I once saw a video where a guy sucked his own dark.
Advanced Photon Source at Argonne National Laboratory
Electrons are injected into the booster synchrotron (photo below), a racetrack-shaped ring of electromagnets, and accelerated from 450 MeV to 7 billion electron volts (7 GeV) in one-half second. (By comparison, the electron beam that lights a TV screen is only 25,000 electron volts.) The electrons are now traveling at >99.999999% of the speed of light.
There are good reasons to believe that [post=6060775]gravity propagates at c[/post]. We do not have incontrovertible proof of this currently, owing to the weakly interacting nature of gravity, but we have every expectation of it.
The “second fastest thing” is a limit problem; any massy object can be accelerated asymptotically, but never reaching, c. And light, in fact, may not actually be the fastest thing in the universe. Setting aside hypothetical and completely unvalidated tachyonic particles, it can be firmly established that space itself can “stretch” faster than c and, if current speculations are correct, will do so to the point that individual particles will accelerate away from each other, surfing on waves of expanding space some time in the far, far, far future.
So, actually, light may be the “second fastest thing in the universe”; a runner up to the continuum itself. As Donald Kaufman would say, “Isn’t that fucked up?”
Stranger
How often does one get the opportunity to say a line like that?
Well played, my good man!
It’s supposed to place a speed limit on them, but there appears to be a flaw somewhere in the theory. Cosmic rays are detected with energies significantly higher than the GZK cutoff, and with no known source for them. There are myriad explanations for how this occurs, ranging from unknown sources close enough that a few particles survive the GZK limit, to particles getting diverted from known sources, to modifications of relativity at very high energies.
As for neutrinoes, it’s actually possible that the neutrinoes from SN1987a travelled on average faster than the light did, since space is not (quite) a perfect vacuum, and light therefore will travel through space at slightly less than c. The neutrinoes were also travelling at less than c, of course, but without knowing the exact mass of the neutrino (all we currently have is upper bounds), we can’t know just how much less than c they were moving at.
Wouldn’t there be pretty much a dead heat for second-fastest thing around the event horizons of black holes? My (admittedly limited) understanding was that the event horizon was the point at which the escape velocity exceeded the speed of light. Which implies that anything that fell into a black hole would be accelerated as close to the speed of light as you can get without achieving it.
As I understand things, we measure the velocity of distant objects through their interaction with EM waves. We see them or we bounce EM waves off them or they emit EM waves. So we can’t ever measure any velocity greater than the velocity of the EM waves. If that’s the case, how can this theory of particles moving away from each other in a space that’s expanding faster than light be tested?
All good answers – Neutrinos in a vacuum, Light in a sparsely populated vacuum, electrons at LEP, assuming that you buy Relativity without any possibility of a loophole.
Faster than light? hmmmm,
- Tachyons, should they exist, might certainly travel faster than c.
- Should anti-gravitons or solitons exist, they might allow other things to locally travel faster than c.
- Should instantons really exist or EPR quantum mechanical effects really provide a situation, other things might travel faster.
There are a million theories about Relativity loopholes – use google, there are far too many to mention here. 
By definition, if tachyons exist then they travel faster than light.
Both instantons and EPR correlations are now, in fact, rather conventional aspects of contemporary physics that are universally accepted by the professionals. Neither is thought to be an example of “faster than light travel” in any sense that violates relativity. “Spooky” yes, contrary to relativity no.
(I presume that it’s the connection with quantum tunnelling that’s prompted the reference to instantons. Tunnelling can give rise to odd, seemingly paradoxical effects, but the consensus is that the phenomena are consistent with relativity.)
:rolleyes: [Momentary hi-jack]
We agree then - my humility was laid too thick.
I don’t remember the last time I or anyone I know took instantons as more than a curious concept-patch that would need replacing later.
Einstein was a genius, but certainly not God. I expect that more loopholes [that will possibly not violate the fundamentals of Special Relativity (eg EPR Paradox)] will be discovered as time goes on.
As the fictional character from Star Wars, Han Solo once said, “It’s all alot of simple tricks and nonsense”.
That’s physics, right?
Yes, yes, so I am an experimentalist, give me a break.
And Bonzer, I must kneel to your knowledge of the specifics of theoretical Physics, otherwise.
Don’t be too hard on yourself, Citizen Bob - you know plenty of theoretical Physics. It’s not like you take different courses or something like that. It’s all the same thing.
Experimentalist are Physicists, too!
Me. Having sex.
Belgium! you beat me to it 
[QUOTE=KlondikeGeoff]
The Dark Sucker Theory
Oh thank you KlondikeGeoff!
That is one of the funniest things I have read in a long time.
did you write that? Way to go!
What’s the second fastest thing in the universe?
A shadow. If you wave a flashlight in front of your face at night, the shadow can cross the entire milky way in a second. And when you consider the stars beyond, it will span the universe in that time.
Here’s another link to the ultra-high energy cosmic rays: