Neutrinos go faster then light !

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chelle
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Re: Neutrinos go faster then light !

Post by chelle » Sun Sep 25, 2011 7:10 am

Harbles wrote:And here's another good item on this news.
http://scienceblogs.com/principles/2011 ... photon.php
Great article, thanks.

Here is an other interesting one:
http://www.guardian.co.uk/science/life- ... sfeed=true

... i found this comment at the end a bit strange:
I received a comment on this piece from Luca Stanco, a senior member of the Opera collaboration (who also worked on the ZEUS experiment with me several years ago). He points out that although he is a member of Opera, he did not sign the arXiv preprint because while he supported the seminar and release of results, he considers the analysis "preliminary" due at least in part to worries like those I describe, and that it has been presented as being more robust than he thinks it is. Four other senior members of Opera also removed their names from the author list for this result.
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Re: Neutrinos go faster then light !

Post by Xymox » Sun Sep 25, 2011 8:25 am

Well no doubt confirmation of the result by at least a second facility is required on this before its really confirmed..

There is that whole issue with the supernova.. Conclusively over a HUGE distance they seemed to obey the speed of light. The only seeming way to get both these results *might* be because of their widely differing energy. But this for me is a real sticking point.

I watched the conference twice. Man they seem to have covered every aspect very thoroughly tho and have a reasonably small margin of error..

Well there is no doubt at all. This faster then light stuff will only be valid if confirmed by a second facility. NO doubt about that.

Does anyone have any good articles on what the implications would be ? and speculation on what this result might mean yet ? How would a faster then light speed Neutrino effect physics ?

Im also wondering if this result might solve any currently unresolved issues ?

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Re: Neutrinos go faster then light !

Post by Physicist » Mon Sep 26, 2011 3:12 pm

Bartender: "Sorry we don't serve neutrinos in this pub!"
A Neutrino enters a bar

:D


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Re: Neutrinos go faster then light !

Post by Harbles » Mon Sep 26, 2011 5:48 pm

And the race to replicate is on. I thought it would be T2K but what with the earthquake and relatively short baseline it looks like it's up to Minos.

http://idealab.talkingpointsmemo.com/20 ... esults.php
and
http://www.popsci.com/technology/articl ... ight-claim

We shall see.


And a post suggesting that confusion about group or phase velocity is responsible.
http://scienceblogs.com/startswithabang ... s_with.php

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Re: Neutrinos go faster then light !

Post by chelle » Wed Sep 28, 2011 9:11 pm

Harbles wrote:And a post suggesting that confusion about group or phase velocity is responsible.
http://scienceblogs.com/startswithabang ... s_with.php
This one seems to be very convincing, also judging from the latest comments made on that blogpost, no?

Will there be a follow up conference where suggestions are discussed?

Image
I think I found what might be the problem; the systematic sampling bias that Ethan postulates is the problem. I get this from the thesis of Giulia Brunetti from the OPERA official site. Chapter 4.3, page 65 or so.
The scintillation fiber has a limited angle of acceptance. Photons can be generated anywhere in the plastic and can move in any direction. Those that move in certain angles are collected and transmitted by the wavelength lowering fiber. Those that move in different angles are lost. The time it takes for a photon to reach the PMT depends on the angle that it moves at. Those that move at lower angles take a longer path length to travel to the PMT and so have a longer delay. These photons are also more likely to be lost due to both absorption and also due to the angle of total internal reflection.
The delay in the fiber is calculated from laboratory measurements of the mean delay measured in a fiber. There is dispersion in the delay, the delay gets longer the longer the light is in the fiber. The light gets more attenuated the longer the delay.
What I think they are doing is curve fitting the output pulse to a model of what light inputs give that light output. That model uses both the light intensity recorded and also the timing of when the light was recorded, the dispersion of the transit time and also the mean delay time in the fiber as measured in the laboratory.
However, the system is set up to only record events where there are at least 10 triggers, that is where at least 10 PMTs have triggered, and then the fastest trigger (as calculated by the model) is taken as arrival time of that neutrino.
By only taking events where there are at least 10 triggers, the sampling is biased to only take events that have high light acceptance angles (and so are high magnitude events) and also events that had a low delay time (because they are high magnitude events). Using the mean delay as a fitting parameter when the distribution of events is biased by selection is (I think) not appropriate.
I think what this is doing is truncating the sampling of events that occurred later in the neutrino pulse (because their delays are too long), and events that occurred in certain parts of the apparatus (where they give long delays and attenuated signals).
There are two skewing events here. The skewing at the front end of the neutrino pulse only detects high magnitude (>10 trigger) events which are skewed to register as “faster”. The skewing at the back end is the rejection of the “slow” events that occur in the long time delay regions of the detector because they are low magnitude.
As Ethan points out, you don't need to move very many points by very much to change the “optimum” fit. If a few hundred or a few thousand data points were rejected because only 7, or 8, or 9 PMTs were triggered, and those happened to be “late” events, that could skew the whole distribution. Unfortunately the thesis says that only events with 10 triggers were recorded, so the 7, 8, 9 triggers might be lost. Looking at the relative timing of events vs the number of PMT triggers would be an important parameter. If there is bias, then it should show up in a skewed distribution.
If these neutrinos are moving faster than light, then their mass/energy which started out as subluminal protons somehow got accelerated to FTL so that the mass/energy that caused the interactions that was observed could arrive at the detector before light could. If real mass/energy can't be created or destroyed, then imaginary mass/energy or negative mass/energy can't be created or destroyed either. Where are the exotic particles with imaginary or negative mass/energy? None of them showed up in the detector and they looked pretty hard at what was detected. If they found some wild and exotic thing they would have reported it.
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Re: Neutrinos go faster then light !

Post by Harbles » Thu Sep 29, 2011 1:00 am

WARNING.
This video contains particle physicist humour.
http://www.youtube.com/watch?v=qJ0m13iJ ... ture=feedu
Sixty Symbols
Excellent as always.

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Re: Neutrinos go faster then light !

Post by Kasuha » Thu Sep 29, 2011 8:52 pm

Chelle wrote:Will there be a follow up conference where suggestions are discussed?
I doubt it, unless they find where did they do the error.

Regarding your suggested mechanism:
Shifting the whole pulse projection by the matching algorithm is my favorite, too. But I don't see your long quote any likely to be the cause. These optical cables are just about 2 m long and these differences come in picoseconds.
Besides the match shift I have two more hypotheses what might be wrong. Not much, they were very thorough. Time will tell.

Personally I'd suggest them to interleave their normal tau-neutrino search pulses with low percentage of LHC bunch fills (~10 ns bunches). That would not generate as many neutrinos, but by doing match against this pattern they can improve their match reliability by large margin. And they only need tens of neutrinos detected against background for that, not thousands.

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Re: Neutrinos go faster then light !

Post by Harbles » Sat Oct 01, 2011 1:49 am

Speaking of confirming OPERA's findings, I find this September 21, 2004 paper entitled;

"Proposal to Measure the Speed of Mu-type Neutrinos to Two Parts in 10^6"

Lay person question is two parts in ten to the sixth close to six sigma?
Anyhoo. Cost estimate under $320k capital and $30k per year operating costs.
Sounds like a deal.

http://minos-docdb.fnal.gov/0007/000765 ... mi0765.pdf

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Re: Neutrinos go faster then light !

Post by Kasuha » Sat Oct 01, 2011 7:12 am

As far as I know, Minos has measured similar difference in neutrino speed and got similar result to OPERA's, just with lower accuracy (about two sigma effect).

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Re: Neutrinos go faster then light !

Post by Harbles » Sat Oct 01, 2011 4:01 pm

I guess the point being if someone at Fermilab had come up with a measly $400k in 2005 it could have been OPERA confirming MINOS' results not the other way around.

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Re: Neutrinos go faster then light !

Post by Kasuha » Sat Oct 01, 2011 4:52 pm

Harbles wrote:I guess the point being if someone at Fermilab had come up with a measly $400k in 2005 it could have been OPERA confirming MINOS' results not the other way around.
Two sigma statistical certainity doesn't count as discovery in particle physics, six sigma does if confirmed. Nobody actually believed the Minos result is correct. Few people believe OPERA result is correct even now.

But it sure is true that the "threshold" of discovery is very uncertain nowadays. If LHC confirms Higgs at one of values that are found promising by Tevatron, who will be the discoverer?

I have heard OPERA originally measured much bigger difference, on level of 1 us. That's why they started the metrologic campaign which removed most of that except the last 60 ns. Should their error be to the other side they likely wouldn't care about it that much...

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Re: Neutrinos go faster then light !

Post by chelle » Sat Oct 01, 2011 8:43 pm

Kasuha wrote:But it sure is true that the "threshold" of discovery is very uncertain nowadays
In the good old days thresholds were like this:
“If it looks like a duck, swims like a duck, and quacks like a duck, then it probably is a duck.”

btw look at this one, and the bow-waves moving in front of it, why isn't it an option? Yes, extra dimensions and tachyons, but something simple isn't talked about, why?

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Re: Neutrinos go faster then light !

Post by adam_jeff » Mon Oct 03, 2011 8:15 am

Chelle:
Some kind of biased sampling could certainly account for the measurement.
But so far, no-one seems to have suggested a mechanism that would mean there are more neutrinos sampled from the front of the pulse than the end. I didn't really get why the thing with the fibers would cause that kind of skew, even if the magnitude were large enough: why would there be more 10-trigger events at the beginning of the pulse than the end?
Another thing to consider: most of the analysis so far has concentrated on the edges of the pulse (which are most important from the timing point of view). But the whole pulse is measured, and if there was a skew like you suggest there would be a slope on the measured profile compared to the one which is sent. There isn't, as shown in the graphs below.

Well done for managing to get in a mention of your theory via a duck. There's just one problem: the duck is moving slower than the speed of waves on water. If it was moving faster or the same speed, you would just see a shock wave at the front of the duck and no waves propagating in front of it. So a particle which is travelling at the speed of light would not have any waves in front of it.
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Re: Neutrinos go faster then light !

Post by chelle » Mon Oct 03, 2011 9:47 am

adam_jeff wrote:Well done for managing to get in a mention of your theory via a duck.
 
Thank you, her name is Neutrina : )
There's just one problem: the duck is moving slower than the speed of waves on water. If it was moving faster or the same speed, you would just see a shock wave at the front of the duck and no waves propagating in front of it. So a particle which is traveling at the speed of light would not have any waves in front of it.
I don't think so. 

The moment Neutrina starts to peddle forward, she will accelerates for a short while, and a bow wave is generated that is at first faster than her, and it expands for a limited distance away from her (see pic.). Once she is cruising at a constant speed, the bow waves travels along with her at that cruise control velocity. 

Now let's look at the Neutrino boys that are traveling from CERN to the Opera house, and you have very sensitive ears, than you'll 'hear' them arriving just before they 'really' arrive, due to the noise they make (bow waves). So them Neutrino's would always be detected a little bit before they actually arrive, as in 2 parts of a million, so to say?

For the speed of light, it is always measured by a photon hitting an electron directly, and generating electric current. So those measurements aren't done by focusing on the more soft sensitive weak force interactions.
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