Does this mean that some particles can accelerate to a speed faster than the speed of light?
I didn’t read it that way. The speed of light in and of itself isn’t that important. It is known that light travels at different speeds in different mediums. Researchers have been able to slow it down to a crawl or even stop it in recent years.
What is important is the constant C (the speed limit of the universe). Light is one of the things believed to travel at C at least in a vacuum but this article is saying that we may not know as much about vacuums as we thought. A vacuum may not be just the absence of anything but consist of quantum particle pairs that may not always be the same. I believe they are saying that conditions within a vacuum may vary and therefore so would the light that travels threw it. C itself would not be violated. The differences would slow light down but at varying levels. These differences would still be incredibly tiny but may be measurable with the latest equipment and might be importance for theoretical physics but not in everyday practical terms.
There are two ways to talk about the speed of light, and they usually get confused.
Call C the constant that is used in E=MC[sup]2[/sup]. It is fixed and independent of nature.
Call c the local speed of light, the speed at which light moves through a physical object. This varies with every possible transparent object.
We know that c is always < C. Shine a beam of light through a diamond and it will slow considerably. Shine it through the vacuum of interstellar space and it will slow down only by a tiny bit, depending on how many particles still remain.
That article appears to say that creation of virtual particles from the vacuum energy has an effect on light that is measurable even if all other particles have been removed. You can use that to measure how many particles actually remain in a supposed vacuum.
But nothing is accelerating faster than C. It’s all about local speed, c.
No.
It means the speed of light may be slowed by 1/several 100 millions of a second, not due to its intrinsic nature,
but due to interference from particles whose presence prevents there from being a true vaccum.
Ten quatloos says that this research is rescinded, disproven, or otherwise superseded within a year. Probably six months.
This could be huge. It could tell us the nature of particle pairs in the zero point field and their density distribution. That would give us mass. From that would determine to what extent if any the quantum vacuum contributes to either dark energy or dark matter. Dark matter obviously because of the additional mass, but dark energy since the particles are particle-anti-particle pairs which annihilate.
Is there any way of calculating C from other measurable constants and comparing the observed c to it?
I don’t get the distinction. The speed of light (abbreviated in all texts as “c”) is approx. 186,300 miles per sec in a vacuum. However, there is no absolute vacuum. Even the “vacuum” of outer space has virtual particles, which, as you note, slightly lowers the speed. The denser the medium through which light travels, the greater the effect on its speed. “C” stands for “constant” because its speed is not relative to the movement of anything else, not because it has a constant speed in all mediums.
As deltasigma pointed out, the importance of the article is that it may be a lead in to determine the nature of dark matter and dark energy.
Could you break this down a little? What does this have to do with mass, for instance? And how exactly do you think dark energy and matter comes in at all?
Ah, you’re probably referring to the idea that vacuum fluctuations don’t necessarily have to be conceived of as virtual particle pairs perhaps?
However we know that vacuum energy contributes to the mass of particles. In fact, it makes up 99% of it.
This doesn’t really say that. Basically, taking into account virtual quark-antiquark pairs improves the numbers from being accurate up to 90% to being accurate up to 98%:
And this is no surprise. The idea is basically that most of the mass of a composite particle is contained in its binding energy; those calculations merely get a better estimate of this binding energy. And I’m afraid I still don’t see what any of this has to do with the vacuum speed of light, or dark matter/energy…
But that binding energy exists in a state of constantly annihilating sea quarks.
Meaning what for dark matter or energy, and depending how on the speed of light?
That vacuum fluctuations have mass, energy or both.
I read the paper, and while it was obviously beyond my undergraduate physics level, I was struck by a number of things.
If different photons in a beam travel at different speeds because they interact with different numbers of fermion pairs along the way, how does a laser remain coherent? How can interferometry in general work?
There’s a line in the paper that caught my eye: “this mechanism relies on the notion of an absolute frame for the vacuum at rest”. Hmm. Aether?
It appears that the authors are proposing a form of interaction between photons and these quantum-fluctuation fermion pairs that operates by some novel mechanism not seen before. Is that a fair assessment?
I’m just guessing here but maybe the issue is that the differences in speed are so vanishingly small that they couldn’t be detected previously. From the OP link -
This is a somewhat speculative research paper, yet to published and certainly unverified experientially.
C is not the speed of light. C is the speed limit of the universe. When in a vacuum, light travels at C, when not in a vacuum, light travels at a speed less than C. If the researchers have discovered that light travels slower than C through a vacuum, it has no effect on the nature of C. Therefore although it may be possible that there is some particle that can travel faster than light through a vacuum, it does not mean that the particle can travel faster than C through a vacuum.
The density of the vacuum nearby isn’t precisely what determines c.
c is related tot he permeability and permittivity, which makes sense as the e/m wave is affected by the e and m properties of the material…
This is probably a very dumb question. The variation is tiny. Is it so tiny that it isn’t meaningful even at large distances? Could it affect, for example, calculations of the size of the universe or the distance of very distant astronomical objects?