# CERN team claims measurement of neutrino speed >c

It is. However, $(c - v)/c \equiv \epsilon \sim 10^{-5}$ is compatible with SR and the experimental uncertainty of all these experiments.

The energy of a particle travelling at this close speed to c is:
$$\begin{array}{l} \frac{E}{m \, c^2} = \gamma = \left ( 1 - \frac{v^2}{c^2} \right)^{-\frac{1}{2}} \\ = \left[ 1 - (1 - \epsilon)^2 \right]^{-\frac{1}{2}} \\ = \left[ 2 \epsilon \, \left( 1 - \frac{\epsilon}{2}\right) \right]^{-\frac{1}{2}} \\ \sim (2 \epsilon)^{-\frac{1}{2}} \, \left[1 + \frac{\epsilon}{4} + O(\epsilon^2) \right] \end{array}$$
Considering the rest energy of neutrinos is of the order of 0.1 eV, this means that the energy of these neutrinos would be of the order of:
$$\frac{0.1 \, \mathrm{eV}}{\sqrt{2 \times 10^{-5}}} \sim 20 eV$$
which is negligible. Even higher energies would bring the speed of neutrinos so close to c that the difference could not be detectable in any terrestrial experiment.

gvk
All right. Thank you, ICARUS.

ICARUS used a new measuring detector based on liquid argon time projection chambers, anybody knows why this way of measuring speed of neutrinos is better or more reliable than the one used by OPERA? or how this change in mesuring technique might affect the results?

PAllen
2019 Award
ICARUS used a new measuring detector based on liquid argon time projection chambers, anybody knows why this way of measuring speed of neutrinos is better or more reliable than the one used by OPERA? or how this change in mesuring technique might affect the results?
I assume the detector is irrelevant. Just a different group, re-doing the goedesy and timing independently; different time delays for cables etc.

Mistake of measurement (4 and 9) was very large according to dissagreement (0.3).
δt = (0.3 ± 4.0stat ± 9.0syst)ns
Does this mean that both mistakes (stat and syst) are really much smaller if they would be more precisely determined?

In a paper posted on the same website as the OPERA results, the ICARUS team says their findings "refute a superluminal (faster than light) interpretation of the OPERA result."

ICARUS did not detect any Cherenkov radiation.

"The result is compatible with the simultaneous arrival of all events with equal speed, the one of light." - ref. 2

Reference:
A search for the analogue to Cherenkov radiation by high energy neutrinos at superluminal speeds in ICARUS - ICARUS
Measurement of the neutrino velocity with the ICARUS detector at the CNGS beam. - ICARUS

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Staff Emeritus
2019 Award
It looks like it's that time again:

We think this will make the discussion go smoother.

V50, for the Mentors.

Let us assume that we measure speed and energy of neutrinos in the opposite direction that pions and kaons fly toward the target.
Is it so possible to reduce some velocities of neutrinos so much, that difference v-c would be measured?

p.s. According to Fig 1 in the mentioned article, pions and kaons fly toward the target.

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A few months were enough to cast serious doubts on the OPERA results.
The doubts originated from within the team itself.
The famous OPERA paper was of no use in this process.
One may then seriously question why this paper was published at all.
Was it too difficult to wait one more year?
After all, the main result will be that neutrinos propagates at the speed of light.

gvk
"One may then seriously question why this paper was published at all. Was it too difficult to wait one more year?"

Time is not a matter. It was the result of measurements during past 5 yrs, and as any team they should publish results regularly. The unusual thing they did not check equipments during this period of time. Any strange result should immediately draw their efforts to find faulty equipments. Their desire to make discovery was stronger.

As you said, gvk, they should have checked their equipment.
This is a question of taking what it needs to do these checks: mainly time.
There cannot be good arguments for deliberately publishing a wrong result.

It is really striking for me how much the OPERA team stressed the statistical errors of their measurement, when at the same time they completely neglected the systematic errors.
It has often been said that such a big team of experts could not make beginners mistakes.
Yet, this is exactly what they did:

- over-confidence in their equipment
- neglect of systematic errors
- blind confidence in an irrelevant statistical analysis​

There will probably be two things to be remembered from this story:

- neutrinos propagates at the speed of light
- do not trust anything, specially your equipment​

OnlyMe
Gold Member

In a paper posted on the same website as the OPERA results, the ICARUS team says their findings "refute a superluminal (faster than light) interpretation of the OPERA result."

ICARUS did not detect any Cherenkov radiation.

"The result is compatible with the simultaneous arrival of all events with equal speed, the one of light." - ref. 2

Reference:
A search for the analogue to Cherenkov radiation by high energy neutrinos at superluminal speeds in ICARUS - ICARUS
Measurement of the neutrino velocity with the ICARUS detector at the CNGS beam. - ICARUS
The issue involved here represents "null" results when looking for a proposed analogue Cherenkov radiation associated with FTL neutrinos. What I mean here is though the original paper by Glashow and Cohen has merit, it is a theoretical paper, with no confirmation. Until the theorized analogue Chenkov radiation has been experimentally confirmed any experiment that fails to detect it, represents a failure to detect it, not proof that it exists, does not exist or that neutrinos cannot exceed c.

The problem is, that to experimentally confirm the analogue radiation the FTL neutrinos must first be confirmed. FTL neutrinos remain questionable and likely will not be put to rest until later this year when additional experiments have been conducted at both CERN/OPERA/ICAUS(?) and MINOS. Even then a full examination may require more than a single season, unless the current systemic issue can be proven the origin of the original data and conclusions.

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So the head of the Opera team resigned and now they are saying that Neutrinos travel at the speed of light. Don't Neutrinos have mass? If so how can they travel at the speed of light?

http://www.bbc.co.uk/news/science-environment-17560379

Sandro Centro, co-spokesman for the Icarus collaboration, said that he was not surprised by the result.

"In fact I was a little sceptical since the beginning," he told BBC News at the time.

"Now we are 100% sure that the speed of light is the speed of neutrinos."

PAllen
2019 Award
So the head of the Opera team resigned and now they are saying that Neutrinos travel at the speed of light. Don't Neutrinos have mass? If so how can they travel at the speed of light?

http://www.bbc.co.uk/news/science-environment-17560379

Sandro Centro, co-spokesman for the Icarus collaboration, said that he was not surprised by the result.

"In fact I was a little sceptical since the beginning," he told BBC News at the time.

"Now we are 100% sure that the speed of light is the speed of neutrinos."
Please read at least some prior posts. This has been explained at least a dozen times in this thread. See, most recently, #751.

There will probably be two things to be remembered from this story:

- neutrinos propagates at the speed of light
- do not trust anything, specially your equipment​

Yea; and one more thing :
-- erroneous news always propogates faster than reality. :)

....

Nothing in the Universe moves faster than rumor.

Nothing in the Universe moves faster than rumor.
which is not breaking FTL because rumors on average contain no real information ;)

Hello falks! Can anybody inform me about last Opera experiment results? More specifically:
-How much energy was spent to run the neutrinos at C? Because according to relativity it needs infinite energy.And two relative questions:1.Can a particle be entirely converted to energy? 2.Does energy always have a carrier particle? Thanks a lot.

-How much energy was spent to run the neutrinos at C?
What do you mean? They can't go at c. Perhaps you mean extremely close to c? In which case one would use the relativistic formula for kinetic energy.

Can a particle be entirely converted to energy?
If it annihilates with its antiparticle, yes.

Does energy always have a carrier particle?
Do you mean that you're wondering if all energy manifests itself as the mass of a particle? I don't think so, due to Special Relativity, but I'm not exactly a reliable source for this sort of stuff, and the Higgs (if it turns out to be an existent particle) would complicate things.

The Gran Sasso experiments OPERA, ICARUS, LVD, BOREXINO presented preliminary results of the new neutrino speed measurements in May 2012- they are consistent with the speed of light within margin or errors:

Borexino: δt = 2.7 ± 1.2 (stat) ± 3(sys) ns
ICARUS: δt = 5.1 ± 1.1(stat) ± 5.5(sys) ns
LVD: δt = 2.9 ± 0.6(stat) ± 3(sys) ns
OPERA: δt = 1.6 ± 1.1(stat) [+ 6.1, -3.7](sys) ns

OPERA has also revised their 2011 results and will resubmit it to the "Journal of High Energy Physics":
δt = (6.5 ± 7.4 (stat.)+9.2 (sys.)) ns

Also MINOS from Fermilab corrected their former results
δt = −11.4 ± 11.2 (stat) ± 29 (syst) ns (68% C.L)

So Einstein is still laughing...

ZapperZ
Staff Emeritus
The press announcement from CERN on this result can be found here:

http://press.web.cern.ch/press/PressReleases/Releases2011/PR19.11E.html [Broken]

Zz.

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Yet more awards to put into the impressive trophy collection Einstein's theories hold...

The latest on Physorg:
http://phys.org/news/2012-06-einstein-neutrino.html

Scientists on Friday said that an experiment which challenged Einstein's theory on the speed of light had been flawed and that sub-atomic particles -- like everything else -- are indeed bound by the universe's speed limit.

Man, I forgot all about this! Hard to believe that it used to one of the big news stories that shook the science world in 2011.

Perhaps somebody should lock this thread up. No sense in beating a dead horse at this point.