Can someone explain light accelerating past the speed of light?

[danzibr]

So recently I heard about the possibility of light going faster than the so-called speed of light, 3*10^8 m/s or 186,000 mi/s. Has anyone heard anything about this? I tried google but was unsuccessful.

And where does the 3*10^8 m/s come from, anyways? How certain are we that that really is the speed of light?

[Kindablue]

CERN's OPERA experiment (http://en.wikipedia.org/wiki/Faster-than-light_neutrino_anomaly), I'm guessing.

[Tonal Architect]

As far as I know, most of our current understanding of physics comes from mathematical models, which, from time to time, prove to be obsolete. The models will usually evolve beyond our ability to observe phenomena that validates them, also.

I'm not too familiar with heavy math, so while people can explain the model in layman language, in order to truly grasp how they work, you'll need to go through some numbers. Or perhaps, a lot of them.

[Bovine Colonel]

So recently I heard about the possibility of light going faster than the so-called speed of light, 3*10^8 m/s or 186,000 mi/s. Has anyone heard anything about this? I tried google but was unsuccessful.

And where does the 3*10^8 m/s come from, anyways? How certain are we that that really is the speed of light?

The "light" in question is not light, but neutrinos.

And the 3 * 10^8 m/s value comes from lab testing. Shine some light a heck of a distance away, see how long it takes for it to come back.

[JCarter426]

Aye, it was an error. For the record, it was neutrinos, not light (photons); neutrinos are tiny particles that have no electric charge and barely react with anything. They're a bit of a wild card, so while the results were surprising they weren't entirely unbelievable... so of course when it turned out to be an error, there was much disappointment.

As for the speed of light, it's simply a universal constant that has been measured, much like absolute zero. We're pretty sure it's correct.

EDIT: Bah, too slow. :smalltongue:

[Tavar]

And where does the 3*10^8 m/s come from, anyways? How certain are we that that really is the speed of light?

Note, that's its speed in a vacuum. Different mediums give different values.



Aye, it was an error. For the record, it was neutrinos, not light (photons); neutrinos are tiny particles that have no electric charge and barely react with anything. They're a bit of a wild card, so while the results were surprising they weren't entirely unbelievable... so of course when it turned out to be an error, there was much disappointment.
Did they actually prove that it was a mistake? I hadn't heard this.

[pffh]

Aye, it was an error. For the record, it was neutrinos, not light (photons); neutrinos are tiny particles that have no electric charge and barely react with anything. They're a bit of a wild card, so while the results were surprising they weren't entirely unbelievable... so of course when it turned out to be an error, there was much disappointment.

As for the speed of light, it's simply a universal constant that has been measured, much like absolute zero. We're pretty sure it's correct.

EDIT: Bah, too slow. :smalltongue:

Was it proven that it was an error? I thought they had some ideas about what could have caused it to be an error but were still working it out and waiting for the results from another accelerator.

[Kindablue]

As far as I know, most of our current understanding of physics comes from mathematical models, which, from time to time, prove to be obsolete. The models will usually evolve beyond our ability to observe phenomena that validates them, also.
Models based on experiments, yes. The models evolving past the facts that we have from those experiments allow us to predict how experiments that we haven't even done yet will go; and when we're right, it makes the model stronger. This is why the Higgs boson is in the news so much. It should exist according to the Standard Model, but that's just a prediction that hasn't been verified yet.


I'm not too familiar with heavy math, so while people can explain the model in layman language, in order to truly grasp how they work, you'll need to go through some numbers. Or perhaps, a lot of them.

We did something like this in high school. (http://www.physics.umd.edu/icpe/newsletters/n34/marshmal.htm)

[JCarter426]

Did they actually prove that it was a mistake? I hadn't heard this.

Was it proven that it was an error? I thought they had some ideas about what could have caused it to be an error but were still working it out and waiting for the results from another accelerator.
I thought it was a sure thing, but I haven't been following it very closely, mostly because of the flood of mockery from the antiscience crowd. As I recall, they're sure it's wrong, but there's more than one thing that could be causing it to be wrong. One of the possibilities is a lose cable, leading to said mockery ("scientists forget to plug it in cable" and such nonsense).

[Kindablue]

I thought it was a sure thing, but I haven't been following it very closely, mostly because of the flood of mockery from the antiscience crowd.

It was an error. (http://www.nature.com/news/embattled-neutrino-project-leaders-step-down-1.10371)

[AsteriskAmp]

Wasn't the metre defined in function of the speed of light and the definition of a second as the half life of some isotope?

Which in turn means you get shorter the more light speeds up...

[Riverdance]

Was it proven that it was an error? I thought they had some ideas about what could have caused it to be an error but were still working it out and waiting for the results from another accelerator.

What I heard on NPR was that the results indicating faster than light particles were the result of a loose wire.

[Starwulf]

Correct me if I"m wrong, but isn't there a fairly simple experiment you can do with mirrors and a few other things and measure fairly accurately the speed of light? I seem to remember reading something to that effect a few years ago.

[Knaight]

Correct me if I"m wrong, but isn't there a fairly simple experiment you can do with mirrors and a few other things and measure fairly accurately the speed of light? I seem to remember reading something to that effect a few years ago.

That is among the ways it has been measured. The oldest variation of this I'm familiar with is shining a light at certain intervals a mirror a very long distance away, so that it comes back to a spinning object with tiny holes in it. The rate at which said object is spinning when light does and doesn't get through the holes can inform as to the speed of light, though this isn't in a vacuum. Modern experiments work in other ways, so on and so forth.

In short, we have a pretty good idea as to the speed of light in a vacuum, much as we have an idea as to the rate of acceleration due to gravity on earth, they've been tested time and time again, and we get results.

[Starwulf]

That is among the ways it has been measured. The oldest variation of this I'm familiar with is shining a light at certain intervals a mirror a very long distance away, so that it comes back to a spinning object with tiny holes in it. The rate at which said object is spinning when light does and doesn't get through the holes can inform as to the speed of light, though this isn't in a vacuum. Modern experiments work in other ways, so on and so forth.

In short, we have a pretty good idea as to the speed of light in a vacuum, much as we have an idea as to the rate of acceleration due to gravity on earth, they've been tested time and time again, and we get results.

Cool! Thanks for the verification on that, was worried I was crazy or something for saying that :).

[Reluctance]

Wasn't the metre defined in function of the speed of light and the definition of a second as the half life of some isotope?

Which in turn means you get shorter the more light speeds up...

They had nowhere near the precision needed back when the meter was defined, much less the second. The meter was originally supposed to be some fraction of the radius of the earth.

Which they got wrong, leaving the basis of the metric system as some completely arbitrary value.

They used to use very carefully maintained rods and weights as the standards. Ever since science has been able to measure such things with precision, it's used more abstract measures that anybody in any sufficiently stocked lab can test.

[Douglas]

The current definition of a meter is expressed using the speed of light.

The definition of a second does use atomic phenomena, but nothing so statistical (and thus dependent on measuring averages over many atoms) as a half-life. Specifically, it is "the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom."

[factotum]

Wasn't the metre defined in function of the speed of light and the definition of a second as the half life of some isotope?


The metre is currently defined as a fraction of the speed of light in a vacuum, so no, it doesn't change depending where you are. As for the second, it's not defined in terms of a half-life--given that you can't really measure a half-life accurately, this isn't too surprising. The actual definition is:

"the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom".

So, it's basically determined by the frequency of radiation from an excited atom.

[Ravens_cry]

Aw, I was hoping Einstein would be dethroned.
Don't get me wrong, he was a pretty nice guy (though rather a lech'), but it would have been nice to know that there is more of the game left to discover.

[Reluctance]

There's always more left to discover.

But, just like Newton wasn't dethroned as hard as some people like to say - his equations still work well for slow, medium-sized, medium-mass objects), Einstein's equations work well for what they're designed for. They'll start to crack when we find some newer, weirder edges of reality.

Anyways, we can already break C in theory. It's just that one form can't go any slower, while the other leaves you cut off from the rest of the universe. Like I said. Newer, weirder, funner edges of reality.

[Killer Angel]

Einstein's equations work well for what they're designed for. They'll start to crack when we find some newer, weirder edges of reality.

Pretty much.
For example, Einstein himself got lot of issues with quantum mechanics. Which is weird.

[Ravens_cry]

Pretty much.
For example, Einstein himself got lot of issues with quantum mechanics. Which is weird.
Oh yes. Since there is only one universe, it seems logical there should be one set of rules to explain it all.
Relativity has it's own weirdness.
Consider, that time does not pass for a photon. If you were a photon, time would not move from your perspective.

[Dr. Bath]

It was an error. (http://www.nature.com/news/embattled-neutrino-project-leaders-step-down-1.10371)

OPERA and a few other labs are still checking it though. Just in case.

Because, you know, neutrinos be crazy.

[Iruka]

I recently read something in a journal about accelerated light. Though it was about light traveling through matter. I'll look it up when I get home.

[huttj509]

Oh yes. Since there is only one universe, it seems logical there should be one set of rules to explain it all.
Relativity has it's own weirdness.
Consider, that time does not pass for a photon. If you were a photon, time would not move from your perspective.

If you were a photon, you would have nothing to perceive WITH, and thus have no perspective.

But yeah, we teach various models that we know are not Right, but work well for what they work for. The trick is learning when various things break down.

Newtonian mechanics and the Bohr model of the atom are two that immediately come to mind.

BTW, that marshmallow experiment for measuring c using microwaves is AWESOME. I love experiments that approach things from another direction (rather than trying to measure how long light takes to travel a distance, use a light wave and that the speed of a wave = frequency * wavelength).

Part of the thing to remember as science evolves is that reality always wins. If it works, it's not going to suddenly not work because you learned there's another factor that wasn't considered. Pendulum clocks still work even after relativity was conceived of. GPS will still work even if we discover relativity's missing some fringe effects or something.

It's a founding principle of science in general that the rules stay the same over time, even if our understanding of the rules changes. We have no reason to think that gravity can or will suddenly reverse, so that mass repels other mass (and everything flies apart).

[Yora]

The weirdness of measuring the speed of light is, that it works even when the equipment used to measure it is moving. No point on earth is stationarry, as the earth rotates on its axis, revolves around the sun, the sun rotates around the center of the galaxy, and the galaxy is moving away from the center of the universe. But if I understood it correctly, you don't need to factor all these things into the measurement, it still always gets the same result.
Which on macro scale is not the case.