What if the speed of light is NOT constant?

Thanks exchemist, you explained it beautifully!

 

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Oh really? I thought it was just a long-winded way of saying "I don't know".

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But seriously, I'm still hoping we may get a contribution from a proper physicist about these Bessel beams and how you can fool light- in free space - into taking a longer path than the most direct one.

 

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Well, in this case we aren't measuring the local speed of light directly, though I imagine that the experimenters put as many elements in place as possible so that they could get as close as possible to this measurement.

Any measurement over a finite distance is not local. But we can try to ensure that factors that might cause the speed over a finite distance to vary from the local speed are negligible.

 

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Was there an experiment done? My interpretation of the article was that these papers are mathematical only. It is barely possible even in principle to test the idea because you'd need the apparatus to be located in intergalactic space!

In any case, if I understood correctly that these papers are just calculations, not experiments, then they are single point "measurements".

 

I don't think that's either of the articles described in the OP.

 

Wouldn't our God Bothering friends and Creationists make some mileage out of this!

 

The two papers referenced by the article linked in the OP are both discussing how light interacts with the quantum vacuum or zero-point-field of empty space, actually I believe they go further and specify virtual particles... I have not read either yet, just glanced at them, I may or may not spend any real time.., but they are both available at arXiv, http://arxiv.org/abs/1301.3923 and http://arxiv.org/abs/1302.6165. Needless to say, since vacuum energy has not yet been proven, as more than theoretical, these papers must also be read as theoretical.

There are a couple of other papers mentioned in the next few posts that don't, at least superficially seem to be talking about the same thing.

Note: Only the EM spectrum of vacuum energy may be thought of as having any real counter part.., and then only if we consider all EM radiation as contributing to vacuum energy. But even then we have no experimental proof that EM radiation interacts with EM radiation.., i.e. Light interacting with light.

 

Yes I see. I was responding to the recent Glasgow experiment, which was the second of MR's references, and which Paddoboy picked up on. But you're right, the original reference was something else entirely.

 

You are absolutely right! I was thinking of a different thread.

 

Yes they do, because the title of this thread is What if the speed of light is NOT constant?

 

Fair enough, I didn't even look at that one. I really don't get the whole group vs phase velocity kick some physicists seem to be on right now. Seems to me like they are just tricks to get their names in a newspaper because reporters have no understanding of science.

 

Look up the word "context" in a dictionary, then go back and reread the article in the OP.

 

To end this thread and question of what if, what if does not apply, there is no what if's, regardless whether that by interference of c , can and does change the speed of light, the constant to sight of light we observe with our eyes is unaltered in empty space and remains at a constant to sight.
So regardless of the speed of light , we only see by speed differential of the constant c, and do not observe a speed because we are submerged in the speed and relative to light, we move through the light and it is our speed that effects the constant speed. Travelling into the light relative to the observer, the light is faster than an observer travelling away from the light, if the observer was travelling at c towards the light, the observer would observe the light travelling at c towards the observer, half the time equals twice the speed.
You observe by the speed of sight, being equal to the speed of light, the communication protocol of matter to the brain is of which is capable of transmitting messages modulated onto light waves through the constant equilibrium carrier signal to the brain. A low voltage differential signal received by our brains through the constant of the constant.
This is what none of you seem to understand.

 

I've read it. It says things like this: Some scientists are exploring the possibility that the speed of light actually changes due to the nature of the vacuum of space. Well duh, Einstein said that:

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LOL! If Einstein said to jump off a bridge, would you do it?

From the Bible: Mathew, Mark, Luke and Farsight~

And thus spoke Einstein to leap off a bridge, and the faithful did break their bones and die.

 

I think the Glasgow work is genuinely bizarre and interesting. It all hinges on these things called Bessel beams, which I gather do not spread out as they travel, and in which they have got the photons to follow a path that does not propagate 100% in the direction the beam is pointing in. Presumably they follow a spiral or a zigzag or something. Very weird, and they have actually timed the departure and arrival of photons and verified they take longer to arrive than if they took the straight path and travelled at c. It's true they mention group velocity, but I think the experiment was done in vacuo, rather than a dispersive medium, so there doesn't seem to be any reason why group, phase and front velocities would differ in this case, so far as I can see.

I have trouble getting my head round what a Bessel beam is. If I could understand that, I might be able to follow the rest.

 

No, clearly you didn't look up the word "context" because you are still ignoring the context. If you looked at the context, you'd see that you don't actually disagree.

 

Huh? I know what context means. And I'm not ignoring anything. The thread title is what it is, the article says what it says, and Einstein said what he said. Now go and read what he said. Stop trying to ignore it on specious grounds of "context". Oh, and here's another quote for you, from Irwin Shapiro:

"Because, according to the general theory, the speed of a light wave depends on the strength of the gravitational potential along its path..."

 

Farsight's problem is that he sticks to the fantasy version of Einstein that he has in his head. He refuses to learn the mathematics that Einstein used to express all his ideas and he refuses to look hard at anything, including context, that might shake his reverie.

 

No, Farsight's problem is he so desperately wants to know something you don't know. Whatever the history of his neurotic disposition, he is always eager to say things like "Ha, Ha! So you think you're smarter than Einstein?" Hoping it will make others cower.

Farsight is the sole executer of Einstein's will and he is the only one then that is able to forgive us of our sins.