CERN team claims measurement of neutrino speed >c

  • #401
When you fire a bullet or a space rocket from the earth, they retain the angular momentum of the surface of the earth. Would this be true for a neutrino, or a photon? If true for a neutrino, with mass, but not for a photon, with no rest mass, then the neutrino would follow a curved path and the photon travel in a straight line. But in our rotating frame of reference it is actually the neutrino that would appear to travel in a straight line and the photon that would follow a curved path. To us the neutrino would be traveling a shorter distance than the photon. And so might arrive earlier. Any thoughts?
 
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  • #402
PAllen said:
I have to say I sympathize with lalbatros point of view on this. While it is interesting and useful to see what are the consequences of changing current theory in one respect (FTL neutrinos) while keeping core parts of existing theories, it seems quite an overstatement to call conclusions from that a refutation of an experiment. I greatly admire Glashow, and like that paper, but that one phrasing seems over the top to me. What we have in this paper is yet another reason to be skeptical of the OPERA claim, but hardly a refutation.
This was brave of you! :wink:
I couldn't agree more.
 
  • #403
Hum,

sorry to bring back this post.

I was just wondering, has there been any thought given about our whole universe
actually moving. I know it hard to imagine, since obviously we would have nothing to
compare this displacement with, but I can't really see why it couldn't be possible.

Could such a thing account for the difference in speed measured, and if it could what
would that speed need to be ?
 
  • #404
About "Measurement of the neutrino velocity with the OPERA detector in the CNGS beam"
( http://static.arxiv.org/pdf/1109.4897.pdf )
Somewhat late, but I had to think first..

In an experiment there is always a stimulus and a response.
Using a response for which there is no corresponding stimulus is invalid, because there was no experiment.
Using a stimulus for which there is no corresponding response is invalid as well, for the same reason.
The latter is the case in the current analysis of the OPERA Collaboration.

Only a part of the PEW contains start time information of the proton (stimulus) that later resulted in a neutrino detection (response).
The remaining parts or the PEW contain start time information of protons for which there was not a neutrino detection.
The current analysis allows the remaining parts to determine the shape of the PDF; it cannot be ruled out that this results in bias, because of the irrelevant start time information in the PEWs.

A number of physicists pointed out that these remaining parts are required for constructing the PDF to enable the maximum likelihood analysis and they dismissed the idea that this was invalid.
This seems the mainstream view and I am wondering what to think about that.
It explains why the analysis is taken for granted.

See also https://sites.google.com/site/bertmorrien/

Bert
 
  • #405
R32GTR said:
Hum, ... and if it could what would that speed need to be ?

Too fast to be measured and too slow to make any difference.
 
  • #406
If the shape of a light cone's leading surface is flat and all of its motion is thru space with no rest mass so no change in time and a neutrino shape as spherical with rest mass that dilates in time proportional to its shape make this discrepancy the difference between the photon and the neutrino and not their speed?
 
  • #407
There is a problem.
I want to know.
The speed of the protons to the target?
The rate of mesons to produce a neutrino?
 
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  • #408
Only a minority of the arXiv papers concentrate on the real topic: the experimental aspect.
The last one is also quite interresting:

http://arxiv.org/ftp/arxiv/papers/1111/1111.3284.pdf

Clearly also, the truth can be established only by those people who own the complete files.
 
  • #411
So FTL neutrinos confirmed after all, no error whatsoever.

So it seems measurement wasn't the issue after all.
I think its pretty obvious that there is a limit on speed, this is easily can be observed as particles gain mass as they approach light speed.

That leaves the possibility of us having a wrong measurement of light speed.

Also i know there are other threads about neutrinos but this is today's news that are confirming FTL neutrinos.
Link:
http://www.science20.com/quantum_diaries_survivor/opera_confirms_neutrinos_travel_faster_light-84763
 
  • #413
Nature report on the new experiment

http://blogs.nature.com/news/2011/11/neutrino_experiment_affirms_fa.html
 
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  • #415


This is just showing that the same experiment got the same result. Confirmation this is not. Confirmation will need to come from a different group.
 
  • #416


Pengwuino said:
This is just showing that the same experiment got the same result. Confirmation this is not. Confirmation will need to come from a different group.

But many different groups did the experiment and they all got the same results.

If there was an error don't you think the world scientific community would point it out?
I mean this took the scientists AND the public by surprise, so everyone is out to get the answer, don't you think if there was an 'error' people would found it already?

Obviously it has to do with very basic things, like the nature of neutrinos, or our understanding of light etc.
 
  • #417


Deicider said:
But many different groups did the experiment and they all got the same results.

What? OPERA is just 1 experiment

In fact, OPERA contradicts other experiments and observations.

If there was an error don't you think the world scientific community would point it out?
I mean this took the scientists AND the public by surprise, so everyone is out to get the answer, don't you think if there was an 'error' people would found it already?

They have been pointing out things on a daily basis. With complex experiments such as this, it's not a matter of someone saying "Oh you didn't do this" and the group saying "oh, duh, thank you, problem resolved". People on the outside don't have access to the experiment and can only rely on what OPERA has reported. Beyond that, just because people propose solutions doesn't mean that they are the solutions either.

You need a different experiment to confirm.
 
  • #418
This is the CERN statement:

OPERA experiment update 18 November 2011

Following the OPERA collaboration's presentation at CERN on 23 September, inviting scrutiny of their neutrino time-of-flight measurement from the broader particle physics community, the collaboration has rechecked many aspects of its analysis and taken into account valuable suggestions from a wide range of sources. One key test was to repeat the measurement with very short beam pulses from CERN. This allowed the extraction time of the protons that ultimately lead to the neutrino beam to be measured more precisely.

The beam sent from CERN consisted of pulses three nanoseconds long separated by up to 524 nanoseconds. Some 20 clean neutrino events were measured at the Gran Sasso Laboratory, and precisely associated with the pulse leaving CERN. This test confirms the accuracy of OPERA's timing measurement, ruling out one potential source of systematic error. The new measurements do not change the initial conclusion. Nevertheless, the observed anomaly in the neutrinos' time of flight from CERN to Gran Sasso still needs further scrutiny and independent measurement before it can be refuted or confirmed.

On 17 November, the collaboration submitted a paper on this measurement to the peer reviewed journal JHEP. http://arxiv.org/abs/1109.4897" .
 
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  • #420
Interestingly, the Nov. 17 version on arxiv gives no information about the new measurement in the PDF, and only one sentence in the non-pdf version of the abstract. Also, the JHEP journal reference isn't mentioned in the arxiv. I wonder if there will be further updates to the arxiv?
 
  • #421
PAllen said:
Interestingly, the Nov. 17 version on arxiv gives no information about the new measurement in the PDF, and only one sentence in the non-pdf version of the abstract. Also, the JHEP journal reference isn't mentioned in the arxiv. I wonder if there will be further updates to the arxiv?

They probably uploaded with the wrong pdf. The number of pages on arxiv is listed as 32 which doesn't match the pdf (24 pages). Should update it at some point.
 
  • #422
Jumpt to the bottom of this comment:

http://news.sciencemag.org/scienceinsider/2011/11/faster-than-light-neutrinos-opera.html?ref=ra

What is this story you can read there, about the 50 ns versus 10 ns window in the new experiment?
Where do the sciencemag get their information from?
Despite one hour looking on the net, I can't take the latest news as more than rumors without any supporting report.
Really a low in scientific method.
 
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  • #423
Another paper:

http://www.mashnews.com.au/world/neutrinos-still-faster-than-light-in-latest-version-of-experiment/

“With the new type of beam produced by Cern’s accelerators we’ve been able to to measure with accuracy the time of flight of neutrinos one by one,” said Dario Autiero of the French National Centre for Scientific Research (CNRS). “The 20 neutrinos we recorded provide comparable accuracy to the 15,000 on which our original measurement was based. In addition their analysis is simpler and less dependent on the measurement of the time structure of the proton pulses and its relation to the neutrinos production mechanism.”
 
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  • #424
  • #425
Er.. why do you have to upload anything? This is identical to the OPERA preprint uploaded on ArXiv. They have updated it (last update: Nov. 17- YESTERDAY!).

http://arxiv.org/abs/1109.4897

Edit: Please be aware that any research work coming out of CERN will be available for free under their Open Access policy:

http://library.web.cern.ch/library/OpenAccess/

Typically, they will be available on ArXiv. You should NOT go to any website that asks for password, personal info, or make you jump through various hoops for you to get them.

Zz.
 
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  • #426
ZapperZ said:
Er.. why do you have to upload anything? This is identical to the OPERA preprint uploaded on ArXiv. They have updated it (last update: Nov. 17- YESTERDAY!).

http://arxiv.org/abs/1109.4897

Edit: Please be aware that any research work coming out of CERN will be available for free under their Open Access policy:

http://library.web.cern.ch/library/OpenAccess/

Typically, they will be available on ArXiv. You should NOT go to any website that asks for password, personal info, or make you jump through various hoops for you to get them.

Zz.

When I opened the arxiv report two hours ago, there were only 24 pages.
Two hours lost for a 5 minute reading of section 9.
But the result is clear.
That's life.
 
  • #427
lalbatros said:
When I opened the arxiv report two hours ago, there were only 24 pages.
Two hours lost for a 5 minute reading of section 9.
But the result is clear.
That's life.

There are 32 pages now, and includes the short-bunch result.

Zz.
 
  • #428
These twenty neutrinos that were individually detected showed a fairly wide variation over their various measured times-of-flight. It would be interesting to see these individual time-of-flight measurements plotted against each respective particle's energy since the potential for an energy-dependent time-of-flight is a key open issue.

Maybe there is too much uncertainty in the time-of-flight measurements, and too few of them, to draw any conclusions from such a plot. Or, maybe nobody at OPERA has yet made such a plot. In any event, I think that they should either show such a plot in section 9 of their paper, or explain why they don't.
 
  • #429
here is the opinio of experimental Tommaso Dorigo (particle physicist working with the CMS experiment at CERN and the CDF experiment at Fermilab):

".. I will reiterate here the doubts I have on one of the time offsets necessary to obtain the timing measurement in Gran Sasso: an 8-km-long light guide brings in a 40,000+-1 ns offset: in order to determine a "delta t" of 60 nanoseconds, a subtraction of that large number has to be made. This offset was measured three years ago, and could have changed if the refraction index had changed even very slightly (e.g. due to aging of the plastic material). This offset was not remeasured in the new analysis, and the possible associated systematic uncertainty remains in my mind an issue.."
 
  • #431
  • #432
given the extraordinary difficulty of detecting neutrinos, and considering all the other variables inherent in such a complex measurement, how can they possibly believe they have now "confirmed" FTL neutrinos? publishing things like this all over major news websites seems to me to be the exact reason why far too many people feel justified in not trusting science.
 
  • #433
jnorman said:
... seems to me to be the exact reason why far too many people feel justified in not trusting science.

Okay, so you would trust science if every experiment performed that does not fit current theories is buried in the sand, and forgotten??
 
  • #434
jnorman said:
publishing things like this all over major news websites

Say this to people publishing these results. I doubt it is done by OPERA team.
 
  • #435
devilsadv - of course not, as that is the way science moves forward. but in the situation where such fundamental issues and the entire current foundation of SR, GR, and QM are at stake, it would behoove us to be extremely careful in what is reported publicly to news people who do not understand the complexities involved, nor the implications to physics.

you should spend a few minutes reading some of the comments posted on news websites in response to these articles - flabbergasting and frustrating to say the least.
 
  • #436
Borek said:
Say this to people publishing these results. I doubt it is done by OPERA team.

Exactly, blame the people who don’t understand plain English:
Dario Autiero @3:33

– We have chosen not to interpret our results in terms of new physics.


https://www.youtube.com/watch?v=AN9IQyHzk90​


Not the OPERA team.
 
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  • #437
jnorman said:
given the extraordinary difficulty of detecting neutrinos, and considering all the other variables inherent in such a complex measurement, how can they possibly believe they have now "confirmed" FTL neutrinos? publishing things like this all over major news websites seems to me to be the exact reason why far too many people feel justified in not trusting science.

They have said "The experiment shows FTL speed. Can someone please check the experiment because it's not supposed to be FTL?"

Two other labs have said "OK, challenge accepted."

The hype comes from bad journalism.

The part about not trusting science comes from listening to too much bad journalism (or creationists).
 
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  • #438
jnorman said:
... it would behoove us to be extremely careful in what is reported publicly to news people who do not understand the complexities involved, nor the implications to physics.

I understand, but what do you do? There will always be morons, making money on "sensational news"...

If 160 researchers from 30 institutions and 11 countries working for 5 years, get these results and can’t find that they did anything wrong, don’t you think it’s proper to report this to other scientist? To do further checks?

To me, this is a clear indication that science do work perfectly well. In a world of dogmatism, censorship and preconceptions this paper would have been 'banned' by the 'authorities'.

I think we should be grateful this didn’t happen...
 
  • #439
How long until the other labs' results are out?

Am I right in thinking it is both T2K and Fermilab? Is T2K operational after the natural disaster in Japan?
 
  • #440
DevilsAvocado said:
To me, this is a clear indication that science do work perfectly well.

I agree, at least we all have a job to scratch our heads for the next several months.

But I still on the skeptical side, because there are no a clear answer to why ICARUS and NOMAD contradict to the OPERA experiment and why FTL neutrinos do not radiate e^{+}-e^{-} pairs. There are, probably, another 2 dozens "why", and this is good!
 
  • #441
A question. Let’s say some scientist claims it turns out the speed limit of the universe is actually 8000 meters per second faster than the speed of light. What experiment would disprove that? The only thing I know of is the Michelson–Morley style interferometer. I’m not sure what effect a slightly faster speed limit would have on the interference pattern. Besides, it still wouldn’t measure a preferred inertial frame of reference. There’s no reason to assume a preferred frame just because the speed limit turns out to be faster than light. So I suspect it might have very small effect. So what would it take to disprove such a claim?
 
  • #442
DevilsAvocado said:
Dario Autiero @3:33

– We have chosen not to interpret our results in terms of new physics.
​

More verbosely, from page 29 of the revised OPERA preprint that has been linked to already:

In conclusion, despite the large significance of the measurement reported here and the robustness of the analysis, the potentially great impact of the result motivates the continuation of our studies in order to investigate possible still unknown systematic effects that could explain the observed anomaly. We deliberately do not attempt any theoretical or phenomenological interpretation of the results.

("Significance" in this context surely refers to "statistical significance" rather than to "impact" on fundamental physics.)
 
  • #443
One more thing from http://news.sciencemag.org/scienceinsider/2011/11/faster-than-light-neutrinos-opera.html?ref=ra:

" The collaboration has also checked its original statistical analysis, but today's decision to submit the results to a journal was not unanimous. "About four people" among the group of around 15 who did not sign the preprint have signed the journal submission, according to a source within the collaboration, while "four new people" have decided not to sign. That leaves the number of dissenters at about 15, compared with about 180 who did sign the journal submission.
"

And in absent of detailed description of OPERA experiment and measurement procedures, THIS IS better than nothing:
"A major concern among the dissenters is the fact that the "time window" within which neutrinos were detected by OPERA in the most recent run had a width of 50 nanoseconds, something that the leader of the superluminal analysis, Dario Autiero, only revealed once the tests had been carried out. It was initially assumed that this window was just 10 nanoseconds wide. This difference does not affect the final result itself, the source notes, but dissenters say it highlights poor experimental procedure. Some researchers are also unhappy that only a small fraction of the analysis, which was carried out by Autiero, has been independently checked by others within the collaboration. This leaves open the possibility, they say, that not all possible errors have been accounted for. "
 
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  • #444
I'm looking at the plot in fig. 18 of the Opera preprint, and it is quite intriguing that indeed there is a broad window of individual neutrino velocities of about 40-50 ns (from 40 to around 90) and all those individual σtimes don't overlap. I wonder if the plot reflects also the chronology of the neutrino arrivals from October 22nd to November 6th, I would guess so, and in that case it is weird that the neutrinos would seem to go faster everyday, that doesn't make much sense to me.
 
  • #445
TrickyDicky said:
I'm looking at the plot in fig. 18 of the Opera preprint, and it is quite intriguing that indeed there is a broad window of individual neutrino velocities of about 40-50 ns (from 40 to around 90) and all those individual σtimes don't overlap. I wonder if the plot reflects also the chronology of the neutrino arrivals from October 22nd to November 6th, I would guess so, and in that case it is weird that the neutrinos would seem to go faster everyday, that doesn't make much sense to me.

Or that there's an external source of error that is transient over time.
 
  • #446
Can some one explain why this cannot be the detection of the group velocity of the neutrino's rather than the actual particle it self. This would still prevent FTL communication and causality would be retained.

If the above is not possible it is slightly worrying as a science/physics teacher that I might actually have to learn some new physics but no one is sure what that physics is.

The thing about some of sceptisim about the results e.g. the electron -positron pairs chernakov radiation is based entirely on our current understanding of Physics. This current understanding is looking like it might have a big hole in it. Surely our existing theories do not correctly predict the implications of FTL particles as they suggest it really is a barrier. The idea of tachyons has never seemed real to me- particles created FTL and cannot slow down - many things in physics sound backwards but that is really backwards. It's a bit like using Newton's theory of gravitation to predict the implications of it own violations - it can't so a new theory was needed.

Maybe its time to sit back and wait for more results to confirm these findings and other experiments to test the speed of higher energy neutrino's to see if this effect get bigger.
Then maybe we will have to learn some new Physics. It's an exciting time for sure.
 
  • #447
FlexGunship said:
Or that there's an external source of error that is transient over time.

Yeah, that kind of feature would narrow the possible sources of error to look for.
 
  • #448
I seem to recall (and have searched this thread) that the neutrino's mass has some degree of uncertainty to it. Originally, it was believed to be massless but is now believed (known?) to have a very small mass.

Further, the limited reading I can find on the topic of how neutrino masses are determined seems to indicated that they are measured as the difference of the squares of the masses of the various neutrino flavors (meaning that the +/- sign could be lost??). Because of this, there's still a lot of uncertainty about the individual mass of a neutrino, right?

The abstract from a peer-reviewed paper from 2009 lists the mass of a neutrino as ~1.45eV based on gravitational lensing data (a fairly reliable direct measurement).
Neutrinos. – They can occupy in the cluster formation process all g = 12 left- and right-handed states, which gives m = 1.455eV.
(Source: http://iopscience.iop.org/0295-5075/86/5/59001/pdf/0295-5075_86_5_59001.pdf page-3)

A 2010 finding further refined the value of the combined masses of all three types of neutrinos to be 0.28eV.
As a result, MegaZ can only estimate the sum of the three neutrino masses. The galactic distribution suggests that the combined mass the three neutrino varieties is less than 0.28 electron volts.
(Source: http://www.sciencedaily.com/releases/2010/07/100712115104.htm)

So, all that's firmly known is that any particular flavor neutrino has a non-zero mass, that one flavor in particular has a mass of 1.455eV, and that the sum of all three neutrino masses is less than 0.28eV.

Is it possible that one (or two) of the three flavors of neutrino has negative mass or have I grossly misunderstood our current knowledge about neutrinos?

EDIT: Propagation time is a weighted average of the various velocities that the neutrino travels as it shifts flavors, so over very long distances, travel is slightly less than the speed of light (corresponding to the positive-mass sum of neutrino flavors). However, during very short trips, perhaps the likelihood that a neutrino occupies a negative-mass state is increased.
 
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  • #449
FlexGunship said:
I seem to recall (and have searched this thread) that the neutrino's mass has some degree of uncertainty to it. Originally, it was believed to be massless but is now believed (known?) to have a very small mass.
...
Is it possible that one (or two) of the three flavors of neutrino has negative mass or have I grossly misunderstood our current knowledge about neutrinos?

I think you can find some answers in this (fork) thread:

Neutrino Oscillations for Dummies
https://www.physicsforums.com/showthread.php?t=541589

And if expert Parlyne is still around, you could probably get additional help.


P.S. "Dummies" is referring to *me* nothing else... :smile:
 
  • #450
jtbell said:
More verbosely, from page 29 of the revised OPERA preprint that has been linked to already:

Thanks jtbell.
 

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