CERN team claims measurement of neutrino speed >c

[ZapperZ]

The OPERA result has the most serious challenge to date, and it comes from a sister experiment located also in San Grasso.

http://arxiv.org/abs/1110.3763

The experiment uses the same neutrino source from CERN, and the neutrinos also traveled the same distance. They found the muons created from the neutral-current weak-interaction radiation from the neutrinos have an energy spectrum consistent to what one would expect if the neutrinos were moving at c, not at the speed found by OPERA.

Tommaso Dorigo has a detailed analysis of this work on his blog, if anyone follows or knows how to find that.

Zz.

 

[DevilsAvocado]

Thanks - that looks very convincing!

You’re welcome, but I think Zz deserves the 'credit'.

Yup, looks like a very big nail in the coffin:

http://www.science20.com/quantum_diaries_survivor/icarus_refutes_operas_superluminal_neutrinos-83684

ICARUS Refutes Opera's Superluminal Neutrinos
...
Given a neutrino moving at a speed v>c as the one measured by Opera, and given the distance traveled to the Gran Sasso cavern, one can relatively easily compute the energy spectrum of observable neutrinos at the cavern, given the production energy spectrum.
...
Neutrinos at CERN are produced with an average energy of 28.2 GeV, and neutrinos at the receiving end - the LNGS where Opera and ICARUS both sit - should have an average energy of only 12.1 GeV for neutrinos detected via charged-current interaction.
...

 

[pnmeadowcroft]

I have just completed a full listing of external links from this thread, using original authors and titles, available here https://www.physicsforums.com/blog.php?b=3453

In the process I noticed that the following basic links have not been posted yet:

Opera Useful Links http://www.nu.to.infn.it/exp/all/opera/#Useful Links

Opera Home Page http://operaweb.lngs.infn.it/

Cern Public Page http://public.web.cern.ch/public/

Long-Baseline news http://www.hep.anl.gov/ndk/longbnews/

 

[Aether]

http://physicsforme.wordpress.com/2011/10/19/neutrino-watch-speed-claim-baffles-cern-theoryfest/" article seems to confirm what I said before about the Cohen-Glashow/ICARUS hypothesis: "...neutrinos can’t travel faster than light unless electrons do too...".

But, why must super-luminal electrons necessarily "emit a cone of Cerenkov radiation in empty space"? How would momentum be conserved in such a process?

As I understand it, Cerenkov radiation can occur within a refractive medium, where the speed of light is less than c, only because the momentum of a photon does not decrease along with the reduction in the speed of light within the refractive medium.

Another strike against the speedy neutrinos comes from the fact that neutrinos are linked to certain other particles – electrons, muons and tau particles – via the weak nuclear force. Because of that link, neutrinos can’t travel faster than light unless electrons do too – although electrons needn’t travel as fast as the neutrinos.

Speedy electrons

CERN physicist Gian Giudice, who spoke at the seminar, and colleagues looked into what would happen if electrons traveled faster than light by one part in 100,000,000, a speed consistent with the OPERA neutrino measurement. Such speedy electrons should emit a cone of Cerenkov radiation in empty space – but previous experiments show that they don’t.

The only way out, theorists at the meeting decided, was to break another supposedly fundamental law of nature – the conservation of energy. But that suggestion seems even more ludicrous than breaking the speed of light.

 

[Aether]

What if you tried to "de-statistify" the experiment: can you in practice fire one sole proton at a time from CERN to Gran Sasso? If yes:

i) how often would you be able to do this per second; and
ii) assuming you can fire one proton per second, how long would you need to wait on average to have one neutrino detected at Gran Sasso?

IH

According to http://news.sciencemag.org/scienceinsider/2011/10/faster-than-light-result-to-be.html?ref=hp" article, new experiments will be conducted soon with a proton pulse width of 1 to 2ns, and an interval between pulses of 500ns. That will allow for about 2million pulses per second, and the OPERA collaboration expects to detect about twelve neutrinos from these pulses over a ten day period. That's one neutrino detection per 144billion pulses.

Ha ha, I bet there are many folks in the OPERA collaboration who would have liked to have been able to do this new experiment before going public with their first result, but maybe the publicity was necessary in order to get to this new experiment.

 

[gvk]

I'd like to ask what would be the OPERA's result if the proton bunch duration instead of 10 microsecond would have just 10 nsec?

So, they decided to proceed in this way, but with much less width:
"The new measurements will involve a change in the CERN neutrino beam. CERN makes the particles by colliding proton pulses with a graphite target, with each pulse being about 10,500 nanoseconds long. CERN has now split these pulses up so that each one consists of bunches lasting 1 to 2 nanoseconds; bunches are separated by gaps of 500 nanoseconds. "

I bet that now in OPERA, Lorentz, Einstein, Poincare, Minkowski and Co. withstand.

 

[Vanadium 50]

I have just done a massive cleanup of this thread.

I removed hundreds of messages that were either:

• Overly speculative
• Off-topic
• Repeats of points previously raised.
• Discussions of the "is not! is too!" variety.

 

[lalbatros]

So, they decided to proceed in this way, but with much less width:
"The new measurements will involve a change in the CERN neutrino beam. CERN makes the particles by colliding proton pulses with a graphite target, with each pulse being about 10,500 nanoseconds long. CERN has now split these pulses up so that each one consists of bunches lasting 1 to 2 nanoseconds; bunches are separated by gaps of 500 nanoseconds. "

I bet that now in OPERA, Lorentz, Einstein, Poincare, Minkowski and Co. withstand.

It could be that the high-resolution experiment wipes out the previous result.
There is however a serious chance that the result is confirmed, in which case an in-depth scrutinity of clock synchronization will be needed.

 

[Aether]

There is however a serious chance that the result is confirmed, in which case an in-depth scrutinity of clock synchronization will be needed.

The common view GPS method of clock synchronization isn't the same thing as slow clock transport, but we know that slow clock transport is fully equivalent to Einstein clock syncrhonization using two-way light pulses. So, when you can't send two-way light pulses directly between two points, such as between CERN and Gran Sasso, then you could accomplish the same synchronization using slow clock transport.

It would be interesting, and easy, to see if there was a difference between the clock syncrhonization that has been achieved using common view GPS, and what would be the result using slow clock transport. Does anyone have a link to a tutorial on the common view GPS clock synchronization method that compares its results with synchronization of clocks by slow clock transport?

I'm assuming that the "portable time transfer device" that OPERA used did not accomplish slow clock transport per se, but rather was a part of the implementation of common view GPS.

 

[DevilsAvocado]

http://physicsforme.wordpress.com/2011/10/19/neutrino-watch-speed-claim-baffles-cern-theoryfest/" article seems to confirm what I said before about the Cohen-Glashow/ICARUS hypothesis: "...neutrinos can’t travel faster than light unless electrons do too...".

I was just thinking... the quote you provided:

"neutrinos are linked to certain other particles – electrons, muons and tau particles – via the weak nuclear force"​

I have not understood everything yet in the excellent answers I got from Parlyne (in the fork https://www.physicsforums.com/showthread.php?t=541589"), this is the answer I got on right-handed neutrino interaction with the W and Z bosons (weak nuclear force):

"Purely right-handed neutrinos will not interact with the W and Z at all. The post-mixing heavy neutrinos of the Type I see-saw will interact with the W and Z; but, the interaction strengths will be tiny."​

[my bolding]

Then we have the Type II see-saw mechanisms, and I don’t know if the interaction strength is also tiny in this case...

However assume it is; how would this affect the link to the leptons? Is this why the state:

"although electrons needn’t travel as fast as the neutrinos"​

??

 

[Aether]

Then we have the Type II see-saw mechanisms, and I don’t know if the interaction strength is also tiny in this case...

However assume it is; how would this affect the link to the leptons? Is this why the state:

"although electrons needn’t travel as fast as the neutrinos"​

??

I don't think so, but I haven't looked at the thread "Neutrino Oscillations for Dummies" (yet). The energy spectrum that you posted is what seems (to me) to imply, in view of Cohen & Glashow's paper, that the maximum attainable velocity of electrons must be close to that of the muon neutrinos that were detected by ICARUS. The error bars on the ICARUS data, as far as I know, are what would still allow for the possibility that the maximum attainable velocity of electrons could be slightly different than the speed of neutrinos. Also, in general there is nothing to prevent any of the electrons from traveling slower than their maximum attainable velocity, so that could be what they meant by that (in the article that I quoted from) as well.

http://arxiv.org/abs/1109.5682" is what seems to be a relevant paper by the same physicist who was quoted in that article.

 

[Borek]

Moderation discussion moved here:

https://www.physicsforums.com/showthread.php?t=543873

 

[DevilsAvocado]

I don't think so ...

Okay, thanks Aether.

 

[deuticomet]

Likely, the explanation lies in the "don't-call-it-Sagnac-effect" effect. In any case, we will see if they go through all the peer-review process. Chances are that they don't get it published.

 

[deuticomet]

We need D = 18 meters ( 60 nanoseconds * c )

D = h / c * w * R * cos (theta) * cos (beta)

h = 20.000 km
c = 300.000 km / s
w * R = 465.1 m / s
cos (theta) = 0.7
cos (beta) = 0.82

Result, D = 17.8 meters

Pretty interesting that having the same order of magnitude than required, and an aproximate value (back-of-the-envelope calculation), close to the value, the hypothesis is completely ignored.

 

[phasta]

have they considered Newtons cradle? .. we all know of the desk based toy with 5 balls that clack back and forth.. well what if those balls were atoms and what if there were 600 miles of them in a row, a clack at one end would result in an instant movement at the other...and as the neutrino's are relatively sized to a regular atom as a golf ball is to our universe they are not individually registered, they are only counted as an electrical impulse, so its a false assumption that the one registered is the same one that was created. thoughts?

 

[DevilsAvocado]

No, no thoughts, just a recommendation to read the https://www.physicsforums.com/showthread.php?t=414380" before you post.

 

[DevilsAvocado]

... the hypothesis is completely ignored.

What makes you think that 160 researchers from 30 institutions and 11 countries working for 5 years would have missed something like this, if it has any value?

 

[PAllen]

have they considered Newtons cradle? .. we all know of the desk based toy with 5 balls that clack back and forth.. well what if those balls were atoms and what if there were 600 miles of them in a row, a clack at one end would result in an instant movement at the other...and as the neutrino's are relatively sized to a regular atom as a golf ball is to our universe they are not individually registered, they are only counted as an electrical impulse, so its a false assumption that the one registered is the same one that was created. thoughts?

Also, read the following FAQ:

https://www.physicsforums.com/showthread.php?t=536289

which shows one of the many fundamental misconceptions you have.

 

[kaonyx]

The UTC times CERN use are derived from GPS time by the receiver. The official spec alllows for +-100ns accuracy.
In practice the receiver companies claim a lot better, but it is interesting that they are not bound to a tighter standard.

 

[dan_b]

I'm not arguing that GPS clocks aren't used. I'm arguing that GPS clocks in an application requiring nanosecond-level synchronization of distant points is rare. Thus far, nobody has mentioned one.

Hi Vanadium,

I kind of lost track of the good stuff but now you sheared the sheep and I read it ALL. Er, I think I did! I didn't see a straight answer to your question so here's one: You know all those radio astronomers? Many of them use Very Long Baseline Interferometry, because they can. Nanosecond timing over long baselines? You bet. Academic? Sure, but there's a lot of them and they make good resolution radio-frequency pictures which proves their timing must be good, or else the pictures would be bad. They time lock the receivers local oscillators over huge distances so the individual receiver signals can be coherently combined. Tons of resolution that way. Not so much receiver net gain, of course, since they don't have enough money to pave over the whole world with antennas. :-) It's not all that rare.

 

[PatrickPowers]

What makes you think that 160 researchers from 30 institutions and 11 countries working for 5 years would have missed something like this, if it has any value?

Quite so. My Bayesian prior that neutrinos would move faster than light is close to zero. However my Bayesian prior that an error would be overlooked by this team is also close to zero.

So I don't worry about it, and will wait and see. Let people who are paid for it do the work.

 

[lalbatros]

A simple analysis gives no chance at all for the OPERA result to be relevant.
You can find it in this arXiv paper:

http://arxiv.org/PS_cache/arxiv/pdf/1110/1110.5275v1.pdf

Have a look at fig 4 from this paper:

[PLAIN]http://img543.imageshack.us/img543/3149/operadelays.jpg

Can you guess which of the red or blue curves isthe OPERA best fit?
If you can't make your choice, then this probably indicates the OPERA result is irrelevant.

 

[DevilsAvocado]

... Can you guess which of the red or blue curves is

Is this supposed to be a tricky question?

A blind coconut could see that the x-axis is ns, and which curve gets in/out first...

I think someone on BBC promised to eat his underwear live, if the OPERA result holds, I’m almost about to do the same on that the red curve is the OPERA result...

 

[lalbatros]

Is this supposed to be a tricky question?

A blind coconut could see that the x-axis is ns, and which curve gets in/out first...

I think someone on BBC promised to eat his underwear live, if the OPERA result holds, I’m almost about to do the same on that the red curve is the OPERA result...

I changed my question, but it is still easy to answer.
A blind coconut also knows that the OPERA team claimed a FTL result.
Maybe I should remove any comment.
The picture speaks for itself: CERN stumbled on a coconut.

Seriously, how is it possible to claim a six-sigma result on this basis?
Lies, damned lies, and statistics!

 

[DevilsAvocado]

CERN stumbled on a coconut.

 

[pnmeadowcroft]

You can find it in this arXiv paper:

http://arxiv.org/PS_cache/arxiv/pdf/1110/1110.5275v1.pdf

Nice paper H. Bergeron, he's good, really good. Presents the kind of analysis of the statistical that seemed appropriate for the original paper. He had to collect his data values from poor quality grafs, and still managed to demonstrate how the original 60ns result can be arrived at, as well as some of the weaknesses of the approach.

If the main paper does go to publish, I do hope it will come with full data, and the complete statistical calculations.

I've seen something else too, but I cannot quantify the effect yet. The height of the bars in Fig. 12 of the main paper effectively represents the chances of an event being misclassified into an earlier or later 50ns segment. However, due the the steep nature of the leading edge of the pulse, the probability of misclassifications resulting a higher number in a given 50ns segment is greater than the probability of misclassifications resulting in a lower number in a given segment. This would bias the curve fit at the leading edge towards a shorter flight time.

This can all be accounted for, but it is unclear from Fig. 12, again put the key data in the paper

 

[dgwsoft]

Faster-than-light neutrino experiment to be run again

With nanosecond proton pulses. As reported by the BBC

http://www.bbc.co.uk/news/science-environment-15471118

 

[danR]

This may be 'overly speculative', or already addressed, but assuming the result to stand, is the measured c in a real vacuum, the same as what it would be in an absolute vacuum devoid of zero-point fluctuating electromagnetic fields that would minutely reduce the propagation of light, analogously to the impedance of light through the electromagnetic fields always present in matter?

Neutrinos would not see any impedance, neither through matter nor in vacuo.

Even leaving aside zero-point fluctuations, empty space is not empty of electromagnetic noise, hence field fluctuations, from all manner of sources. If not a factor, I assume both sorts of things have been long accounted for in theoretical considerations of the value of c. Perhaps someone would know that.

 

[danR]

This is a systematic effect. You can take that to the bank.

They don't see a velocity dispersion. By itself, that's a huge problem. If you want to argue that not only are neutrinos faster than light, but they all travel at the same speed regardless of energy, you have to explain why the neutrinos from SN1987A arrived on the same day as the light did, instead of (as the Opera data would indicate) four years earlier.

Did anyone look for a signal four years earlier? Did a small, separate class of neutrino-component of the supernova emission behave differently from the rest of the pack?