Roll over Einstein: Pillar of physics challenged

reply to post by davidchin


At the end of the day, the speed of light is just a constant for mathematical equations to work properly. If proved otherwise, the foundations of physics would need to revised entirely - and that move could be opposed by certain lobby groups with an agenda.

Neutrinos supposedly do have mass, so I've no idea how they reached c (let alone went past it).

Well , this certainly is interesting! I heard someone ask how something moving faster than light can be speed clocked.
I would imagine that rather than monitoring the object over its entire travel, two fixed points are established along its path of travel, and, knowing the distance between those two, a measurement is taken when it leaves point (a) and stopped when the object reaches point (b). Remember, the devices used to measure speed need not be able to follow every moment of the movement they are recording, just two points along the path.

Oh , and someone asked about the 'speed' of magnetism. As far as I know, magnetism is measured in strength , not speed. Thats probably why you have had trouble locating a reference for it.

In other news:

Someone just prove that the law of preservation of energy and the first law of thermodynamics are both wrong.
/joke

But in all seriousness, if this is really the case i would NOT be surprised anymore...faster than light? How much more significant and law altering can it get? I don't buy it at this time tho.

it would REALLY render MOST/ALL what we know from current physics "wrong" incl. our idea of space/time, Einsteins special relativity etc. The ramifications what such a finding would have would be mind blowing.

Originally posted by davidchin
I was under the impression that the speed of light was a "limit", not a "barrier". Which means that no physical entity could reach the speed of light. I recall working some equations back in college on contracting dimensions and increases in mass for objects travelling close to the speed of light, and upon examining the equations that we were given (probably simplified for us "unsophisticated" undergraduates), it seemed to me that teh equations also worked for objects that travelled at speeds faster than the speed of light. For such faster-than-light objects, they could never slow down to approach light speed due to the same dimensional and mass restrictions, and were forever destined to go much faster that light but somehow never able to slow down.

Are there any physics majors who might be able to address this?

That's pretty much what I was asking.
Thanks for making me feel a little bit valid

reply to post by EnochRoot


And you're both right.
There's really not much more to it than that... faster-than-light travel in Relativity is just the mirror image of slower-than-light travel. Objects moving slower than light can't go faster. Objects moving faster than light can't go slower.

In fact, davidchin, your description was pretty thorough. There's not much of interest beyond that undergrad explanation.

reply to post by DragonFire1024

The big question is whether OPERA researchers have discovered particles going faster than light, or whether they have been misled by an unidentified "systematic error" in their experiment that's making the time look artificially short. Chang Kee Jung, a neutrino physicist at Stony Brook University in New York, says he'd wager that the result is the product of a systematic error. "I wouldn't bet my wife and kids because they'd get mad," he says. "But I'd bet my house."

Source: Neutrinos Travel Faster Than Light, According to One Experiment

Yeah but a faster-than-light object had to break the light speed limit at some point, didn't it? Or did it just 'pop' into existence at that speed?

I understood time stands still at light speed. Time is a dimension. So in what dimension are these faster-than-light objects moving in?

Originally posted by CLPrime
reply to post by DragonFire1024

 

The big question is whether OPERA researchers have discovered particles going faster than light, or whether they have been misled by an unidentified "systematic error" in their experiment that's making the time look artificially short. Chang Kee Jung, a neutrino physicist at Stony Brook University in New York, says he'd wager that the result is the product of a systematic error. "I wouldn't bet my wife and kids because they'd get mad," he says. "But I'd bet my house."

Source: Neutrinos Travel Faster Than Light, According to One Experiment

We will soon See. Scientists in Chicago might to try and recreate the event: CERN Claims Faster-Than-Light Particle Measured - A similar neutrino experiment at Fermilab near Chicago would be capable of running the tests, said Stavros Katsanevas, the deputy director of France's National Institute for Nuclear and Particle Physics Research.

Katsanevas, who participated in the CERN experiment, said help could also come from the T2K experiment in Japan, though that is currently on hold after the country's devastating earthquake and tsunami in March.

Originally posted by FOXMULDER147
Yeah but a faster-than-light object had to break the light speed limit at some point, didn't it? Or did it just 'pop' into existence at that speed?

You answered your own question. Just as photons didn't accelerate to the speed of light, they just exist at that speed, faster-than-light particles wouldn't accelerate to more than the speed of light, they, too, would exist at that speed. If they exist at all.

I understood time stands still at light speed. Time is a dimension. So in what dimension are these faster-than-light objects moving in?

The simplified case states that they exist in the same time dimension...they just move through it in the opposite direction.

reply to post by DragonFire1024


But, then, if the same experiment is run in another location, should we not expect that the same systematic error could be present?

So does relativity exclude the possibility of faster than light objects? Or only that you cannot break the barrier (either way)?

reply to post by FOXMULDER147


Even though the equations hint at FTL travel, they are normally "ignored" by scientists because its not perceived to be "real".

Well I remember reading that back in 1998. They are called TACHYONS. (well apparently neutrinos and tachyons are not the same thing) They go faster than light... but they are still limited by the speed of light... they can't go SLOWER than the speed of light.

What I read in 1998... I don't remember if the tachyons were theorized... or they were newly discovered...

But since the LHC just ``found them`` apparently it was just a theory when I read about it. But from what I remember, in the article, they had observed them... anyways.

reply to post by FOXMULDER147


Only that you can not break the barrier either way.

To be specific, the very nature of objects is different at superluminal velocities. To travel faster than light, an object must have imaginary mass (that is, its mass must be a multiple of the square-root of -1). Also, the less energy that object has, the faster it moves.
And, I mentioned that the reversal of time is the simplified case. In fact, what occurs at superluminal velocities is that momentum becomes a space-like quantity, and time runs perpendicular to the way we experience it (that is, it exists on the imaginary plane), rather than actually running backwards.

However, superluminal velocities are allowed for neutrinos in a certain variation of the Standard Model (specifically, the Standard Model Extension), in which violations of invariance can occur. So, this is not something that is completely without theoretical precedent.

reply to post by DragonFire1024


In one of the threads on this that got closed, someone posted this link from NewScientist.

www.newscientist.com...

"Scientists have sent light signals at faster-than-light speeds over the distances of a few metres for the last two decades - but only with the aid of complicated, expensive equipment. Now physicists at Middle Tennessee State University have broken that speed limit over distances of nearly 120 metres, using off-the-shelf equipment costing just $500."

I'm not a scientist at all, but I try and keep up with what's happening in physics and cosmology, and I've never heard of experiments where light was made to exceed the speed of light.

I'd really appreciate it if someone here who understands physics could try and explain that in layman's terms.

reply to post by CLPrime


Do you believe then, that theres a chance that whatever this phenomenon turns out to be, that the particle was not accelerating , or decelerating to the speed of light, but must have come into existance at the speed at which it was recorded?

Pretty weird stuff this!

reply to post by Nonvexatious


Whenever you hear of some scientists causing light to travel either slower or faster than the speed of light, it's always speaking of phase velocity. Phase velocity and group velocity are two different things. In the case of light, it's the group velocity (the speed at which information is actually transmitted) which always travels at exactly 299,792,458 m/s. The phase velocity can travel at most any speed, from superluminal, as you quoted, to nearly stopped.

Originally posted by FOXMULDER147
So does relativity exclude the possibility of faster than light objects? Or only that you cannot break the barrier (either way)?

This is really something that Relativity was never intended to address. To our understanding, we only interact with sub-luminious and luminous particles/waves/whatever. The superluminous prospect is not excluded - but not really entertained by relativity.

One could suppose that the equations of relativity can still be used to describe hypothetical superluminous objects. But we have no known examples to really compare that to. It's like speculating on how particles with a "negative mass" would behave.... we have no known examples of that - and any theories are going to postulate the mechanics in a number of different ways with no real way of knowing until a particle with negative mass is discovered.

I suppose - in theory, particles with negative mass could move faster than the speed of light.... the stipulation, of course, being that those particles would, normally, flee from particles possessing mass (and, thus, making any kind of use of them would require an energy expense).

It's really hard to say. It's all imagichanics, at this point.

reply to post by TrueBrit


In the case of this experiment...I believe it's a systematic error.