CERN team claims measurement of neutrino speed >c

[Dickfore]

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 traveling at this close speed to c is:
<br /> \begin{array}{l}<br /> \frac{E}{m \, c^2} = \gamma = \left ( 1 - \frac{v^2}{c^2} \right)^{-\frac{1}{2}} \\<br /> <br /> = \left[ 1 - (1 - \epsilon)^2 \right]^{-\frac{1}{2}} \\<br /> <br /> = \left[ 2 \epsilon \, \left( 1 - \frac{\epsilon}{2}\right) \right]^{-\frac{1}{2}} \\<br /> <br /> \sim (2 \epsilon)^{-\frac{1}{2}} \, \left[1 + \frac{\epsilon}{4} + O(\epsilon^2) \right]<br /> \end{array} <br />
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:
<br /> \frac{0.1 \, \mathrm{eV}}{\sqrt{2 \times 10^{-5}}} \sim 20 eV<br />
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.

 

[StevieTNZ]

This is in the news: http://www.physorg.com/news/2012-03-faster-than-light-particles-cross-check.html

 

[TrickyDicky]

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]

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.

 

[exponent137]

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?

 

[Orion1]

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
[/Color]
Reference:
A search for the analogue to Cherenkov radiation by high energy neutrinos at superluminal speeds in ICARUS - ICARUS
http://arxiv.org/ftp/arxiv/papers/1203/1203.3433.pdf

 

[Vanadium 50]

It looks like it's that time again:

Before posting in this thread, we'd like to ask readers to read three things:

• The PF Rules. Don't forget the section on overly speculative posts.
• The paper http://arxiv.org/abs/1109.4897
• he previous posts in this thread

We think this will make the discussion go smoother.

V50, for the Mentors.

 

[exponent137]

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.

 

[lalbatros]

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.
The headlines about FTL neutrinos will remain as a big mistake.

 

[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.

 

[lalbatros]

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]

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
[/Color]
Reference:
A search for the analogue to Cherenkov radiation by high energy neutrinos at superluminal speeds in ICARUS - ICARUS
http://arxiv.org/ftp/arxiv/papers/1203/1203.3433.pdf

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.

 

[Plebeian]

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]

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.

 

[Creator]

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. :)

...

 

[alexg]

Nothing in the Universe moves faster than rumor.

 

[Zarqon]

Nothing in the Universe moves faster than rumor.

which is not breaking FTL because rumors on average contain no real information ;)

 

[muhla]

Questions about Opera experiment results

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.

 

[Whovian]

-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.

 

[Histspec]

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:

http://francisthemulenews.wordpress...pera-en-2011-y-los-nuevos-resultados-de-2012/ (in Spanish)

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]

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

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

Zz.

 

[sshai45]

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

 

[StevieTNZ]

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.

 

[lmoh]

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.

 

[lalbatros]

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.

Most of the posts could be deleted, if not the whole thread.
After all, it was just an experimental difficulty, and most comments were irrelevant.

 

[TrickyDicky]

There's still something I find difficult to understand, the loose wire apparently can account for the 60ns advanced signal but looking at the original long experiment from 2009-2011 and specifically to figure 12 in the original paper, one knows that those 60ns were simply an average and that in fact neutrinos were detected in a range of δt from 1ns to over a hundred nanoseconds (at least that's what I gather, please correct if not the case). So I can't exactly see how a fixed sistematic error can give that dispersion in the detection times. Perhaps someone can shed some light about this.

 

[espen180]

I think the most likely explanation is that the signal delay due to the cable was not exactly 60 ns, but some distribution with mean 60 ns or higher and finite variance.

 

[TrickyDicky]

I think the most likely explanation is that the signal delay due to the cable was not exactly 60 ns, but some distribution with mean 60 ns or higher and finite variance.

Well, maybe so, still it would look to me a excesively "ad hoc" explanation but then I guess the only way to know for sure is repeating the experiment again in similar temporal circumstances to see if that distribution is eliminated.

 

[TrickyDicky]

In any case if the loose wire had such a behaviour I'm not sure it would correspond to a sistematic type of error.

 

[espen180]

No physical measurements have zero uncertainty. Any attempt to measure the delay of the wire will yield some distribution of delay times.

 

[Drakkith]

Well, maybe so, still it would look to me a excesively "ad hoc" explanation but then I guess the only way to know for sure is repeating the experiment again in similar temporal circumstances to see if that distribution is eliminated.

You want to repeat the experiment with a loose wire just to see if that particular fault was the cause of the errors? There's no reason to. They fixed it and the results immediately showed a change. In any case i doubt one could reproduce the exact amount of "looseness" in the wire the previous experiment had, so I don't know if it could even work.

 

[Histspec]

Well, maybe so, still it would look to me a excesively "ad hoc" explanation but then I guess the only way to know for sure is repeating the experiment again in similar temporal circumstances to see if that distribution is eliminated.

They are sure, because they compared the arrival times of cosmic muons in the LVD and OPERA detector (160m apart). They found, that between 2007-2008 and December 2011-2012 the data were in agreement, but between mid 2008 to December 2011, there was a 74ns discrpency, which vanished when the loose cable was fixed.
Second, they found another error due to an oscillator, contributing 15ns in the opposite direction.
Together, those effects caused the 59ns "anomaly". That's all.

In any case if the loose wire had such a behavior I'm not sure it would correspond to a systematic type of error.

Well, if the time of every single event is displaced by 59ns, then of course also the whole spectrum is changed in the same way. (OPERA will republish their results based on this error analysis).

Also note that in October-November 2011 (before the cable was fixed), OPERA used short bunched beams, which evaluation didn't require those statistics - also here the discrepancy was 60 ns.
But ICARUS measured the same bunched beam at the same time, and found no discrepancy. And in May 2012, another bunched beam run was performed, and OPERA, ICARUS, LVD, Borexino found no discrepancy too.

Opera: What went wrong
End of the Opera story

 

[TrickyDicky]

You want to repeat the experiment with a loose wire just to see if that particular fault was the cause of the errors? There's no reason to. They fixed it and the results immediately showed a change. In any case i doubt one could reproduce the exact amount of "looseness" in the wire the previous experiment had, so I don't know if it could even work.

No, you got it wrong, I meant with the wire tightened. Note I said I expected to have the odd distribution eliminated by doing that.

 

[TrickyDicky]

Well, if the time of every single event is displaced by 59ns, then of course also the whole spectrum is changed in the same way.

Wait, do you mean then
neutrinos actually had that broad variation in their speed but just shifted 59ns to have close to light speed average?

 

[Dickfore]

Wait, do you mean then
neutrinos actually had that broad variation in their speed but just shifted 59ns to have close to light speed average?

yes, see their table of systematic errors.

 

[TrickyDicky]

yes, see their table of systematic errors.

How can neutrinos have such different speeds? in such a short distance?

 

[Dickfore]

How can neutrinos have such different speeds?

Please don't spam old threads. What is your point of concern? nanosecond is not a unit of speed, so please clarify.

 

[TrickyDicky]

Note that the mentors have repeatedly told posters to read the original opera paper before posting here, anyone that has read it or has some notion about the relation of distance versus time (in ns or any other units) should see how the different δt (in ns) are related to neutrino speeds.

 

[ZapperZ]

Why is the original OPERA paper still being debated here? It is clear that the result from that paper no longer holds water.

Zz.

 

[TrickyDicky]

So far I've obtained two different explanations to my query, one that the loose wire error is purely sistematic and fixed (74ns) and the other that it actually it is responsible for the broad variation of \deltat in the first longer Opera experiment from 2008-2011.
Both answers are incompatible; as I said since the cable problem is considered a sistematic error I was thinking in terms of the first explanation, and with the reasonable assumption that neutrinos speed cannot oscillate so much in such a short distance (732km), I'm still missing something in the sense that the offered solution would work perfectly if the 60ns \deltat was not just an average. Of course my concern is only directed to the original experiment, not to the recent brief short pulsed ones. But I think it is important given the uproar it generated to have it all well clarified.

 

[TrickyDicky]

Why is the original OPERA paper still being debated here? It is clear that the result from that paper no longer holds water.

Zz.

Sorry, I thought this thread was specifically for discussion of that paper, if that is no longer the case I guess I'll just have to try elsewhere.

 

[ZapperZ]

Sorry, I thought this thread was specifically for discussion of that paper, if that is no longer the case I guess I'll just have to try elsewhere.

But the result of that paper has been clearly shown to be invalid! That's the whole point of the last few posts since that CERN press report! Or did you completely missed it?

It makes discussion of the original paper to be entirely moot!

Zz.

 

[TrickyDicky]

Note also that my questions were about that paper in the light of the new information released about the possible source of errors.

 

[TrickyDicky]

It makes discussion of the original paper to be entirely moot!

Even to get a better understanding of how exactly is the result invalidated according to the CERN press report? You give the term "discussion forum" a different sense from the one I'm used to. I thought one of the goals of such forums was asking questions in order to understand scientific issues thru the clarifications of other more learned forum members.

 

[ZapperZ]

Even to get a better understanding of how exactly is the result invalidated according to the CERN press report? You give the term "discussion forum" a different sense from the one I'm used to. I thought one of the goals of such forums was asking questions in order to understand scientific issues thru the clarifications of other more learned forum members.

Unless you are in possession of a detailed report on the exact timing errors that was done in the original OPERA result (i.e. you have the post-mortem analysis of those loose connection), what exactly do you have to base on in doing your "discussion"? The original OPERA paper certainly didn't have any. And the recent report on those loose connectors certainly have been lacking in the details on what exactly is the timing errors and how they were measured. So what exactly are you going to base your discussion on? SPECULATION? Guess work?

The same "philosophy" what was imposed upon in the beginning to urge people to read the original OPERA paper BEFORE they jump in into this discussion is also at work here. It means that the discussion must be based on something concrete, rather than something pluck out of thin air without any basis. Until the OPERA group publish clearly the post-mortem of the original result, you and I do not possesses any kind of data or information to make an informed discussion of what actually happened. So how would such a discussion gives you a "better understanding"? A better understanding on how to make guesses?

Zz.

 

[TrickyDicky]

Unless you are in possession of a detailed report on the exact timing errors that was done in the original OPERA result (i.e. you have the post-mortem analysis of those loose connection), what exactly do you have to base on in doing your "discussion"? The original OPERA paper certainly didn't have any. And the recent report on those loose connectors certainly have been lacking in the details on what exactly is the timing errors and how they were measured. So what exactly are you going to base your discussion on? SPECULATION? Guess work?

The same "philosophy" what was imposed upon in the beginning to urge people to read the original OPERA paper BEFORE they jump in into this discussion is also at work here. It means that the discussion must be based on something concrete, rather than something pluck out of thin air without any basis. Until the OPERA group publish clearly the post-mortem of the original result, you and I do not possesses any kind of data or information to make an informed discussion of what actually happened. So how would such a discussion gives you a "better understanding"? A better understanding on how to make guesses?

Zz.

OK, I understand you are an experimentalist , if you think there is no room for informed discussion from the data published so far I'll take your word. Let's not waste more time. However curiously from your words you seem to think (correct me otherwise) we all must agree that the original Opera experiment is dead and buried and no one should have any doubt about it unless he or she is an imbecile, and that without having all the data to supposedly have an informed discussion according to you as an experimentalist.

 

[Ilmrak]

So far I've obtained two different explanations to my query, one that the loose wire error is purely sistematic and fixed (74ns) and the other that it actually it is responsible for the broad variation of \deltat in the first longer Opera experiment from 2008-2011.
Both answers are incompatible; as I said since the cable problem is considered a sistematic error I was thinking in terms of the first explanation, and with the reasonable assumption that neutrinos speed cannot oscillate so much in such a short distance (732km), I'm still missing something in the sense that the offered solution would work perfectly if the 60ns \deltat was not just an average. Of course my concern is only directed to the original experiment, not to the recent brief short pulsed ones. But I think it is important given the uproar it generated to have it all well clarified.

I think your question has been misunderstood here. Let me try to interpret it, correct me if I'm wrong.

I read your question like “How could there be such a wide distribution in arrival times of neutrinos? Is it due to the loosing cable?”

If this was your question, then the answer is that the loosing cable caused (mainly) a systematic error which shifted the time distribution without deforming it significantly.
This mean that the variance of the time distribution is still there when you fix the cable. It is due mainly to three contributions (to my knowledge): a difference in neutrinos velocity, that is though negligible; a difference in the path followed (they are not created and received all in the same starting and ending points); other experimental errors.

I hope this could help.

Sorry for the bad English,

Ilm

 

[mfb]

The wide time distribution in the original publication has a simple explanation: The proton beams used to produce the neutrinos were long (~10µs if I remember correctly). Timing was not the main purpose of the experiment, just something which could be done in addition to the mixing measurements. After timing became interesting, they used short pulses (2ns?), as they are better to measure the flight time.

The 60ns were obtained by comparing the proton distribution (in time) with the neutrino distribution. Compared to the speed of light, a shift (but no broadening of relevant size) between the two was observed.