Light is always in Hammertime.
Just for a point of comparison, that’s roughly equivalent to a giant tortoise vs. the Concorde.
No speed other than c is ever innate to anything. There’s no reason you couldn’t have a neutrino sitting at rest relative to the Earth. If it’s got a lot of energy, it’s because some process gave it that energy.
I suppose you could say that it’s “innate” in the sense that, in the typical processes we know of by which neutrinos are produced, the neutrino ends up with a large amount of energy relative to the zero-momentum frame of the process that creates it. But it’s tough to compare that to the Oh-my-god particle: What’s the typical process by which a proton is produced? The vast majority of protons in the Universe date back to a time when our knowledge of the Universe is sketchy at best, and the production process of those protons was surely highly energetic. If anything, we could say that we observe slow protons only because external processes have acted to slow them down.
Knowing the velocity of propagation (VoP) for an electrical pulse in a cable or conductor is essential to using a time domain reflectometer (TDR). We normally test a cable to ascertain the VoP before working on it or performing measurements.
The major contributing factor for the VoP is the construction of the cable. The distance between the conductors and the insulating material used can make a huge difference. For standard electrical cables (i.e., cables that were not specially constructed to be used in scientific experiments or to achieve much faster current flow), the VoP ranges from about 72% to 88% of the speed of light. I’ve never worked on one that exceeded 90%, but I’m sure they exist.
Not to nitpick, but I would argue with that wordsmithing. This is just saying that the speed of light is subject to the laws of physics. But this is not the same as saying that it is arbitrarily constrained by material properties, like the energy level of a particle or the wave-propagation properties of a material. I was just trying to get across the idea that the speed of light in a vacuum is innate, fundamental to the nature of spacetime. You can’t tweak space or add energy to make light go faster – in effect, its speed is already infinite, since photons experience zero time and move with the speed of causality.
My vote is for the Oh-My-God particle:
The drift velocity of electrons in a conductor is on the order of millimeters per hour. The phase velocity of electrical current depends upon the construction of the cable and insulation, but it is on the order of 80% of c, which is fast enough to not matter for normal purposes but does result in enough latency for submarine communications cables that fiber optic cables are necessary for high data rate applications. (Using optical signals also provides substantially more bandwidth per cable than electrical signals.)
As a class of particles, neutrinos are probably a reasonable guess as the “next fastest particle”, but particles accelerated by the Penrose or Blandford–Znajek process can increase in momentum to any arbitrary fraction of c, and this is hypothesized to be a mechanism by which quasars continually produce supernova levels of radiation. On the other hand, the speed of neutrinos is limited to the energy of the beta particle it decays from and mass of the neutrino. You could, of course, accelerate a beta particle to any speed before it decays, but “second fastest thing” is going to be an arbitary selection of some object with mass being accelerated to c minus some infinitesimal amount. While the so-called “Oh My God particle” was moving very fast, statistically it is unlikely to a point of certainty that the Earth has encountered anything near the fastest particle in the universe.
Note that while we refer to c colloqually as “the speed of light”, it is actually the speed of propagation of interactions in Minkowski spacetime. All gauge bosons (the photon, the gluon, and the hypothetical graviton) and any other massless particles that may exist beyond the Standard Model of particle physics have to move exactly at c by fundamental nature.
Stranger
Hm… I did some more digging, and apparently there’s been a neutrino event detected with an energy of 2e15 eV. Given a maximum neutrino mass of ~1 eV (though I think there are tighter bounds than that, even, now), that means a gamma factor of 2e15, much greater than OMG’s 3e11. If you really want, you can work out to what that means as a speed, but at that point you’re writing so many nines that it’s much more sensible to just compare gammas.
The OMG particle had an energy of 3.2±0.9×10[sup]20[/sup] eV.
That proton could not only smash your window, it could also knock your grandmother’s framed family portrait off the mantelpiece and smash it to bits! 
But the thing about measure the speed of various objects and particles in the universe is that we’re always measuring their speed relative to some other reference frame. So some proton hits a detector going 99.999999999% of c. So that’s the fastest thing? No, because we can always say that the the whole goddam Earth was traveling at 99.9999999% of c, and it was the particle that was stationary.
So any measured speed of anything in the universe could always be higher or lower if we just change the reference frame. Unless that thing is traveling at c, in which case it doesn’t matter what crazy reference frame we use, we always measure it at c.
A neutrino emitted from the Sun is traveling really really fast relative to the Sun. But if we measure it relative to another neutrino emitted in the opposite direction, it’s traveling even faster. It doesn’t matter what we measure, there’s always going to be something faster.
I think the trouble is you’re conflating “physical” and “material”. There is no material constraint on the speed of light in a vacuum (since there is no matter involved). But, as you explain, there is a physical constraint on the speed of light in a vacuum–the physics of the universe permit no other speed.
And a rest mass (assuming it was a proton) of approximately 1e9 eV. The energy divided by the rest mass gives you the gamma.
In other words, the OMG particle had more energy than the highest-energy neutrino, but only because protons are much more massive than neutrinos.
For practical definitions of fast, I’d agree with OMG, because we can calculate how fast it was going. For more oddball situations…
AFAIK, Kamiokande demonstrated that neutrinos have mass and therefore can’t travel at c, but couldn’t calculate what the mass was. I don’t know if any more recent experiments got us any closer to a value, so it’s not really possible to say how close to c it can go. But, watch supernovae for long enough and you might find a super-OMG neutrino.
Cherenkov radiation. It may not be anywhere near 3e8 m/s, but being able to say “this particle traveled through air faster than the speed of light in air” is fast and cool.
With quantum effects, speed is probably closer to NaN than ‘very fast’, but quantum tunneling, and general effects like electron jumping between atomic orbitals, are traveling a non-zero distance in a very very very small time. Hawking radiation from the “photon travels faster than c to escape the black hole” point of view.
Under sort-of-illusionary speed, you have expansion of space and galaxy-sized pairs of scissors, where two objects move faster than c relative to a third observer, but each object itself is slower than c.
For slowest speed, I nominate ‘how long is it until lunch’.
Even if we can’t say precisely how fast that super-neutrino was moving, we can still say that its gamma factor was at least four orders of magnitude greater than OMG’s. Given that, I think that it’s probably safe to say that the fastest neutrino in the Universe is probably faster than the fastest proton in the Universe, even though we’ve (probably) never observed either.
Chronos, I know you’re too smart to forget Gallilean relativity, so I’m puzzled by your statements about one thing being “faster” than another. In some reference frame the proton is faster than the neutrino, and in fact in some reference frame the neutrino is standing still. So how can you talk about one thing being absolutely faster than another thing?
Would you be happier if I said “in any reasonable choice of reference frame”? Or “Any reference frame that anyone would ever use for any purpose other than making the notion of ‘motion’ seem absurd”?
I think Chronos is post padding now that he’s hit 70,000.
- Ducks and runs-
Note that beta decay and fusion aren’t the only way to make neutrinos. Whatever cosmic furnace is able to churn out OMG protons will very likely churn out mesons that will decay to produce OMG neutrinos of similar energies and therefore much higher speeds. In other words, it is difficult to imagine making crazy high-speed protons without also making even crazier higher-speed neutrinos at the same time.
What is the 2nd fastest thing?
Bad news.