We all know that light is the fastest thing in the universe. (And please don’t start an argument about that. Take it as a given.) So, what is the 2nd fastest thing? I’m thinking electricity. Has the speed of electricity been measured? How fast is it? Must be at least close to light, don’t you think? Any way to give it a boost so that it equals (or exceeds) light? That would be cool.
All electromagnetic radiation travels at the same speed, not just visible light.
The speed of gravity is the same as the speed of light, so tied for first, or tied for second, take your pick. The wave propagation speed of electricity varies with the medium, but can get up to 0.99c, so a close second. If you’re talking about the speed of an actual electron in a wire, that’s a lot slower.
Electrons in a wire are going to be way slower than random things flying around in outer space.
My WAG is some space radiation is the fastest non-light thing and it’s basically moving just short of the speed of light.
Does that mean radio waves and television transmissions?
yep
I’m going to put in for Neutrinos, which are so fast they are sometimes erroneously measured to go faster than light.
I’m pretty sure this thread is going to go way beyond my comprehension but I’ll try to hang in there. I’ve already learned something. Yay! Let’s hear it for fighting ignorance!
A comet has some good speed as it passes its sun.
The Oh-My-God particle, at 99.999999999999999999999510% of the speed of light.
Not even remotely in the same league.
The speed of time/gravity/light/EMR in vacuum is 3E8 meters/sec or 10,000 kilometers per second.
The famous Halley’s comet is going about 55 kilometers per second. About 1/200th the speed of time/gravity/etc.
Comets with longer orbits and longer periods can go much faster. So instead of 1/200th the speed of time/gravity/etc they’re going 1/50 or 1/30th the speed.
Still nowhere close.
Back to the OP: The magic about the speed of time/gravty/etc is that it is a fixed number. There’s nothing else in the universe like that. Any other physical motion or speed of propagation happens at a speed that depends to circumstances. So it isn’t sensible to talk about the “second-fastest thing”.
It might be possible to talk about the “second fastest combination of thing & circumstances”. But even then we get into questions about measurement accuracy, etc.
E.g. the speed of light propagation through fiberoptic glass is measurably obviously significantly slower than the speed of light propagation through a true idealized vacuum. But what if we built slightly better glass that halved the difference? And improved it again to halve the difference again? How fast is "as fast as light in vacuum (the “official c”), less some teeny tiny amount we can barely detect?
All those other things are physically constrained. The speed of light (in a vacuum) is not. That’s a really fundamental difference. The speed of light isn’t some arbitrary “speed”, it’s the rate at which causality propagates in spacetime, and as such is one of the constants of the universe. Lots of things travel slower than light, but those are limited by physical properties and not universal constants. For example, the propagation speed of light in various media other than a vacuum, or the speeds to which subatomic particles can be accelerated in particle colliders. But those aren’t particularly interesting limits. They depend on arbitrary material properties or available energies.
I’ll give you a moment while you facepalm.
Meanwhile, I also immediately thought “neutrinos” when I saw the thread title. Yes, you get oh my god particles under very extreme circumstances, but your garden variety neutrinos travel at just a whisker below the speed of light.
Nice catch. Thanks.
:smack: 3E8 meters/sec = 3E5 km/sec = 30,000 kilometers/sec. So the rest of my numbers are mis-stated by a factor of 3.
One more time: Edit upon edit upon timed out edit:
Nice catch. Thanks.
:smack: 3E8 meters/sec = 3E5 km/sec = 300,000 kilometers/sec. So the rest of my numbers are mis-stated by a factor of 30.
I had some alarm bells in my head as I was typing. That 1/200 number felt too big. But like an idiot I just ignored the alarm bells & hit [submit].
Halley’s apehelion isn’t 1/200th of c. It’s 1/6000th.
Must be time for my sabbatical from the 'Dope. That’s 4 dumb mistakes in utterly unrelated posts in the last 4 days.
I would vote for neutrinos as well. Indeed they would seem to fit the OP’s question as perfectly as we know.
OTOH there has been some suggestion that due to the nature of the vacuum, there is an intrinsic very slight roughness to the path that photons take through space, so even though they travel at c, they do so on a very slightly longer path, and if measured at macroscopic scales the apparent speed is very slightly less than c. I’m not sure that this could not however be more akin to suggesting that the vacuum has a refractive index ever so slightly larger than one.
We can’t actually compare the speed of neutrinos to the speed of the Oh-my-god particle. In both cases, what we actually measure directly is the energy. If you know the mass of the particle and its energy, then it’s straightforward to calculate its speed. We’re pretty sure that OMG was a proton, so we can use the mass of a proton (which we know very well) to calculate its speed. But we don’t actually know the mass of the neutrino. We have an upper bound for the mass, so we can calculate a lower bound for the speed, but they might be much, much lighter, and so must be going even faster to reach that energy.
One can in principle turn that around, by taking neutrinos that have traveled a very long distance, and use the difference in their arrival time, combined with their energies, to determine their mass. This has been done with the neutrinos from supernova 1987a. But the error bars in the measurements were too large, and so you can get better results from other experiments, and we haven’t been able to reproduce the measurement, since we haven’t had any sufficiently distant sources of neutrinos since 1987.
How about the expansion of the universe itself?
But whatever the speed of a neutrino is, it is fast, and it is innate. To get an “oh my god” particle you have to take a common slow particle and stick it in a gigantic natural accelerator. So can you say that anything other than a neutrino travels at closer to the speed of light without outside help?
The speed of light in a vacuum is physically constrained. It may not vary from the constant c.