Faster than the speed of light?

[cptn2016]

http://www.telegraph.co.uk/science/8782 ... light.html

Neutrinos at CERN have apparently been detected travelling faster than the speed of light...now I'm no physicist (quantum physics is endlessly fascinating but my IQ lags far behind my interest) but that seems like a pretty huge deal, if it is indeed confirmed.

[iflyforpie]

[tiggermoth]

Ahh heck, thats no big deal, "Spaceball 1" was able to go well past light speed years ago. They even have it on video

[tiggermoth]

oops, double post

[grimey]

probably not.

http://blogs.discovermagazine.com/badas ... more-38090

[mdscientist61]

Here is part of a lecture from when I was listening in a class in university many moons ago.

Visualize yourself standing on a seashore and the waves are coming in. The seashore is a straight-line beach (not a curved beach, not crescent-shaped). All the waves are coming in regular straight lines, evenly spaced, and all the waves are parallel.

The waves are coming in at an angle to the beach, such that the waves are breaking on the beach and the break is rolling from right to left as the wave comes in at an angle.

Obviously, the breaker that sweeps across from right to left is travelling faster than the wave.

Okay, now imagine that you are flying in your Boeing 474 and a radar wave is hitting the airplane from a radar station hundreds of miles away. The radar wave is similar to the waves coming in on the beach, except that the radar wave is travelling at the speed of light. Imagine that as you are flying along, the radar station is at a position 45 degrees to the right of your heading. So now, each wave of the radar signal will first strike the nose of your aircraft, then it will be like a breaking wave sweeping rearwards down the fuselage from the nose to the tail. So here the radar wave is travelling at the speed of light however the point where the radar wave touches the airplane (like the breaking wave) is travelling from the nose to the tail "faster than the speed of light".

The key point here is that although this wave touching point is travelling faster that the speed of light, it cannot carry any useful information. You cannot use it to send a signal from the nose to the tail to say "your door is open".

Who knows if at CERN they are seeing some kind of phenomenon similar to this except with neutrinos. (shrug??)

[North Shore]

Not a Shore original, but: "No surprises with this - everyone exceeds the speed limit in Italy!"

[grimey]

md, I know what you're referring to, and that's basically what has been the source of stories like this in the past, but I think this is different. They have a long distance separating the originating event and the detector, and they seem to be pretty clearly saying that the neutrinos from OPERA are getting to the distant detector 60ns before light could. I think if it were similar to the laser experiments there would be a fairly rapid clarification of exactly what it was that was supposedly happening.

http://news.sciencemag.org/sciencenow/2 ... tml?ref=hp

Jung, who is U.S. spokesperson for a similar experiment in Japan called T2K, says the tricky part is accurately measuring the time between when the neutrinos are born by slamming a burst of protons into a solid target and when they actually reach the detector. That timing relies on the global positioning system, and the GPS measurements can have uncertainties of tens of nanoseconds. "I would be very interested in how they got a 10-nanosecond uncertainty, because from the systematics of GPS and the electronics, I think that's a very hard number to get."

maybe the error bars aren't as large as they should be?

It's a very interesting result from an experiment WHICH HASN'T YET BEEN DUPLICATED. I'm not suggesting at all that the people responsible for the result are careless in the sense of Pons and Fleischmann, but there could be plenty of sources of error which they haven't accounted for. They're being fairly honest about it too, they got a bizarre result, did their best to eliminate any chance of it being a systematic error, and then felt a duty to publish the result:

However, even Ereditato says it's way too early to declare relativity wrong. "I would never say that," he says. Rather, OPERA researchers are simply presenting a curious result that they cannot explain and asking the community to scrutinize it. "We are forced to say something," he says. "We could not sweep it under the carpet because that would be dishonest." The results will be presented at a seminar tomorrow at CERN.

[niss]

[grimey]

http://www.bbc.co.uk/news/science-environment-15034852

http://en.wikipedia.org/wiki/Brian_Cox_(physicist)

[BigglesNBella]

Well, here's how physics works according to current theory:

Neutrinos have mass therefore they cannot travel faster than the speed of light because they would have to have infinite momentum and so it would take an infinite amount of energy to accelerate them to that speed.

Momentum formula that you may be used to: p = mv

Momentum formula at speeds approaching the speed of light (c) :

As you can see as v approaching c the denominator approaches zero and therefore momentum approaches infinity.

Thus, objects that have mass cannot reach or exceed the speed of light.

Would be pretty surprised to see this finding confirmed.

[ragbagflyer]

Well, here's how physics works according to current theory:

Neutrinos have mass therefore they cannot travel faster than the speed of light because they would have to have infinite momentum and so it would take an infinite amount of energy to accelerate them to that speed.

Momentum formula that you may be used to: p = mv

I'm no physicist but I guessing you can't use a newtonian type of momentum formula for subatomic particles.

Found this article today. It's pretty crazy what some people do for work!

http://www.wired.com/wiredscience/2011/ ... neutrinos/

[iflyforpie]

I'm no physicist but I guessing you can't use a newtonian type of momentum formula for subatomic particles.

In this case it isn't the size of the particles (which are generally governed by Quantum Mechanics) but the velocity. Any particle with mass will have that mass multiplied exponentially as it approaches the speed of light. As the formula BigglesNBella posted shows, that results in a zero denominator and we all know you can't divide by zero...

[ragbagflyer]

[
In this case it isn't the size of the particles (which are generally governed by Quantum Mechanics) but the velocity. Any particle with mass will have that mass multiplied exponentially as it approaches the speed of light. As the formula BigglesNBella posted shows, that results in a zero denominator and we all know you can't divide by zero...

But what I'm saying is can you even use the mass of a neutrino in that formula? My gut feeling is you can't, but I really have no idea.

[grimey]

he posted 2 formulas. The first was the traditional Newtonian formula for momentum, the second was the relativistic formula required by the special theory of relativity. Yes, you can use the mass of subatomic particles in it.

[iflyforpie]

Yes and any mass will make the formula go up exponentially as you approach the speed of light. No mass, no momentum, no energy required to accelerate it to the speed of light (Well, not quite. The problem of energy and light (photons) is why we came up with quantum mechanics in the first place).

[trampbike]

xkcd.com

[BigglesNBella]

Yes and any mass will make the formula go up exponentially as you approach the speed of light. No mass, no momentum, no energy required to accelerate it to the speed of light (Well, not quite. The problem of energy and light (photons) is why we came up with quantum mechanics in the first place).

I love how photons are "massless" particles and yet have momentum. That stuff blows my mind!

[BigglesNBella]

Potential Solution:

The relativistic motion of clocks on board GPS satellites exactly accounts for the superluminal effect, says physicist.

It's now been three weeks since the extraordinary news that neutrinos travelling between France and Italy had been clocked moving faster than light. The experiment, known as OPERA, found that the particles produced at CERN near Geneva arrived at the Gran Sasso Laboratory in Italy some 60 nanoseconds earlier than the speed of light allows.

The result has sent a ripple of excitement through the physics community. Since then, more than 80 papers have appeared on the arXiv attempting to debunk or explain the effect. It's fair to say, however, that the general feeling is that the OPERA team must have overlooked something.

Today, Ronald van Elburg at the University of Groningen in the Netherlands makes a convincing argument that he has found the error.

First, let's review the experiment, which is simple in concept: a measurement of distance and time.

The distance is straightforward. The location of neutrino production at CERN is fairly easy to measure using GPS. The position of the Gran Sasso Laboratory is harder to pin down because it sits under a kilometre-high mountain. Nevertheless, the OPERA team says it has nailed the distance of 730 km to within 20 cm or so.

The time of neutrino flight is harder to measure. The OPERA team says it can accurately gauge the instant when the neutrinos are created and the instant they are detected using clocks at each end.

But the tricky part is keeping the clocks at either end exactly synchronised. The team does this using GPS satellites, which each broadcast a highly accurate time signal from orbit some 20,000km overhead. That introduces a number of extra complications which the team has to take into account, such as the time of travel of the GPS signals to the ground.

But van Elburg says there is one effect that the OPERA team seems to have overlooked: the relativistic motion of the GPS clocks.

It's easy to think that the motion of the satellites is irrelevant. After all, the radio waves carrying the time signal must travel at the speed of light, regardless of the satellites' speed.

But there is an additional subtlety. Although the speed of light is does not depend on the the frame of reference, the time of flight does. In this case, there are two frames of reference: the experiment on the ground and the clocks in orbit. If these are moving relative to each other, then this needs to be factored in.

So what is the satellites' motion with respect to the OPERA experiment? These probes orbit from West to East in a plane inclined at 55 degrees to the equator. Significantly, that's roughly in line with the neutrino flight path. Their relative motion is then easy to calculate.

So from the point of view of a clock on board a GPS satellite, the positions of the neutrino source and detector are changing. "From the perspective of the clock, the detector is moving towards the source and consequently the distance travelled by the particles as observed from the clock is shorter," says van Elburg.

By this he means shorter than the distance measured in the reference frame on the ground.

The OPERA team overlooks this because it thinks of the clocks as on the ground not in orbit.

How big is this effect? Van Elburg calculates that it should cause the neutrinos to arrive 32 nanoseconds early. But this must be doubled because the same error occurs at each end of the experiment. So the total correction is 64 nanoseconds, almost exactly what the OPERA team observes.

That's impressive but it's not to say the problem is done and dusted. Peer review is an essential part of the scientific process and this argument must hold its own under scrutiny from the community at large and the OPERA team in particular.

If it stands up, this episode will be laden with irony. Far from breaking Einstein's theory of relatively, the faster-than-light measurement will turn out to be another confirmation of it.