CERN team claims measurement of neutrino speed >c

[miguel_barros]

Does anybody know if the neutrinos sent from CERN to Gran Sasso have their speed measured beofre the leave the CERN facility?
CERN shoot their hadrons around at 99.9% the speed of light?
If the neutrinos are also 'built up' to this speed then for the readings that they are getting at Gran Sasso (faster than speed of light), the neutrinos would not only travel faster than light but also be accelerating without additional energy?

That's not how it works

They have 2 syncronized clocks and a light speed baseline for the TOF

then they use the Proton Waveform and the timestamp to establish a maximum likehood function that should match the neutrino function at arrival

They take the arrival and match it and test it against the speed of light baseline.

As I mentioned above this could lead to the 60 ns anomaly being the fact that there is no magic stoper and the aditional 18 meters of the "HADRON STOPPER" being in fact a new (if less than perfect) target for the production of kaons and their decay to muon neutrinos.

 

[Imax]

A possible experiment to confirm OPERA results:

What could happen, hypothetically, if the OPERA results were valid, and you could drop a neutrino emitter down a black hole?

 

[lalbatros]

I think you have missed key elements of the paper:

In this experiment, neutrinos seem to behave, during the 735 km travel, either as tachyons or as they had a pseudo-tachyonic behavior when transversing a material, like photons in meta-materials [9, 10] with negative refractive index or less than unity, that allows an apparent superluminal propagation without violating causality.​

[emph added]

and with reference to phase velocity:

As vg > vp, the medium would cause the speed of only certain Fourier components of neutrino wavefunction in it to be larger than the speed of light in vacuum for a band of neutrino oscillation frequencies obeying the Majorana condition p ≥ kc, but seems to be forbidden by CG effect for a standard neutrino.​

Mere phase-velocity would not allow FTL communication, and the implications of the paper is that Einstein was, again, correct: nothing communicative can travel faster than c in vacuo.

I understand that the OPERA experiment measured particles velocities, which are group velocities.

A refractive index represents an interaction between a wave or a particle and matter, rocks here.

For example, the refractive index of homogeneous classical plasmas can be studied in full detail from the laws of classical mechanics and electrodynamics. The refractive index of a plasma is caused by the interaction and response of the plasma (the matter) to the wave. Usually (necessarily), this index of refraction changes with the frequency (energy), and causality then also implies an absorption of the wave.
A particle point of view or a quantum dynamics approach (necessary for plasmas below the fermi level) does not change the global picture.

In summary: a refractive index different from 1, should imply an interaction with matter as well as an absorption.

Knowing the extremely weak interaction of neutrinos with matter, I can't see how this could lead to a refractive index, even 10^-5 close to 1.

If the neutrinos have a FTL light, this can in no way be "explained" by a "refractive index".
The presence of rocks should therefore play no role in the FTL velocity of neutrino, and the same result should be expected for neutrino propagating through vacuum.
Therefore this "refractive index" is even not related to the "rocks", which is a strange syntax for a refractive index.
You could of course call v/c a "refractive index", but this would explain nothing.
I could as well say that I am driving my car at a very low refractive index.

 

[miguel_barros]

Just a small correction on my last comment

The distortion caused by the second target (hadron stopper) might be much bigger on the muon (initial image) sensors than on the neutrinos detected at OPERA.

I would really like to see the result of a run without the primary target T40-s, just the muon image and detected neutrinos from the Hadron Stopper.

Maybe then they would see that the difference between the 1048 ns blind calibration and their individual effects of around 1000 ns is the 60 ns hadron stopper distortion.

 

[lalbatros]

That's not how it works

They have 2 syncronized clocks and a light speed baseline for the TOF

then they use the Proton Waveform and the timestamp to establish a maximum likehood function that should match the neutrino function at arrival

They take the arrival and match it and test it against the speed of light baseline.

As I mentioned above this could lead to the 60 ns anomaly being the fact that there is no magic stoper and the aditional 18 meters of the "HADRON STOPPER" being in fact a new (if less than perfect) target for the production of kaons and their decay to muon neutrinos.

Miguel,

The only delay that matters is the time elapsed between a signal on the Beam Current Transformer (BCT) and the OPERA detector in Gran Sasso.

It does not matter that the conversion from protons to kaons and from kaons to neutrinos occurs further downstream. This is because the protons and kaons have high energies and travel extremely close to the speed of light.

In particular, additional kaons that would be produced in the Hadron Stopper would in no way modify the result. Those neutrinos originating from the Hadron Stopper should come exactly at the same time in Gran Sasso than other neutrinos originating from the main target.

This is precisely the magic of the constancy of the speed of light.
But it might be challenged now.

Michel

 

[miguel_barros]

I assume you haven't read my last correction.

Most likely those "Hadron Stop Born" muons don't have time to decay, but there are plenty and they do show up on the muon monitors.

Furthermore not all protons have the same energy and so the fraction of speed of light they travel is proportional to their energy.

Fore-runners and laggards will skew the CBT timestamped muon "origin" picture, specialy if one assumes that the only origin of muons is at the Target (1 km before the Hadron Stop)

How does it affect the result? Maybe that's the reason they had to do a "blind calibartion" adding 1048 ns to the baseline when the explained items amounted to (in their own words) "~1000 (ns)".

Maybe it skews the medium point of decay.

It will most likely distort the picture being fitted to the "arrival" signal.

If any, or all, of these effects take place the 60 ns difference is trivial.

BTW, as a simple rule I would not consider publishing anything stating that a "blind calibration" had been used because the internal delays added up to ~1.000 and I hadn't found out why I needed 1048.

Specialy when it finishes with a 60 ns revolutionary conclusion.

 

[BobCastleman]

This will seem hopelessly simplistic, but aren't they saying that the neutrinos arrived sooner than light if the light had traveled the same path? How can you say that a photon leaving the neutrino source at the same moment, traveling the same path, would arrive later (or sooner) than the neutrinos? Aren't they comparing an ACTUAL measurement with a theoretical value? To say that it actually traveled faster than light would one not have to measure both the photons and the neutrinos under the same conditions?

 

[Passionflower]

This will seem hopelessly simplistic, but aren't they saying that the neutrinos arrived sooner than light if the light had traveled the same path? How can you say that a photon leaving the neutrino source at the same moment, traveling the same path, would arrive later (or sooner) than the neutrinos? Aren't they comparing an ACTUAL measurement with a theoretical value? To say that it actually traveled faster than light would one not have to measure both the photons and the neutrinos under the same conditions?

The thing is, they claim to know the exact coordinate distance and time the neutrinos traveled, thus if you know the distance and the time you know the velocity. It is claimed this velocity is faster than light.

Thus the questions are:
- Is the coordinate distance correct?
- Is the elapsed coordinate time correct?

 

[BobCastleman]

The thing is, they claim to know the exact coordinate distance and time the neutrinos traveled, thus if you know the distance and the time you know the velocity. It is claimed this velocity is faster than light.

Thus the questions are:
- Is the coordinate distance correct?
- Is the elapsed coordinate time correct?

But the experiment boils down to neutrinos traveled from point A to point B in some time X. In theory, light would travel from the SAME point A to the SAME point B in some time X-n. But they can't measure light moving from the same A to B, they can only calculate what it should be, no? Without the actual measurement of light, then they can only say that the neutrinos were faster than the theoretical speed of light along THAT path. But unless they shoot a beam of photons from that A to that B, and actually measure it, their claim of super luminal speed is "on paper", as it were.

Haven't other observations of neutrinos confirmed sub-luminal speeds? Isn't it more Occam's Razorish to assume that the conditions of the experiment are the issue rather than overturning a fundamental piece of physics?

I do understand this is a very intriguing observation. Quite disruptive, one might say. It will be fascinating to watch it lay out.

 

[Aether]

But they can't measure light moving from the same A to B, they can only calculate what it should be, no?

It is not possible to actually measure the one-way speed of light in any way that is consistent with Special Relativity. Neither is it possible to "calculate what it should be". What actually happens is that the one-way speed of light is assumed to be c, and a coordinate system (an inertial frame) is constructed wherein this assumption automatically holds true. The two-way speed of light (isotropy) is what can actually be measured.

Without the actual measurement of light, then they can only say that the neutrinos were faster than the theoretical speed of light along THAT path. But unless they shoot a beam of photons from that A to that B, and actually measure it, their claim of super luminal speed is "on paper", as it were.

That's right. In their paper, the OPERA team claims:

An early arrival time of CNGS muon neutrinos with respect to the one computed assuming the speed of light in vacuum of (60.7 ± 6.9 (stat.) ± 7.4 (sys.)) ns was measured.

 

[BobCastleman]

It is not possible to actually measure the one-way speed of light in any way that is consistent with Special Relativity. Neither is it possible to "calculate what it should be". What actually happens is that the one-way speed of light is assumed to be c, and a coordinate system (an inertial frame) is constructed wherein this assumption automatically holds true. The two-way speed of light (isotropy) is what can actually be measured.

If you cannot measure the speed of light one-way, then how can you accurately transmit the information to the other end that signals the start time? If point A initiates an event, then point B needs to know the time of initiation. Basically, the neutrinos arrive before the signal of the start time, since the signal is being bounced off a satellite, or sent over a fiber optic cable or some such thing and is not traveling at c.

It must be a tricky calculation, seeing as both ends of the experiment are accelerated reference frames via the rotation of the earth. Wouldn't they they be under different accelerations based on their latitude and altitude? Wouldn't the entire path of the transmitted start signal also be subject to acceleration issues in the calculations? I assume they had to use numerical methods to do all those calculations. It would be ironic to find that the intrinsic errors in computerized floating point arithmetic caused the anomaly.

 

[Angry Citizen]

Without the actual measurement of light, then they can only say that the neutrinos were faster than the theoretical speed of light along THAT path. But unless they shoot a beam of photons from that A to that B, and actually measure it, their claim of super luminal speed is "on paper", as it were.

I may be mistaken, but I believe this is a non-issue. The neutrinos violated c, not the speed of light. That should not be happening under the conditions of SR.

 

[BobCastleman]

I may be mistaken, but I believe this is a non-issue. The neutrinos violated c, not the speed of light. That should not be happening under the conditions of SR.

Yes, I understand that now.

 

[Passionflower]

Yes, I understand that now.

Then you understand more than I as in my understanding c is the speed of light in vacuum.

 

[ChrisPhy]

Given the small (to me it's small) amount measured beyond c, and where speed is just distance / time...
1) How is it they are so certain to the exact distance involved in this experiment ?
2) How did they rule out possibility that with the slight increase in energy density along the path of the experiment that the length did not momentarily compress by a fraction of a mm. ?

 

[Aether]

If you cannot measure the speed of light one-way, then how can you accurately transmit the information to the other end that signals the start time?

Each relevant event is time-stamped using a clock that is located nearby, and the travel time for each neutrino depends on how the clocks at each end of the experiment are synchronized.

If point A initiates an event, then point B needs to know the time of initiation.

Yes, but they don't need to know this right away.

Basically, the neutrinos arrive before the signal of the start time, since the signal is being bounced off a satellite, or sent over a fiber optic cable or some such thing and is not traveling at c.

In fact, the time-stamps from CERN are not immediately made available to the people at Gran Sasso. They only get to see that information after they have reported the time-stamps for the neutrino detections.

It must be a tricky calculation, seeing as both ends of the experiment are accelerated reference frames via the rotation of the earth. Wouldn't they they be under different accelerations based on their latitude and altitude? Wouldn't the entire path of the transmitted start signal also be subject to acceleration issues in the calculations? I assume they had to use numerical methods to do all those calculations. It would be ironic to find that the intrinsic errors in computerized floating point arithmetic caused the anomaly.

Sure, its a tricky calculation for many reasons, but that's nothing that can't be dealt with given enough time and money.

 

[ChrisPhy]

Given the small (to me it's small) amount measured beyond c, and where speed is just distance / time...
1) How is it they are so certain to the exact distance involved in this experiment ?
2) How did they rule out possibility that with the slight increase in energy density along the path of the experiment that the length did not momentarily compress by a fraction of a mm. ?

SORRY,...off by ^3 orders using calculator,.60 billionths of sec yields a non-so-small distance. Please disregard...

 

[BobCastleman]

Each relevant event is time-stamped using a clock that is located nearby, and the travel time for each neutrino depends on how the clocks at each end of the experiment are synchronized.

How do they prove synchronization?

They only get to see that information after they have reported the time-stamps for the neutrino detections.

Is there a reason for this? Seems an odd protocol.

Sure, its a tricky calculation for many reasons, but that's nothing that can't be dealt with given enough time and money.

That's funny. Time and money can't seem to help a flailing economy. I guess physics is easier.

 

[ChrisPhy]

Dumb question probably. But how often is the distance between source and destination in this experiment measured ? The Earth is pretty big, is it not possible that it's surface is simply flexing all the time, and that sometimes the distance between the points as a direct through-earth straight line is upwards to 60 ft less than other times ?

 

[mkj]

In the least number of words can anyone explain for me if the results presented in paper are right or wrong. if right does it contradict the law of physics. if wrong why?

 

[Aether]

Then you understand more than I as in my understanding c is the speed of light in vacuum.

We define the one-way speed of light in vacuum to be c as a step along the way in constructing inertial frames, but that is an entirely untestable hypothesis within the framework of Special Relativity. That is why the constancy of c has to be a postulate within the standard formulation of Special Relativity.

The two-way speed of light can actually be measured beause we can use the same clock to time-stamp emission and reception events, and therefore clock synchronization is not an issue.

 

[Passionflower]

We define the one-way speed of light in vacuum to be c as a step along the way in constructing inertial frames, but that is an entirely untestable hypothesis within the framework of Special Relativity. That is why the constancy of c has to be a postulate within the standard formulation of Special Relativity.

The two-way speed of light can actually be measured beause we can use the same clock to time-stamp emission and reception events, and therefore clock synchronization is not an issue.

Yes , so what is your point?

 

[Aether]

How do they prove synchronization?

They don't. That is why the constancy of c is a postulate within the standard formulation of Special Relativity.

Is there a reason for this? Seems an odd protocol.

That helps to prevent the people at OPERA from biasing their analysis (blind/double-blind study).

That's funny. Time and money can't seem to help a flailing economy. I guess physics is easier.

Time and money only helps when it is applied intelligently.

 

[Aether]

Yes , so what is your point?

To demonstrate the difference between c as an untestable definition (postulate), and 'the speed of light' as an actual measurement.

 

[Aether]

...how often is the distance between source and destination in this experiment measured ? The Earth is pretty big, is it not possible that it's surface is simply flexing all the time, and that sometimes the distance between the points as a direct through-earth straight line is upwards to 60 ft less than other times ?

They measure this distance constantly. You should look at the paper (start with Fig. 7).

The high-accuracy time-transfer GPS receiver allows to continuously monitor tiny movements of the Earth’s crust, such as continental drift that shows up as a smooth variation of less than 1 cm/year, and the detection of slightly larger effects due to earthquakes. The April 2009 earthquake in the region of LNGS, in particular, produced a sudden displacement of about 7 cm, as seen in Fig. 7. All mentioned effects are within the accuracy of the baseline determination. Tidal effects are negligible as well.

 

[Aether]

In the least number of words can anyone explain for me if the results presented in paper are right or wrong.

No.

...if right does it contradict the law of physics. if wrong why?

It right, then it would be something new, but nobody knows for sure whether the result is right or wrong. It will have to stand up to the test of time before anyone can know that.

 

[ChrisPhy]

They measure this distance constantly. You should look at the paper (start with Fig. 7).

Thanks, I didn't even know the paper was available. Thanks.

 

[ChrisPhy]

They measure this distance constantly. You should look at the paper (start with Fig. 7).

! - disregard::
Just read the released PDF regarding results. Thanks. The document contained enough detail for me to understand the methodology of how the timing was accurately 'synched' however details of how the distance between the points is confidently accurate is missing. The paper simply makes the assertion that the margin of error is 20cm. Accurate distance calculations are probably considered second nature to most and that's why it wasn't mentioned, but does anyone know the details, specific details, of how this distance is determined to within 20cm (please don't tell me it is the inverse, by measuring how long signals take between the two assuming c, because then we may just simply be looking for why these signals were slightly SLOWER than c) Can someone help me understand. Thanks

 

[ChrisPhy]

Sorry, I re-read the intro again, and it contained numerous mentions of the 'dedicated geodesy campaign' and a brief explanation, I'll do some research on the precise methods elsewhere, sorry too quick to ask... Disregard last question.

 

[OCR]

Seems an odd protocol.

Indeed.

That helps to prevent the people at OPERA from biasing their analysis (blind/double-blind study).

Seems to be working, too, wrt blind/double-blind... IMO.

It sure looks like somebody isn't seeing...
OCR... lol