Author Topic: Neutrino experiment repeat at Cern finds same result.  (Read 8259 times)

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Offline firewalker

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Neutrino experiment repeat at Cern finds same result.
« on: November 18, 2011, 07:07:36 pm »
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Offline SoftwareSamurai

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Re: Neutrino experiment repeat at Cern finds same result.
« Reply #1 on: November 18, 2011, 11:38:53 pm »
Yeah, I'm still not convinced there are FTL neutrinos. Supernova analysis haven't shown a FTL shift in neutrino speed. So I'm going to firmly stand next to Albert until more solid proof comes in.

Let's see them move their detection lab twice as far away and repeat the experiment again.
 

Offline don.r

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Re: Neutrino experiment repeat at Cern finds same result.
« Reply #2 on: November 18, 2011, 11:48:27 pm »
All you can do is modify the tests to answer the critics. I agree that they should change some of the variables like detector location. Ideally this will be confirmed by an independent team at another lab.
 

Offline amspire

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Re: Neutrino experiment repeat at Cern finds same result.
« Reply #3 on: November 19, 2011, 02:27:42 am »
If you assume that the neutrino's did travel at the speed of light, an equally valid news story could be:

"The GPS sync'ed time clock at the Gran Sasso National Laboratory is 60ns slow !"

It just doesn't sound as interesting. To get this accuracy from GPS, so they had to use a lot of compensating for errors.

They did verify the clocks with a portable atomic clock which should be good enough, but it is still not hard to make a mistake somewhere.
« Last Edit: November 19, 2011, 02:51:35 am by amspire »
 

Offline djsb

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Re: Neutrino experiment repeat at Cern finds same result.
« Reply #4 on: November 19, 2011, 09:42:38 am »
I heard on UK's channel 4 news last night (from a UK scientist) that there will be 2 independent tests carried out,one in  Japan and another one I can't remember.

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Offline ejeffrey

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Re: Neutrino experiment repeat at Cern finds same result.
« Reply #5 on: November 19, 2011, 10:12:01 am »
The MINOS project associated with Fermilab in the US claims they can characterize their delays and distance better and re-analyze the data they already have to get sufficient resolution to see the same effect.

This particular announcement is that they have completed one of the measurements a lot of other scientists asked about.  Basically, their previous system generated square-wave pulses of neutrinos with 10 microsecond pulses.  This made it impossible to assess the time-of-flight of a single neutrino, and only neutrinos at the leading and falling edges actually were useful.  Essentially 99% of their neutrinos were 'wasted', at least for the purpose of measuring time-of-flight.  They put the data into a giant statistical grinder that compared the detection events to the pulse waveform, and got an answer out.  Physicists are inherently distrustful of this sort of thing, even though it can be a quite legitimate data analysis technique.  Therefore, they modified their experiment to generate pulses of only 3 nanoseconds, spaced by a few hundred nanoseconds.  This means they can identify the time-of-flight of a single neutrino, so even with only 20 new events they can confirm their results.

So this result confirms that they were doing their statistical analysis correctly.  I am definitely looking forward to seeing some results from other groups here. I have seen a few manuscripts claiming to 'solve' the mystery, but none of them has really stood up to scrutiny.
 

Offline firewalker

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Re: Neutrino experiment repeat at Cern finds same result.
« Reply #6 on: November 19, 2011, 03:49:35 pm »
Notice, that no one says that netrinos travel faster than light. Netrinos seems to travel from point A to point B faster that light would. There is no law to prohibit that.

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alm

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Re: Neutrino experiment repeat at Cern finds same result.
« Reply #7 on: November 19, 2011, 04:52:09 pm »
How's that any different?
 

Offline SoftwareSamurai

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Re: Neutrino experiment repeat at Cern finds same result.
« Reply #8 on: November 20, 2011, 02:43:58 am »
Phil Plait is also skeptical. That's why I mentioned the supernova analysis that he brought up in his article. If neutrinos are indeed traveling FTL, and by such a large margin as 1 part in 40,000, then why haven't we "seen" them arrive at Earth so far in advance of the light photons of a pending supernova? Until this can be explained, I'm reserving my own skepticism about these test results.

My hunch is that either they've slipped a magnitude somewhere in their formulas/calculations (which just recently happened one group searching for the Higgs particle), or they're detecting other neutrinos not actually generated by CERN. Simply changing the pulse width/rate of the neutrino beam and verifying their clocks just isn't enough to rule out all experimental setup mistakes.
 

Offline amspire

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Re: Neutrino experiment repeat at Cern finds same result.
« Reply #9 on: November 20, 2011, 03:53:59 am »
How's that any different?

If neutrino's could arrive sooner without exceeding the speed of light, that would be a very interesting finding. It would mean that they can take a shorter path between A and B then light can. The concepts of the shortest path at a quantum level is very different to our concepts of a straight line at a macro level, and also there are all those other dimensions that physicists have been seriously proposing through string theory.

SoftwareSamurai has raised a critical point though. Why would there be a significant delay over this short distance, when it is not evident from supernovae?

Has some technician accidentally plugged a 10 meter coax cable somewhere where there is only means to be a 1 meter cable? That is all it would take to get this error.

Richard
 

Offline rf-loop

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Re: Neutrino experiment repeat at Cern finds same result.
« Reply #10 on: November 20, 2011, 09:25:56 am »


Has some technician accidentally plugged a 10 meter coax cable somewhere where there is only means to be a 1 meter cable? That is all it would take to get this error.

Richard

Just for fun. :)

60ns.
Normal coaxial cable velocity factor is arouund between 0.6 - 0.9 (dependent of many things in cable materials and dimensipons)

One common hobby lab grade cable is RG223
Its velocity factor is typically around 0.66. (insulation material PE) (this is not accurate and also nearly all things change it, cable humidity, mechanical stress, small differencies in material. Example insulating materials may have small differencies etc etc.

It can think that 20cm is 1ns
With cable it is very nice to make delays. Common way with old analog oscilloscopes if need example signal delay related to trigger. Just 2m more cable to signal path than to ext trig path and you have delayed signal 10ns. I have used this many times if rare some ns pulses need look so that also front of pulse is displayed.  If scope have 500ps/div it is very nice if delay can be something like 1ns-2ns  delayed.  Now trigger event can see 2-4div from left. Of course some scopes have also delay lines but not so many have adjustabe delay between signal and trig so it need many times make outside of scope. This is normal practice. Today digital scopes are different cases, they have pretrig capturing. But sometimes they also need timing adjustment. Many times channels have time difference.  It can adjust with short coax line. 0,1ns need 2cm.

In my GPS references (1 trimble and 2 HP  (better if 3 equal but I do not have)  I have  set antenna cables lenght so that it do not make so much error to real GPS time.  Today they have same antenna and so also antenna cable delay is same for each others.  (now they see always nearly same satellites exept small differencies becouse variations in receiver noises and sensitivity)
In short time GPS is very inaccurate but 6 -  24hour average is good for check (and adjust) some Rb references.

Cern and this study peoples do not really go this kind of mistakes. They are not kindergard level.
But where is error or are ther?

Some time ago Chinese students find design mistakes in CERN.

Maybe we can wait chinese studedts look this case also if there is some mistakes.  ;)   :D

(gravitation)
« Last Edit: November 20, 2011, 09:30:37 am by rf-loop »
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Online 0xdeadbeef

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Re: Neutrino experiment repeat at Cern finds same result.
« Reply #11 on: November 20, 2011, 10:07:44 am »
About that supernova argument: the supernova 1987A was detected first by several Neutrino detectors over the world. Only three hours later it was observed by telescopes. Which doesn't mean that neutrinos are faster than photons, since the neutrino burst probably happened before the photon emission, but for sure it doesn't prove that neutrinos are slower than photons.
Furthermore obviously only one of the detectors had an exact time sync, so measuring the speed of these neutrinos was not really possible by comparing their arrival at different detectors. Even with a reliable time base, the low and varying sensitivity of the involved detectors would have made the measurement pretty unreliable.

Compared to that, the OPERA data seems much more reliable. Of course there could still be a systematic measurement fault. But honestly, after the re-evaluation of the MINOS experiment, it seems likely that neutrinos can indeed travel faster than photons could do in a vacuum. Where "travel" includes taking shortcuts or whatever.
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Offline tbscope

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Re: Neutrino experiment repeat at Cern finds same result.
« Reply #12 on: November 20, 2011, 12:17:45 pm »
In E=mc², who said that c needs to be the speed of light?
Maybe we were always wrong and c actually is the speed of neutrinos?
 

Offline amspire

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Re: Neutrino experiment repeat at Cern finds same result.
« Reply #13 on: November 20, 2011, 12:57:34 pm »
Cern and this study peoples do not really go this kind of mistakes. They are not kindergard level.
But where is error or are ther?

To be fair to them, they did a very thorough check on the time synchronization between Cern and the Italian lab. They got an independent company in, and they double checked the
GPS time against a portable atomic clock, and an optical cable link between the two labs.  They have got the errors low enough to be able to sense the continental drift. With the portable atomic clock, they can easily get the two clocks sync error to much less then the 10nS specification they have for the Opera experiment.

So if there is an error, it is more likely to be an actual mistake, rather then a GPS error. It will be a very complex system at both ends, and we all know how easy it is to discover errors we never even suspected. Like something that is in the circuit that everyone thinks is not in the circuit. Or an error in communication between two different teams of scientists.

 

Offline SoftwareSamurai

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Re: Neutrino experiment repeat at Cern finds same result.
« Reply #14 on: November 20, 2011, 03:13:21 pm »
In E=mc², who said that c needs to be the speed of light?
Some yahoo named Einstein. (Tasmanian, right guys? ;) )

Maybe we were always wrong and c actually is the speed of neutrinos?
Well...no.

If c was NOT ~299,792,458 m/s then there would be TONS of experimental failures at every atom smasher in the world. Theoretical calculations would yield such large delta errors compared to their experiments that scientists everywhere would be jumping out their windows in fits of insanity.

Okay, perhaps not that bad, but still...

The speed of light has been measured so many times in so many ways that there's very little doubt as to its value. (At least, locally in our solar system.) And E = mc2 has been scrutinized by minds vastly superior to ours and still given a thumbs-up for accuracy. I trust all of those vastly superior minds telling me that E = mc2, where c is the speed of light, is correct.
 

Offline SoftwareSamurai

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Re: Neutrino experiment repeat at Cern finds same result.
« Reply #15 on: November 20, 2011, 03:25:21 pm »
To be fair to them, they did a very thorough check on the time synchronization between Cern and the Italian lab. They got an independent company in, and they double checked the
GPS time against a portable atomic clock, and an optical cable link between the two labs.  They have got the errors low enough to be able to sense the continental drift. With the portable atomic clock, they can easily get the two clocks sync error to much less then the 10nS specification they have for the Opera experiment.
I don't doubt their clocks; Synchronizing clocks is sophomore level stuff. I have no doubt these people are well above sophomore level.

So if there is an error, it is more likely to be an actual mistake, rather then a GPS error. It will be a very complex system at both ends, and we all know how easy it is to discover errors we never even suspected. Like something that is in the circuit that everyone thinks is not in the circuit. Or an error in communication between two different teams of scientists.
I think they're either detecting neutrinos that aren't generated by CERN (or more precisely, not generated by CERN expressly for this experiment - perhaps being generated in another part of CERN by chance?) or their experimental setup has a flaw somewhere. (Like rf-loop suggests, all it takes are some wires being slightly longer than designed to throw off 60-some ns of timing somewhere.)

Perhaps what they really need is some way to generated both photons AND neutrinos at the same time, let them race down a long tube together, then measure BOTH of them as they cross the finish line. It would be fascinating to see if photons end up 60 ns "early" as well!
 

Online 0xdeadbeef

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Re: Neutrino experiment repeat at Cern finds same result.
« Reply #16 on: November 20, 2011, 03:47:17 pm »
I think they're either detecting neutrinos that aren't generated by CERN (or more precisely, not generated by CERN expressly for this experiment - perhaps being generated in another part of CERN by chance?)
If you look at the experiment setup, I think this can be safely excluded.

or their experimental setup has a flaw somewhere. (Like rf-loop suggests, all it takes are some wires being slightly longer than designed to throw off 60-some ns of timing somewhere.)
Then the MINOS experiment seems to have the same flaw. They calibrated all of their devices and put a lot of thought into it. It's highly unlikely that something as simple as a wrong cable is the problem. Don't forget that 60ns is quite a lot today and these guys are familiar with very short time spans. Let's just wait and see until the experiment is repeated by other locations.

Perhaps what they really need is some way to generated both photons AND neutrinos at the same time, let them race down a long tube together, then measure BOTH of them as they cross the finish line. It would be fascinating to see if photons end up 60 ns "early" as well!
Building a straight evacuated loop of 730km length could prove difficult.
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Offline rf-loop

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Re: Neutrino experiment repeat at Cern finds same result.
« Reply #17 on: November 20, 2011, 06:40:22 pm »
(Like rf-loop suggests, all it takes are some wires being slightly longer than designed to throw off 60-some ns of timing somewhere.)

I have not the slightest doubt that this level of science they are doing a completely trivial error.

Sometimes it is helpful to use the cable delay line when making measurements.
In this context, it just came to mind as an aside.
If practice and theory is not equal it tells that used application of theory is wrong or the theory itself is wrong.
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Online 0xdeadbeef

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Re: Neutrino experiment repeat at Cern finds same result.
« Reply #18 on: November 20, 2011, 07:02:22 pm »
When working with a particle collider, you have to be able to cope with times in the picoseconds range. So 60ns are quite a lot. Any commercial GPS receiver has to be accurate to the ns level. A 1GHz risc processor could execute 60 commands in that time. It's really, really hard to believe the LHC people made any kind of trivial mistake of that magnitude.
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Offline rf-loop

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Re: Neutrino experiment repeat at Cern finds same result.
« Reply #19 on: November 20, 2011, 08:30:08 pm »
How they exactly synchronize clocks?
I have not seen any data how they exactly do time synch for used clocks.
(it is extremely difficult)
If practice and theory is not equal it tells that used application of theory is wrong or the theory itself is wrong.
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Offline SoftwareSamurai

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Re: Neutrino experiment repeat at Cern finds same result.
« Reply #20 on: November 20, 2011, 09:53:57 pm »
When working with a particle collider, you have to be able to cope with times in the picoseconds range. So 60ns are quite a lot. Any commercial GPS receiver has to be accurate to the ns level. A 1GHz risc processor could execute 60 commands in that time. It's really, really hard to believe the LHC people made any kind of trivial mistake of that magnitude.
Yes, it is hard to believe. Then again, we recently had a group claim to have "seen" the higgs, only to have their data reviewed by another group which showed they actually didn't detect any such particle due to a flaw in their statistical math.

I'm not saying these people are sophomoric in their craft. Far from it. Rather, I'm saying that such errors happen to even the brightest among us.

 

Online 0xdeadbeef

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Re: Neutrino experiment repeat at Cern finds same result.
« Reply #21 on: November 20, 2011, 11:39:49 pm »
Then again, we recently had a group claim to have "seen" the higgs, only to have their data reviewed by another group which showed they actually didn't detect any such particle due to a flaw in their statistical math.
Maybe I'm mixing this up and I'm too lazy to search, but I remember this differently. One group said they found an interesting anomaly in their data but stated it was not evident and could be also just that: an interesting anomaly. And later analysis showed it was.

I'm not saying these people are sophomoric in their craft. Far from it. Rather, I'm saying that such errors happen to even the brightest among us.
I'm not quite sure how anybody would use the term "sophomoric" in this context. The LHC scientists presented their results extremely humble and cautious. The held a press conference to explain how they set up the measurement and calibration and asked everybody to review them. Of course they did this only after checking their methods again and again and again. Now they even repeated their measurement and nobody on this whole wide world could tell them what was wrong with their setup. So to assume they did a trivial mistake or didn't consider cable lengths is a bit bold to be frank.

Besides, it looks like the little fellows really make some FTL jumps:
http://www.science20.com/alpha_meme/opera_confirms_faster_light_neutrinos_and_indicates_ultra_superluminal_small_initial_jumps-84774
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Offline SoftwareSamurai

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Re: Neutrino experiment repeat at Cern finds same result.
« Reply #22 on: November 21, 2011, 01:30:15 am »
Yes, you do remember the same group I was talking about. Perhaps the news media over-exaggerated their claim to finding the higgs (or some new particle), but in any event it was a case of one group of well educated scientists making a fundamental mistake in their math.

When I use the term sophomoric, I mean it in the context of someone who has knowledge and experience in their area of expertise, but still ends up makes a fundamental mistake. Not necessarily immature, but more along the lines of overconfidence. And I believe this is a prime case of a group of well educated scientists being overconfident in presenting their conclusions.

Now, as Phil Plait mused, perhaps what they've "found" is a different form (flavor?) of neutrinos, ones that don't come from a supernova. I find that hard to believe that CERN could produce such drastically different neutrinos than a whole supernova, but I'm willing to give it consideration for the sake of argument. Then again, perhaps they've actually discovered a tachyon that appears to be (or generates) a neutron when it "hits" their detectors. I'd be willing to believe THAT theory before I believe that neutrinos can travel FTL. (The standard model would demand that if neutrinos can travel FTL, then electrons can as well, and so far we've never seen an electron travel FTL.)

Right now it appears that most scientists reviewing these results are mostly questioning the clocks, the distance, and everything related to velocity calculations, which is why I suggested that perhaps they've made a fundamental mistake, such as calculating the distance traveled 18 m longer than it truly is. Other possible affects such as frame-dragging is, IMHO, stretching it a bit. Yeah frame-dragging is real, but could it really affect a neutrino to such a degree? I find that hard to believe, considering they interact so weakly with matter in the first place.

Now, as to the possibility of neutrinos doing an "initial FTL jump" - Well I suppose that could be possible. But to prove that they simply need to move the detectors really close to the source and take more measurements. If the number of neutrinos drops off significantly the closer they get (assuming no change in the source emissions), then that would be proof. If true, I can see thousands of scientists scratching their heads trying to explain THAT idea.

Another possibility, one that I thought might have some legs, is the idea that a neutrino oscillating between tau and muon might go FTL during the transition period between the two flavors. That is, it would be sub-luminal when it's a tau, then lose its higgs causing it go super-luminal (transforming into ?), then regains its higgs, transforms into a muon neutrino and dropping to sub-luminal again. The only problem with that theory is, again, supernova records just don't support such a large FTL velocity as what they suggest their data says.

It's also been suggested that nothing travels FTL, but the space-time fabric itself could have a velocity, and to an outsider anything traveling inside such a piece of space-time fabric would appear to be FTL. That's an excellent idea, and when warp engines get invented, I certainly hope to own a space ship with such an engine. But could such tiny collisions at CERN create tiny pieces of space-time traveling along the same path as the neutrinos, and "carry" them along, causing us humans to think they've gone FTL? Hmmm... Something to think about.
 

Offline amspire

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Re: Neutrino experiment repeat at Cern finds same result.
« Reply #23 on: November 21, 2011, 02:11:08 am »
It's also been suggested that nothing travels FTL, but the space-time fabric itself could have a velocity, and to an outsider anything traveling inside such a piece of space-time fabric would appear to be FTL. That's an excellent idea, and when warp engines get invented, I certainly hope to own a space ship with such an engine. But could such tiny collisions at CERN create tiny pieces of space-time traveling along the same path as the neutrinos, and "carry" them along, causing us humans to think they've gone FTL? Hmmm... Something to think about.

The whole Big Bang theory, and the concept of "Background Radiation" depends on the fact that space-time can expand at much faster then the speed of light. So the distance between two separated objects in space-time can easily be increasing at hundreds or millions or billions of times the speed of light, but no object would be traveling faster then the speed of light in space-time. At this point, the physicist usually pulls out a balloon and inflates it to try explain what he means.

Richard
 

Offline JuKu

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Re: Neutrino experiment repeat at Cern finds same result.
« Reply #24 on: November 21, 2011, 08:16:36 am »
How they exactly synchronize clocks?
I have not seen any data how they exactly do time synch for used clocks.
By transportable atomic clocks.
Quote
(it is extremely difficult)
No, it is not.
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