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.