Skip to comments.Physicist suggests speed of light might be slower than thought
Posted on 07/03/2014 11:28:55 AM PDT by SeekAndFind
Physicist James Franson of the University of Maryland, Baltimore County has captured the attention of the physics community by posting an article to the peer-reviewed New Journal of Physics in which he claims to have found evidence that suggests the speed of light as described by the theory of general relativity, is actually slower than has been thought.
The theory of general relativity suggests that light travels at a constant speed of 299,792,458 meters per second in a vacuum. It's the c in Einstein's famous equation after all, and virtually everything measured in the cosmos is based on itin short, it's pretty important. But, what if it's wrong?
Franson's arguments are based on observations made of the supernova SN 1987Ait exploded in February 1987. Measurements here on Earth picked up the arrival of both photons and neutrinos from the blast but there was a problemthe arrival of the photons was later than expected, by 4.7 hours. Scientists at the time attributed it to a likelihood that the photons were actually from another source. But what if that wasn't what it was, Franson wonders, what if light slows down as it travels due to a property of photons known as vacuum polarizationwhere a photon splits into a positron and an electron, for a very short time before recombining back into a photon. That should create a gravitational differential, he notes, between the pair of particles, which, he theorizes, would have a tiny energy impact when they recombineenough to cause a slight bit of a slowdown during travel. If such splitting and rejoining occurred many times with many photons on a journey of 168,000 light years, the distance between us and SN 1987A, it could easily add up to the 4.7 hour delay, he suggests.
If Franson's ideas turn out to be correct, virtually every measurement taken and used as a basis for cosmological theory, will be wrong. Light from the sun for example, would take longer to reach us than thought, and light coming from much more distant objects, such as from the Messier 81 galaxy, a distance of 12 million light years, would arrive noticeably later than has been calculatedabout two weeks later. The implications are staggeringdistances for celestial bodies would have to be recalculated and theories that were created to describe what has been observed would be thrown out. In some cases, astrophysicists would have to start all over from scratch.
Explore further: Does light experience time?
More information: Apparent correction to the speed of light in a gravitational potential, J D Franson 2014 New J. Phys. 16 065008 DOI: 10.1088/1367-2630/16/6/065008 . http://iopscience.iop.org/1367-2630/16/6/065008/
The effects of physical interactions are usually incorporated into the quantum theory by including the corresponding terms in the Hamiltonian. Here we consider the effects of including the gravitational potential energy of massive particles in the Hamiltonian of quantum electrodynamics. This results in a predicted correction to the speed of light that is proportional to the fine structure constant. The correction to the speed of light obtained in this way depends on the gravitational potential and not the gravitational field, which is not gauge invariant and presumably nonphysical. Nevertheless, the predicted results are in reasonable agreement with experimental observations from Supernova 1987a.
I’m so fast that last night I turned off the light switch in my hotel room and was in bed before the room was dark.
Methinks the author makes it much more dramatic sounding than it really is. 4.5 hours over 164,000 light years? What is the percentage error?
Either that, or our propulsion systems have gotten a LOT faster
If its 168,000 light years away, then doesn't that mean that it exploded 168,000 years before we became aware of it?
This is making my head hurt.
Damned global warming.
This just goes to show that, “It’s later than you think.”.
It’s worse than that: the 168,000 light years distance estimate is based on... yep: light.
That difference would be HUGE as it pertains to cosmological constants, the math behind so many theories.
We are talking vast distances here and just that much of a difference would cause many theories to be tossed out. It’s isn’t the fact that the percentage is small because on a grand scale small becomes large ... it is the fact that there is a difference at all.
You just blew my mind...
I remember my physics teacher telling me there was an error factor in e=MC2. As I recall it was up to 5% that they couldn’t quite find.
So if you could really slow light down you could just walk to the next galaxy.
Is it important to know? Absolutely. Is the reason for the photon delay important to know? Sure is. Will it destroy all known human knowledge of the universe to date? Hardly.
So if the Sun blows up, we’ll know about it in 8 minutes and 22 seconds, rather than 8 minutes and 20 seconds. Phew...I feel much better now. The extra two seconds will really make a difference in my ability to make it to my shelter. /s
The theory of general relativity suggests that light travels at a constant speed of 299,792,458 meters per second in a vacuum.
That would be the Special Theory of Relativity NOT General Theory of Relativity.
If such splitting and rejoining occurred many times with many photons on a journey of 168,000 light years,
There's no IF. Quantum Field Theory unequivocally says this happens.
the distance between us and SN 1987A, it could easily add up to the 4.7 hour delay, he suggests.
And, although the journalist is breathlessly reporting this as an earth-shattering cataclysm, this represents a relative error of about 3 x 10-9. The error in the length of the meter is on the order of 10-10 so this is not that far from the error in absolute measurement. And as for consequences? Well, just for example, it would mean that the universe is potentially about 10 c-yr smaller than believed, which is ~45 bn c-yr in diameter. That number itself has only two significant digits, so an error in parts per billion represents NO CHANGE whatsoever.
Nearer at hand, the Sun is about 500 c-sec away. This order of correction would cause light to reach us all of 1.5 microseconds later [in vacuum.] Since the intervening space is not vacuum and is not even uniform, nor is the distance to the earth's surface, we could not measure this change in any meaningful way.
Finally, I'm a tad confused about the claim that this is "related" to the fine structure constant: on the one hand, of course it is, as are all relativistic electromagnetic corrections. On the other hand, the FSC [α] is ~1/137, which is many orders of magnitude larger than the error actually claimed...
Nope. It wouldn’t.
1987a has been thoroughly studied and the difference in time between the arrival of neutrinos and photons is understood. It should be noted that the author of this new theory is not an astrophysicist.
Yeah, well there was construction near Mars that had everything merging into one lane.
Ever since Obama slapped that tax on tanning beds, light has lost a step.
I dunno. It gets here pretty early in the morning.
Not only that, but how do they know the exact moment, where time = 0, that the explosion occurred? Saying that it took place in February 1987 doesn’t cut it.
Now it will take even longer to get to Cape Cod.
That story was first told by or about Cool Papa Bell:
Numerous stories are told of his feats on the basepaths. Many no doubt are true, such as consistently hitting two hoppers to the infield and beating the throw to first for a hit, going from first to third on a bunt, scoring from second on a sacrifice fly, stealing two bases on one pitch, and once scoring from first base on a bunt against Bob Lemon and a team of major league all stars. Other stories are simply colorful exaggerations. Such accounts have Bell hitting a single up the middle and being declared out when hit by his own batted ball as he slid into second base; and, of course, the most repeated story of how he could switch off the light and get into bed before the room was dark.
I believe that this finally explains why when you need your flashlight, it never works. All those photons have decayed.
Or is it possible that our theories about how light emerges from the last gasp of fusion from the supernova is wrong and it takes hours longer to make it through the star's outer shell?
That's a discrepancy of one part in 3.13 billion - an incredibly huge discrepancy, considering the precision to which this important fundamental constant has been measured.
Having said that: I suspect that there is a logical explanation.
The photons were stuck in traffic.
Where’s the picture of Hillary Clinton exclaiming, “What difference does it make?”
Nor was the author of my post, at one time a condensed matter theorist who makes no pretenses to expertness in cosmology. My comment did not deal with the origins of the discrepancy so much as the claims made that -- whatever their provenance -- these were potentially earth shattering discoveries.
As for the well-understoodness, is the delay accounted for entirely by the fact that it takes light from the core substantially longer to propagate to the surface than the weakly interacting neutrinos?
Probably just speedometer error from running the wrong tire size.
See, among many places, http://en.wikipedia.org/wiki/Virtual_particle.
The speed of light and second are now DEFINED, so you can no longer correctly say the "error in measuring the speed of light." But what amounts to the same thing is the length of a meter, which has been measured with an error of about 1/10 of this error. So larger than we would expect, but not incredibly large. And whether it would have cosmological significance, where most numbers [which are not just SWAG] range from order of magnitude estimates to no better than two significant figures is very doubtful.
Does the special theory actually cite a number like that, or does it leave everything in terms of c?
Here's one of the very first serious physicists' take on the matter:
"The speed of light, if not instantaneous, is extraordinarily rapid." -- Galileo
The symbol "c" itself was not used in Einstein's paper on Special Relativity. He used the symbol "v."
First, he applies the principle of relativity, which states that the laws of physics remain the same for any non-accelerating frame of reference (called an inertial reference frame), to the laws of electrodynamics and optics as well as mechanics. In the second postulate, Einstein proposes that the speed of light has the same value in all inertial frames of reference, independent of the state of motion of the emitting body.
I knew that....(must save face, must save face) LOL! I had no idea the time difference was that small. Thanks for the education my friend.
I just want to see his proof.
I suspect that you are not remembering entirely correctly. In any reaction, there is an "error factor" in that some of the mass goes missing. No one can find that missing mass.
Then Einstein came along, and in 1906 said that the missing mass no longer existed, it was converted into a burst of pure energy, by E=mc2.
By the way, very little mass goes missing in most reactions, but it is significant in nuclear reactions. More missing mass means more energy is produced.
Nobody could find it because until we had nuclear weapons nobody could measure it. Einstein predicted it, but in a typical chemical reaction it's so small it would never have been missed. For example, the binding energy of a water molecule is about 6 eV, whereas every nucleon has a mass of around 1 GeV [I'm going to do some rounding to make the math very simple.] For H2O, the molecule has a mass of (2 x 1 protons Hydrogen + 8 x 1 protons, Oxygen + 8 x 1 neutrons Oxygen) GeV + 10 * 0.5 MeV [for all the electrons]. Throwing away the electron mass of 5 MeV as insignificant to the calculation, the "missing" mass of bound hydrogen and oxygen in water is 6 / (18 * 10 9) or about 3 * 10-10 less than hydrogen and oxygen constituents. We can't really measure three parts in ten billion of mass, especially when the isotope balance accounts for a lot more mass than that all by itself.
You can re-do the calculation for something like high explosive, or gasoline, which have much higher energy densities and therefore much more binding energy, but it doesn't change things by more than a factor of about 10.
So 5%? No. More like 300 millionths of a percent.
And incidentally, even for nuclear reactions, you don't get 5%. For a typical nuclear fission, say 235U, you have [to the same order of rounding] about 235 GeV [the actual number is around 218 GeV] in the bound nucleus. When it fissions, you get around 200 MeV. So that represents a binding energy of about 200/235000, or 0.085% of the mass would go "missing" as energy.
This entirely a function of how much stronger the strong nuclear force [which binds nucleons] is than the electromagnetic force, which binds molecules.
I've been saying that all along but the guys in the bar simply laughed at me.........
Perhaps scientists are not accounting for a property that everything in the universe possess. Age.
The older something gets, the slower it gets. 168,000 light years will make anything age, and get slower, especially after such a long trek, which would make anything decay and slow down.
Thank you! That’s wonderful history that I had no idea about. I appreciate it.
So the stars are actually FARTHER away, not closer?
Just didn't want some "layman" (snark) to dismiss it as being entirely insignificant. But my hyperbole was admittedly inappropriate.