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http://news.sciencemag.org/sciencenow/2011/09/neutrinos-travel-faster-than-lig.html?ref=hp wrote:
Neutrinos Travel Faster Than Light, According to One Experiment
by Adrian Cho on 22 September 2011, 2:28 PM | 0 Comments

Fat lady singing? The OPERA particle detector may have spotted neutrinos traveling faster than light, which would bring down the curtain on special relativity as an exact theory. Credit: OPERA collaboration

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<<If it's true, it will mark the biggest discovery in physics in the past half-century: Elusive, nearly massless subatomic particles called neutrinos appear to travel just faster than light, a team of physicists in Europe reports. If so, the observation would wreck Einstein's theory of special relativity, which demands that nothing can travel faster than light.

In fact, the result would be so revolutionary that it's sure to be met with skepticism all over the world. "I suspect that the bulk of the scientific community will not take this as a definitive result unless it can be reproduced by at least one and preferably several experiments," says V. Alan Kostelecky, a theorist at Indiana University, Bloomington. He adds, however, "I'd be delighted if it were true."

The data come from a 1300-metric-ton particle detector named Oscillation Project with Emulsion-tRacking Apparatus (OPERA). Lurking in Italy's subterranean Gran Sasso National Laboratory, OPERA detects neutrinos that are fired through the earth from the European particle physics laboratory, CERN, near Geneva, Switzerland. As the particles hardly interact at all with other matter, they stream right through the ground, with only a very few striking the material in the detector and making a noticeable shower of particles.

Over 3 years, OPERA researchers timed the roughly 16,000 neutrinos that started at CERN and registered a hit in the detector. They found that, on average, the neutrinos made the 730-kilometer, 2.43-millisecond trip roughly 60 nanoseconds faster than expected if they were traveling at light speed. "It's a straightforward time-of-flight measurement," says Antonio Ereditato, a physicist at the University of Bern and spokesperson for the 160-member OPERA collaboration. "We measure the distance and we measure the time, and we take the ratio to get the velocity, just as you learned to do in high school." Ereditato says the uncertainty in the measurement is 10 nanoseconds.

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.

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."

Jung, who is 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."

No previous measurements obviously rule out the result, says Kostelecky, who has spent 25 years developing a theory, called the standard model extension, that accounts for all possible types of violations of special relativity in the context of particle physics. "If you had told me that there was a claim of faster-than-light electrons, I would be a lot more skeptical," he says. The possibilities for neutrinos are less constrained by previous measurements, he says.

Still, Kostelecky repeats the old adage: Extraordinary claims require extraordinary evidence. Even Ereditato says that one measurement does not extraordinary evidence make.>>

The Alien wrote:http://www.bbc.co.uk/news/science-environment-15017484

.....But how?!

Chris Peterson wrote:They aren't saying their neutrinos went faster than c.

... That timing relies on the global positioning system, and the GPS measurements can have uncertainties of tens of nanoseconds. ...

OPERA neutrinos may travel at ~1.000025 c.

However, SN 1987A neutrinos traveled no faster than ~1.000000002 c

http://en.wikipedia.org/wiki/SN_1987A wrote:
<<SN 1987A was a supernova in the outskirts of the Tarantula Nebula in the Large Magellanic Cloud, a nearby dwarf galaxy. It occurred approximately 168,000 light-years (~1,470,000,000 light-years) from Earth close enough that it was visible to the naked eye

Approximately three hours before the visible light from SN 1987A reached the Earth, a burst of neutrinos was observed at three separate neutrino observatories. This may be attributable to the fact that neutrinos can travel faster than the speed of light (~1.000000002 c), but is also likely due to neutrino emission (which occurs simultaneously with core collapse) preceding the emission of visible light (which occurs only after the shock wave reaches the stellar surface). At 7:35 a.m. Universal time, Kamiokande II detected 11 neutrinos, IMB 8 neutrinos and Baksan 5 neutrinos, in a burst lasting less than 13 seconds.>>

SsDd wrote:
I have a question. Since we knew when the neutrinos were generated, (to the most possible accuracy at least), doesn't it really matter if the neutrinos were indeed faster than light, as long as no new information was communicated?

SsDd wrote:
Errrr, is having signatures a practice that is much frowned upon in Asterisk* ?

http://en.wikipedia.org/wiki/OPERA_experiment wrote:
<<The Oscillation Project with Emulsion-tRacking Apparatus (OPERA) is an experiment that was designed to perform a test of the phenomenon of neutrino oscillations. This experiment exploits the CNGS ("CERN Neutrinos to Gran Sasso"), a high-intensity and high-energy beam of muon neutrinos produced at the CERN Super Proton Synchrotron in Geneva pointing towards the LNGS underground laboratory at Gran Sasso, 730 km (450 mi) away in central Italy. OPERA is located in the Hall C of LNGS and it is aimed at detecting for the first time the appearance of tau neutrinos from the oscillation of muon neutrinos during their 3 millisecond travel from Geneva to Gran Sasso. In OPERA, taus resulting from the interaction of tau neutrinos will be observed in "bricks" of photographic emulsion films interleaved with lead plates. The apparatus contains about 150 thousand of such bricks for a total mass of 1300 tons and is complemented by electronic detectors (trackers and spectrometers) and ancillary infrastructure. Its construction was completed in the spring of 2008 and the experiment is currently collecting data. On May 31, 2010, OPERA Researchers announced the observation of a first tau neutrino candidate event in a muon neutrino beam. In September 2011, OPERA garnered international attention when it claimed detection of muon neutrinos traveling faster than light.

OPERA needs an intense and energetic beam of muon neutrinos traveling a distance of hundreds of kilometers to detect the appearance of oscillated tau neutrinos. A beam of this type is generated by collisions of accelerated protons with a graphite target after focusing the particles produced (pions and kaons in particular) in the desired direction. The products of their decays, muons and neutrinos, continue to travel in generally the same direction as the parent particle. Muon neutrinos produced in this way at CERN cross the earth crust reaching OPERA after a 732 km journey. This facility has been built at CERN between 2000 and 2005 and it started operation in summer 2006.

OPERA is located in the Hall C of the Gran Sasso underground labs. Construction started in 2003, and the apparatus was completed in summer 2008. In OPERA, the taus resulting from the interaction of tau neutrinos will be observed in "bricks" of photographic films ("nuclear emulsion") interleaved with lead sheets. Each brick has an approximate weight of 8.3 kg and the two OPERA targets contain about 150,000 bricks arranged into parallel walls and interleaved with plastic scintillator counters. Each target is followed by a magnetic spectrometer for momentum and charge identification of penetrating particles. During the data collection, a neutrino interaction is tagged in real time by the scintillators and the spectrometers, which also provide the location of the bricks where the neutrino interaction occurred. These bricks are extracted from the walls asynchronously with respect to the beam to allow for film development, scanning and for the topological and kinematic search of tau decays.

On 22 September 2011, the OPERA Collaboration garnered international attention, both public and within the physics community, when they released a claim that neutrinos had been observed traveling from CERN in Geneva to the OPERA detector at faster-than-light speed. The particles were measured arriving at the detector 60.7 nanoseconds prior to the time expected if they were traveling at light speed, with a margin of error of 10.1 nanoseconds (6.9 statistical, 7.4 systematic), a significance of 6-sigma. In particle physics, the standard baseline for a discovery announcement is 5-sigma significance. This result has not been detected by previous experiments; for instance, in 2007, Fermilab reported results consistent with neutrinos traveling strictly slower than light.>>

neufer wrote:
OPERA muon neutrinos may travel at ~1.000025 c.

However, SN 1987A electron neutrinos traveled no faster than ~1.000000002 c

http://en.wikipedia.org/wiki/SN_1987A wrote:
<<SN 1987A was a supernova in the outskirts of the Tarantula Nebula in the Large Magellanic Cloud, a nearby dwarf galaxy. It occurred approximately 168,000 light-years (~1,470,000,000 light-years) from Earth close enough that it was visible to the naked eye

Approximately three hours before the visible light from SN 1987A reached the Earth, a burst of electron neutrinos was observed at three separate neutrino observatories. This may be attributable to the fact that neutrinos can travel faster than the speed of light (~1.000000002 c), but is also likely due to neutrino emission (which occurs simultaneously with core collapse) preceding the emission of visible light (which occurs only after the shock wave reaches the stellar surface). At 7:35 a.m. Universal time, Kamiokande II detected 11 neutrinos, IMB 8 neutrinos and Baksan 5 neutrinos, in a burst lasting less than 13 seconds.>>

SsDd wrote:Just me contributing my spare CPU time to science. Errrr, is having signatures a practice that is much frowned upon in Asterisk* ?

a selection of papers discussing the recently discovered faster-than-light neutrino effect

New Constraints On Neutrino Velocities

Superluminal Neutrinos Without Revolution

On the Possibility of Superluminal Neutrino Propagation

The Hypothesis of Superluminal Neutrinos: comparing OPERA with other Data

Relativistic Superluminal Neutrinos

The OPERA Neutrino Velocity Result And The Synchronisation Of Clocks

A Possible Statistical Mechanism Of Anomalous Neutrino Velocity In OPERA Experiment?

A Comment On The OPERA Result And CPT

Superluminal Neutrinos And Extra Dimensions: Constraints From The Null Energy Condition

[i]Location of the Grand Sasso OPERA neutrino experiment in Italy - which receives a beam of neutrinos from CERN - and at faster than the speed of light, if you can believe it. (Credit: CERN)[/i]

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The recent news from the Oscillation Project with Emulsion-tRacking Apparatus (OPERA) neutrino experiment, that neutrinos have been clocked travelling faster than light, made the headlines over the last week – and rightly so. There are some very robust infrastructure and measurement devices involved that give the data a certain gravitas.

The researchers had appropriate cause to put their findings up for public scrutiny and peer review – and to their credit have produced a detailed paper on the subject, beyond just the media releases we have seen. Nonetheless, it has been reported that some senior members of the OPERA research team declined to be associated with this paper, considering that it was all a bit preliminary.

After all, the reported results indicate that the neutrinos crossed a distance of 730 kilometres in 60 nanoseconds less time than light would have taken. But given that light would have taken 2.4 million nanoseconds to cross the same distance anyway – there is a lot hanging on such a proportionally tiny difference.

It would have been a different story if the neutrinos had been clocked at 1.5% or 2% light speed, but this is more like 1.0025% light speed. And it would have been no surprise to anyone to have found the neutrinos travelling at 99.99% light speed, given their association with the Large Hadron Collider. So, confirming that they really are exceeding light speed, but only by a tiny amount, requires supreme confidence in the measuring systems used. And there are reasons to doubt that there are grounds for such confidence.

The distance component of the speed calculation had an error of less than 20 cm out of the 730 kilometres path, or 0.03% if you like, over the several years of data collection period. That’s not much error, but then the degree to which the neutrinos are claimed to have moved faster than light isn’t that much either.

But the travel time component of the speed calculation is the real question mark here. The release time of neutrinos from the source could only be inferred as arising from a 10.5 microsecond burst of protons from the CERN Super Proton Synchrotron (SPS) – fired at a graphite target, which then releases neutrinos towards OPERA.

[i]Some of the complex infrastructure required to infer the travel time of neutrinos across the OPERA experiment. (Credit Adam et al)[/i]

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The researchers substantially restrained the potential error (i.e. 10.5 microseconds) by comparing the time distributions of SPS proton release and neutrino detection at OPERA over repeated trials, to give a probability density function of the time of emission of the neutrinos. But this is really just a long-winded way of saying they could only estimate the likely travel time, more or less. And the dependence on GPS satellite links to time stamp the release and detection steps represents a further source of potential measurement error.

It’s also important to note that this was not a race. The 730 kilometre straight-line pathway to OPERA is through the Earth’s crust – which is virtually transparent to neutrinos, but opaque to light. The travel time of light is hence inferred from measuring the path distance. So it was never the case that the neutrinos were seen to beat a light beam across the path distance.

The real problem with the OPERA experiment is that the calculated bettering of light speed is a very tiny margin that has been measured over a relatively short path distance. If the experiment could be repeated by firing at a neutrino detector on the Moon say, that longer path distance would deliver more robust and more convincing data – since, if the OPERA effect is real, the neutrinos should very obviously reach the Moon quicker than a light beam could.

Until then, it all seems a bit premature to start throwing out the physics textbooks.

A contrary view – including reports that not all the Gran Sasso team are on board with the FTL neutrino idea.

• arXiv.org > hep-ex > arXiv:1109.4897 > 22 Sep 2011

• arXiv.org > hep-ph > arXiv:1110.0239 > 02 Oct 2011

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

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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.

• arXiv.org > physics > arXiv:1110.2685 > 12 Oct 2011