# Remember those superluminal neutrinos?



## Kopachris (May 31, 2010)

Faulty cable is to blame.

Just thought I'd let y'all know. Discuss.


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## Dodecaplex (Oct 14, 2011)

So the falsification has been falsified. The question is: when will the falsification of the falsification be falsified?


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## kv466 (May 18, 2011)

They still look beautiful when you're laying back and looking up at the sky.


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## Fsharpmajor (Dec 14, 2008)

I'm not a physicist, but that said, I thought there would turn out to be a measurement error. Why should neutrinos travel only a tiny fraction faster than the speed of light? Why not twice as fast, or ten times as fast, or whatever?


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## Ukko (Jun 4, 2010)

kv466 said:


> They still look beautiful when you're laying back and looking up at the sky.


My doctor has told me that those things were 'floaters'. I _knew_ they were neutrinos captured by my eyeball!


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## Philip (Mar 22, 2011)

Fsharpmajor said:


> I'm not a physicist, but that said, I thought there would turn out to be a measurement error. Why should neutrinos travel only a tiny fraction faster than the speed of light? Why not twice as fast, or ten times as fast, or whatever?


measurement error is taken into account.



Dodecaplex said:


> So the falsification has been falsified. The question is: when will the falsification of the falsification be falsified?


_'Faster-than-light' particles may have been even speedier_

in a newspaper near you!


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## Fsharpmajor (Dec 14, 2008)

I don't mean statistical margins of error, which would have been taken into account when reporting the results of the experiment in the first place, but rather, unanticipated sources of error. As I've said, I'm not a physicist, and any input from the physicists who frequent TC would be very welcome.


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## Ukko (Jun 4, 2010)

Fsharpmajor said:


> I don't mean statistical margins of error, which would have been taken into account when reporting the results of the experiment in the first place, but rather, unanticipated sources of error. As I've said, I'm not a physicist, and any input from the physicists who frequent TC would be very welcome.


I have been educated by watching The Big Bang Theory to the extent that I would expect a _simple technician_ to check the cables; physicists not so much.


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## mmsbls (Mar 6, 2011)

Hilltroll72 said:


> I have been educated by watching The Big Bang Theory to the extent that I would expect a _simple technician_ to check the cables; physicists not so much.


I have never seen The Big bang Theory. In real experiments technicians might make a cable or build a circuit card, but physicists do the calibration, testing of software and hardware, data taking, and constant checking of results. I would have expected that before publishing, the physicists on the Opera experiment would have checked, tested, calibrated every part of the detector repeatedly several different ways if possible. When you get a result that violates significant established physics _and_ disagrees with prior experimental results. you make certain you understand every part of your detector and know that they are working correctly.


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## Kopachris (May 31, 2010)

mmsbls said:


> Hilltroll72 said:
> 
> 
> > Fsharpmajor said:
> ...


You also have to keep in mind that the sheer scale of any experiment involving particle accelerators means there are *a lot* of cables. To check every connection before each experiment would take either weeks or hundreds of people, either way making the experiment too costly. Particle accelerators and detectors are delicate instruments. That means lots of delicate cables and delicate connections.


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## aleazk (Sep 30, 2011)

Kopachris said:


> You also have to keep in mind that the sheer scale of any experiment involving particle accelerators means there are *a lot* of cables. To check every connection before each experiment would take either weeks or hundreds of people, either way making the experiment too costly. Particle accelerators and detectors are delicate instruments. That means lots of delicate cables and delicate connections.


Kopa, @mmsbls _is_ an experimental particle physicist!.



> When you get a result that violates significant established physics *and disagrees with prior experimental results*. you make certain you understand every part of your detector and know that they are working correctly.


Exactly. I think this experiment will serve as a reminder of the fact that doing the things right is more important than a quick publication (of dubious quality). If at the end it results that in fact the superluminal thing was because of a (non properly checked) fault in the equipment, man, if I were part of that experimental team, after all the media scandal (which is in part fault of the team because of their premature publication, something that sadly it has become a rule in modern physics), I would be very embarrassed!. We are talking of Special Relativity, a key stone of modern physics, a crucial ingredient in Quantum Field Theory. A theory that has been checked several times before with astonishing accuracy. Those guys of the Opera team were very wrong in publishing their results so quickly, thing that, as I said before, it has become a rule, it seems. I know that there's a lot of pressure on the team, a lot of money has been inverted, but this is physics, and the _true_ is more important...


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## Kopachris (May 31, 2010)

aleazk said:


> Kopa, @mmsbls _is_ an experimental particle physicist!.


Oops. Well, the point still stands, and I disagree that they were wrong to publish their results. When they published, they made it very clear that their findings were extremely anomalous and some sort of equipment failure was likely to blame. They never made any claims about undoing special relativity--they merely reported what happened and asked others to check their work. Also, there's more.


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## waldvogel (Jul 10, 2011)

The faster-than-light neutrino story reminds me of the very early "discovery" of the first extra-solar planet, which was purportedly orbiting a nearby star called 61 Cygni. This star has a noticeable "proper motion" through the sky, meaning that it's close enough and moving at enough of an angle for astronomers to notice that it changes location with respect to more distant stars.

Astronomers at, I believe, Yerkes observatory, saw a periodic oscillation in this motion, showing that 61 Cygni was actually moving in a shape somewhat similar to a sine wave. They then announced that this oscillation was due to the presence of a hidden planet which was causing the visible star to move around the mutual centre of mass.

No other observatories found this wave-like motion to be true. And after many years, it was found that the observations of 61 Cygni took place after the periodic cleaning of the lens on the telescope. When the lens was returned to its mount, it was in a slightly different location. Because the lens was not perfectly symmetrical, it made the tracks of the stars over a period of time look non-linear...


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## mmsbls (Mar 6, 2011)

My comments on the Opera experiment may have been worded a bit too strictly. As Kopachris points out, these experiments are extraordinarily complicated, and there are many possibilities for error. In general the detector is calibrated frequently both to test the proper working of the detector and to ensure that all measurements are within the expected uncertainty. During data taking, there are usually real time programs that analyze the data and show a set of results that can be viewed to ensure things are working correctly. But complex issues can introduce systematic errors that are not found in a timely way.

I'm not familiar with how Opera calibrated their timing with the GPS. I have to believe that the system was studied carefully and that the physicists believed that they fully understand the calibration. If the cable was good at one time and later became defective, I think they should have noticed a clear change in timing so I assume that the cable was bad from the beginning. I'm not sure why a 60 nsec offset would not have been found during initial calibration, but perhaps there is not a good way to calibrate the entire timing system.

On my experiment we found a horrible error that did not effect results but caused us to lose certain data. Runs were typically 10 months or so long. About 2/3 of the way through one run we realized that our efficiency for detecting muon related events was lower than it should have been. The problem involved a complex issue with both hardware and software.

I agree that they should have released the paper if they truly believed their results. There is always tremendous tension between getting an important result out and making sure that everything is correct. One experiment led by a Nobel prize winner was going to release two papers/talks within a year announcing potentially huge discoveries. Both ended up being wrong. They ended up withdrawing one of them before the talk. Science is _very_ hard, and mistakes are made. That's why we scientists tend to be very skeptical _especially_ of new results that would change what we thought we knew.


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