, which attempt to unify Einstein's theory of gravity with the laws of quantum mechanics. These models postulate that space and time are not smooth. Instead space-time is inherently grainy, fluctuating rapidly over distances of about 10-35 metres, a length called the Planck scale.
If space-time is grainy, higher-energy photons would move more slowly than their lower-energy counterparts. That's because higher-energy photons have smaller wavelengths, which makes them more sensitive to tiny fluctuations in space-time.
However, the MAGIC lag was apparently too large to be easily explained by graininess on the quantum scale. If the delay were caused by fluctuations in space-time, they would have to occur on scales more than 10 times larger than the Planck scale.
"This intriguing evidence has been wandering around in the quantum gravity community for more than a year now, with hope on the progressive side, and stomach aches on the conservative side," says physicist Giovanni Amelino-Camelia of Sapienza University of Rome in Italy.
Now new observations suggest quantum gravity cannot be responsible for the time delay observed by MAGIC. The light from a powerful, 7-billion year old gamma-ray burst detected by NASA's Fermi Gamma-ray Space Telescope shows no evidence of a lag between photons of a range of energies.
"We have fewer stomach aches now," says Amelino-Camelia. "The Fermi data has pushed the limit where it's now proven the MAGIC data cannot be interpreted in that way."
Light artefact
Fermi's measurement is the most stringent direct limit on how much the speed of light might vary with energy, says Jonathan Granot of the University of Hertfordshire in the UK, who led the analysis of the burst. "For the first time, we can put the limit [down to] the energy scale in which quantum effects would alter the geometry of space time."
The MAGIC time delay may be down to an astrophysical process where particles are accelerated to enormous energies within the hearts of galaxies. Follow-up calculations after MAGIC's 2005 result showed that is possible to produce flares that release lower-energy radiation before higher-energy radiation, according to MAGIC collaborator Robert Wagner of the Max Planck Institute of Physics in Munich, Germany. "I think what we can say for the time being is quantum gravity effects cannot be the dominant effect," he says.
Knockout blow?
The result does not necessarily strike a blow to quantum gravity. Only a subset of models predict the effect, and "while it seems reasonable to expect that the variation of the speed of light with energy is a sign of quantum space-time, there is no well developed theory of quantum space-time that cleanly makes this prediction," says Lee Smolin of the Perimeter Institute for Theoretical Physics in Waterloo, Canada.
What's more, it will require even more precise measurements to completely exclude the possibility that light may change its speed depending on its energy. "If there is an effect, the experiment is now at the threshold of scales where the effect is expected, and there is the exciting prospect that it could be discovered over the...next few years," Smolin says.
Journal reference: Nature (doi:10.1038/nature08574)
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Have your say
Universe's Expansion Changes The Planck Constant, Not Light Speed
Wed Oct 28 19:33:29 GMT 2009 by Polemos
http://eschatopedia.webs.com
Since the expansion of the universe increases the radius (the Compton wavelength) of a Planckian black hole (pixel), it also increases the Planck constant:
The Compton wavelength, λ, of a particle is given by
λ = h/mc
where h is the Planck constant, m is the particle's rest mass, and c is the speed of light.
***
E = hv (where E is the energy of a photon, h is the Planck constant, and v the frequency of the radiation).
It is apparent from the above equation that an increase in the Planck constant decreases a photon's frequency (in order to conserve the photon's energy). Therefore, we observe the increase of the Planck constant as the cosmological redshift.
Read more: http://eschatopedia.webs.com/endoflocality.htm
Universe's Expansion Changes The Planck Constant, Not Light Speed
Wed Oct 28 19:55:26 GMT 2009 by Polemos
http://eschatopedia.webs.com
According to Craig Hogan, director of Fermilab's Center for Particle Astrophysics in Batavia, Illinois, instead of 10^−35m, a Planckian pixel of space currently has the size of 10^−16m (the size of a free proton). This means that protons are Planckian pixels. http://eschatopedia.webs.com/electronandproton.htm
No wonder that light does not experience frequency-dependent retardation due to quantum-gravitational granularity of space.
Universe's Expansion Changes The Planck Constant, Not Light Speed
λ = h/mc
h and c are both constants so we only have m and λ: please can you explain the relationship between m and λ.
Also, I do not understand what you mean by "rest mass". I have seen this in many papers and never understood it, but I think it is quite important.
Universe's Expansion Changes The Planck Constant, Not Light Speed
Thu Oct 29 05:39:38 GMT 2009 by Polemos
http://eschatopedia.webs.com
E=mc^2 --> m=E/c^2
Energy is constant, so mass is constant too. The holographic principle says that λ is increasing over time (http://eschatopedia.webs.com/endoflocality.htm ). That is why in the right part of the equation λ = h/mc, some member is not a true constant. And this member is the Planck "constant," which is increasing with time.
***
The number of a particle's degrees of freedom is the particle's entropy. The rest mass of a particle inhibits the particle's freedom of movement. Therefore, the rest mass of a particle is the particle's negentropy--the nonuniformity of the particle's spatial distribution. The rest mass (negentropy) of a particle is the proportion between the Universe's radius (the particle's maximal possible entropy) and the particle's Compton length (the particle's actual entropy).
For example, a zero-mass particle becomes smeared out over the entire volume of the universe. The higher the mass of a particle, the smaller the volume it occupies. Read it here (after Equation 23.14): (long URL - click here)
Universe's Expansion Changes The Planck Constant, Not Light Speed
E=mc^2 --> m=E/c^2
We may be confusing constants and variables. C is probably a constant: so much so that Feynman eliminated C from his path integrals to make them simpler. Feynman always said that he would put C back into his equations if necessary but he never had to do this (as far as I know).
You say that E and m are both constants. They are in fact variables: one of them is the dependent variable and the other is the independent variable, depending on how you look at them. They may indeed be infinitely variable but I cannot be certain about this because I am no good with infinities.
You say that the Planck constant is not a true constant because it increases with time. If the Planck constant increases with time then it must be a variable; it varies (as you say) with respect to time. Or perhaps it is an untrue constant or even a partial variable?
I do not understand your definition of rest mass. Perhaps it would help if we contrasted rest mass with active mass.
As you know, mass is related to gravity. But it is the active mass that is the source of gravity and this active mass is not simply the same as (or proportional to) the energy, as implied by E=mc^2.
Active mass is the energy density plus the sum of pressures and this is what causes the inward acceleration of gravity.
Given this simple definition of active mass, how would you now define rest mass (which is even simpler)?
Here is a clue: the definition of rest mass does not involve entropy or negentropy or posentropy (as far as I know).
Use simple mathematics to explain your proposition, if it helps.
Universe's Expansion Changes The Planck Constant, Not Light Speed
I wouldn't recommend asking Polemos for further explanations, you will only end up more confused. Ultimately you could be as confused as him. Which would be a very sad fate.
Rest mass is simply the mass of an object at rest (not moving). Einstein's theory predicts that an object's mass increases as its velocity approaches the speed of light (and this has been measured and found to be in accordance with the theory).
Universe's Expansion Changes The Planck Constant, Not Light Speed
Fri Oct 30 22:29:17 GMT 2009 by Dennis
http://freetubetv.net
I looked at his page and it said something about how science is leading to the end of the world?
Universe's Expansion Changes The Planck Constant, Not Light Speed
Polemos misunderstands what expands as the universe expands.
The expansion of the universe only affects the distance between objects with no forces holding them together, the fabric of space-time gradually expands.
The "yardstick" used to measure distances between objects does NOT expand.
If the yardstick did expand along with space-time, then we would not see anything expand. An example will help understand this. Suppose space-time expands by 10%. Also suppose the yardstick used to measure the distance between distanct galaxies also expands by 10%. Then you'd always measure the same distance between distant galaxies.
The yardstick does not change. When the electron in hydrogen changes from the n=2 orbital to the n=1 orbital (the Lyman alpha transition), the wavelength of the photon when emitted is always 1215.668 angstroms. Once these photons are emitted, they get red-shifted over time by the expansion of the universe. But freshly emitted photons always have a wavelength of 1215.668 angstroms, because the yardstick does not change.
The yardstick is made of the fundamental constants of the universe, including the Planck constant, the speed of light, the mass of the electron, and the strength of the electromagnetic force. These constants are what determine the wavelength of newly created Lyman alpha photons. Physicists have done experiments to see if these constants change over time. So far, there's no reliable evidence they do change.
Another one of these fundamental constants is the strength of gravity. The Planck length is calculated from the strength of gravity, the Planck constant, and the speed of light, so it is also a yardstick.
I've heard some physicists argue that the Planck length is not a valid concept because of the holographic principle (which I won't get into). This is a topic of debate among professional physicists.
Polemos is not a professional physicist. No professional physicist argues that the Planck constant is expanding with the universe, because the professionals all understand the argument I'm making (I learned it from them).
Polemos may simply misunderstands physics.
Or he may be one of those megalomaniacs who:
1) Believes all professional physicists are wrong and only he's correct.
2) Professional physicists don't want to admit they're wrong, so they divert attention from themselves by calling him a crank.
3) Someday he'll be vindicated, and he'll be called the next Einstein.
Beware of what you read on the internet, especially in blogs.
Universe's Expansion Changes The Planck Constant, Not Light Speed
Thu Oct 29 08:50:17 GMT 2009 by Polemos
http://eschatopedia.webs.com
David: "The expansion of the universe only affects the distance between objects with no forces holding them together, the fabric of space-time gradually expands."
***
In Boltzmann's definition, entropy is a measure of the number of possible microscopic states (or microstates) of a system in thermodynamic equilibrium, consistent with its macroscopic thermodynamic properties (or macrostate). ((long URL - click here) )
That is why the Planck constant is a measure of the entropy of the vacuum ("the fabric of spacetime"). If the magnitude of an energy fluctuation of the vacuum is below the Planck constant, the fluctuation remains a virtual microstate, and does not become a macrostate--a real wave. The expansion of the universe increases the entropy of the vacuum--the Planck constant.
Universe's Expansion Changes The Planck Constant, Not Light Speed
Thu Oct 29 09:22:58 GMT 2009 by Polemos
http://eschatopedia.webs.com
The expansion of the universe increases the entropy of the vacuum--the Planck constant. Why? Because the vacuum is the universe's gravitational potential. As the universe expands, its matter becomes more sparsely distributed, and the gradient of the universe's gravitational potential becomes less steep. In plain words, the "fabric of spacetime" (the vacuum) becomes more slack and entropic.
Universe's Expansion Changes The Planck Constant, Not Light Speed
Can anyone consider a not expanding universe ?
"The expansion of the universe only affects the distance between objects with no forces holding them together"
There is a posibility that the universe its not expanding and that only the constants are changing.
The change of "yardstick" as in speed of light and speed of time can create the ilusion that the universe its expanding
Universe's Expansion Changes The Planck Constant, Not Light Speed
Thu Oct 29 10:31:40 GMT 2009 by Polemos
http://eschatopedia.webs.com
As I have explained in my post above, the Planck constant is a measure of the vacuum's entropy. More entropic = less compact (just compare a gas and a crystal of the same mass). That is why increase in the vacuum's entropy is equivalent to its expansion.
Universe's Expansion Changes The Planck Constant, Not Light Speed
Quick question based on the following...
"The expansion of the universe only affects the distance between objects with no forces holding them together, the fabric of space-time gradually expands."
Do any of these objects have 'volume'? If they do, space in regions with a higher density of these objects would be expanding at a slower rate then that in lower density regions.....could that (if true) result in the higher then expected velocities of stars further out from galactic centers?
Sounds like a silly question as space i suspect, must be present throughout any and all objects. I suppose that's another question.
Universe's Expansion Changes The Planck Constant, Not Light Speed
Thu Oct 29 12:33:50 GMT 2009 by Polemos
http://eschatopedia.webs.com
"could that (if true) result in the higher then expected velocities of stars further out from galactic centers?"
You are almost correct, Heath. It results in the higher then expected recession velocities of stars further out from the centre of galactic centers--the planet Earth.
***
Now let's tackle your second question.
Particles of matter are gravitational centres. Free vacuum is gravitational periphery. The entropy of particles of matter decreases at the expence of the rising entropy of free vacuum. At that, elementary particles exist on the substrate of vacuum and should become more entropic (magnified and blurred) together with the latter. Indeed, as the universe expands, the wavefunctions of individual electrons and protons become magnified and blurred (more entropic, old). But this is exactly why the totality of the electrons and protons becomes more interconnected, negentropic, younger and wiser:
"Reason is the rose in the cross of the present." (Georg Wilhelm Friedrich Hegel)
Read more: http://eschatopedia.webs.com/entropy.htm
If the universe is made up of quantum foam, planck masses etc, and we can measure such events over such huge distances, could the effect of the random walk, of energy being transfered from foam to foam over planck steps over billions of light years, the average position of photons should produce a ring around the measured location, but this would be an absolute radius ring at the point of detection, and so require a sensor of better than such physical accuracy to measure it?.. As in, if the average displacement from the point source was only a milimetre or so at the lens, mirror, could the Hubble resolve it?
If the random walk did occur, what would be the displacement after crossing the entire known universe, or would the displacement ever reach the radius of the universe, given slowdown on closed space, extended time, etc etc, and would this have other effects?
I am not a physicist but I've read some interesting articles on slowing down light dramatically by increasing a materals refactive index. Couldn't you take a very long optical cable or B.E. condensat and slow down the light passing through it and see who wins? My thought is if you adj the C variable this should make the Planck scale larger.
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