CERN team claims measurement of neutrino speed >c

[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

 

[miguel_barros]

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.

The distance from the FOCAL POINT (T40S target) to OPERA seems FLAWLESS

http://www.google.com/url?sa=t&rct=j&q=opera%20geodesy&source=web&cd=2&ved=0CCEQFjAB&url=http%3A%2F%2Foperaweb.lngs.infn.it%2FOpera%2Fpublicnotes%2Fnote132.pdf&ei=zAXQTrb5HMeN-was_NzNDg&usg=AFQjCNG_yCiIm6YGOfACSORKKKozV-syAQ&cad=rja

Nevertheless I wouldn't put the rest of calibrations and assumptions on the same level.
(as stated before)

 

[Angry Citizen]

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

That's correct, but the point I was trying to make is that c is not always the actual speed of light - c is the speed of light in a vacuum. But light actually slows down when it passes through material. Since these neutrinos are apparently going faster through a material than light could travel in a vacuum, this experiment is very interesting.

The idea of the 'cosmic speed limit' discussed in popular science is actually a great metaphor. Nothing can exceed c, even though sometimes particles can travel faster than the speed of light. An example of the latter is Cherenkov radiation. c has nothing to do with the speed of light, although of course the speed of light has everything to do with c. It's an independent value. The two quantities do not have to match, and in fact when light passes through a medium, they never do.

Apologies if this is all elementary, and if I'm repeating things you've heard ages ago. I just wish to fully explore the significance of this result by illustrating its impossibility under special relativity.

 

[danR]

I don't get the feeling we're looking at the same paper. Clearly they are generalizing the notion of 'refractive index', but that is nothing new. There is an acoustic 'refractive index', for example.

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

>>A classical refractive index indeed implies interaction (EM) interaction with matter. It does not require absorption, unless I misunderstand your meaning of absorption. How can light travel through glass if it's absorbed? Or sound with respect to an acoustic refractive index?​

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.

>>I'm sure the authors are not talking classical refractive indices (EM), but something analogous.​

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.

>>It is precisely analogous to light propagating through a vacuum vs light propagating through glass. The main egregious, and admittedly speculative, element being a negative refractive index.​

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.

>>This part has lost me entirely. Have you read the paper?​

late Edit: sorry, I wasn't paying attention to the paper myself. They are specifically saying group-velocity >c. Apart from that, I don't see how I can speak better for their paper, speculative though it may be. It is the CERN results they are speaking to. That said, I'm not sure how the new, shorter, pulses would strengthen their explanation.

It's certainly an extraordinary explanation. But to alter an old truism: extraordinary evidence (may) require extraordinary claims.

 

[OnlyMe]

late Edit: sorry, I wasn't paying attention to the paper myself. They are specifically saying group-velocity >c. Apart from that, I don't see how I can speak better for their paper, speculative though it may be. It is the CERN results they are speaking to. That said, I'm not sure how the new, shorter, pulses would strengthen their explanation.

By using the short pulse neutrino beam they rule out some of the previous speculations for some systematic error. They also are able to in essence time single neutrino velocities rather than a group velocity. Kind of...

In the original data there was a long start time for the neutrino beam and a long detection period. This added to uncertainty of the actual individual velocity. By cutting the proton beam to 3 ns, that both shortened the start time and the detection time. Also I believe this was a test run for the modified experiment. Given the results, it is my understanding that a proton beam will be made available again next year for a long experiment.

I also understand that MINOS is also gearing up to run the experiment.

 

[new_r]

Why everywhere data is written in seconds and distance.
Just let's calculate it in terms of c+v
and you will get v = about 8km/s

That is exactly the amount of velocity necessary to spin circularly around the Earth.
I think some type of mater (something like dark energy or dark mater or something unknown)
spinning around big masses in all possible directions and drags neutrinos with it.

 

[miguel_barros]

Another 8 km/s of Earth spin?

That would be the worst possible explanation

Not only could neutrinos go faster than light but their speed wouldn't be invariant.

 

[Galteeth]

Layman question: Does the gravitational curve of the Earth have effect on the neutrinos path?

 

[new_r]

Layman question: Does the gravitational curve of the Earth have effect on the neutrinos path?

If I am right this would be equivalent to Shapiro delay which is far too small for this case.

 

[nitsuj]

Another layman question: How do they know how long the neutrino's journey was in time and distance? And which of those two would be more difficult to measure?

 

[Vanadium 50]

Before posting in this thread, we'd like to ask readers to read three things:

• The PF Rules. Don't forget the section on overly speculative posts.
• The paper http://arxiv.org/abs/1109.4897
• he previous posts in this thread

We think this will make the discussion go smoother.

V50, for the Mentors.

 

[Centri-Fagin]

So they don't really know how fast they are going before they leave CERN?

 

[new_r]

Not only could neutrinos go faster than light but their speed wouldn't be invariant.

Yes, you are right, not invariant.
Do you know to which directions neutrinos will be send by other laboratories?
If some of new experiment's will be along the Earth rotation will be nice to compare the results.

 

[miguel_barros]

But at the direction of CERN to OPERA you wouldn't get the full rotacional effect of 8km/s it's SW not W. And they don't follow the earth, they go right through, neutrinos don't interact much.

Sorry but can't see your effect happening.

 

[lalbatros]

Why everywhere data is written in seconds and distance.
Just let's calculate it in terms of c+v
and you will get v = about 8km/s

That is exactly the amount of velocity necessary to spin circularly around the Earth.
I think some type of mater (something like dark energy or dark mater or something unknown)
spinning around big masses in all possible directions and drags neutrinos with it.

The equatorial radius of Earth is: 6,378.1370 km . (1)
The Earth sidereal day is 23.9344696 h . (2,3)
The Earth average distance from the sun is 150 million kilometers. (4)

From this we can get:

The sidereal Earth rotational speed: 1674 km/h = 0.465 km/s
The Earth speed around the sun: 107589 km/h = 29.9 km /s

What's this story with these 8 km/s?
Is that one more Pentcho Valev story?
I don't get it.

Michel

1/ http://en.wikipedia.org/wiki/Earth_radius
2/ http://en.wikipedia.org/wiki/Sidereal_time
3/ http://www.google.com/search?q=sidereal+day
4/ http://en.wikipedia.org/wiki/Earth's_orbit

 

[miguel_barros]

Before putting to sleep one of my first doubts.

could someone:

1. confirm the coordinates of the proton release point (should be close to this point but any correction would be most welcome). This relates to the additional 730m tunnel

http://maps.google.com/maps?q=4http:%2F%2Fmaps.google.com%2Fmaps%3Fq%3D46.235,6.0425&ll=46.246039,6.070343&spn=0.003688,0.006899&t=h&z=17&vpsrc=6

2. Indicate the coordinates of the T40-S Focal point and muon deterctors

3.AND/OR the Coordinates of the OPERA detector (it should be on the western/northern side of the A24 at the campo imperatore level, close to this point)

http://maps.google.com/maps?q=4http:%2F%2Fmaps.google.com%2Fmaps%3Fq%3D46.235,6.0425&ll=42.445208,13.564435&spn=0.003935,0.006899&t=h&z=17&vpsrc=6

Any information (with or without source) would be apreciated

 

[new_r]

Thank you Michel for your post.
But I am not about the rotation of the Earth,
I am about possible rotation of some type of (dark) mater around the Earth.
Due gravitation particles of such matter would have velocity about 8km/s to hold circular motion.
We call it first space velocity in my language, but I am not sure how it names properly in English.

(For example second space velocity in my language is equal to escape velocity in English)

 

[BobCastleman]

Thank you Michel for your post.
But I am not about the rotation of the Earth,
I am about possible rotation of some type of (dark) mater around the Earth.
Due gravitation particles of such matter would have velocity about 8km/s to hold circular motion.
We call it first space velocity in my language, but I am not sure how it names properly in English.

(For example second space velocity in my language is equal to escape velocity in English)

Suppose we were in such a cloud of dark matter, wouldn't both ends of the experiment be equally affected as well as every point in between? Even if this dark matter accelerated the neutrinos, how did it accelerate them above c?

 

[new_r]

Suppose we were in such a cloud of dark matter, wouldn't both ends of the experiment be equally affected as well as every point in between? Even if this dark matter accelerated the neutrinos, how did it accelerate them above c?

I am not who can know everything. :)
Just a guess.
But apart of this:
If you would calculate overage velocity of c+v and c-v , where v is the first space velocity,
then you will get c-v^2 /c which is equivalent to Shapiro delay in this direction.

Similarly Shapiro delay can be calculated vertically if you will take v equal to escape velocity (sharp orbit of dark mater).

So maybe particles of such dark mater interact only when they moves to the same direction with neutrinos.
But with photon they interacts in both directions, therefore photon gets Shapiro delay.

 

[BobCastleman]

So maybe particles of such dark mater interact only when they moves to the same direction with neutrinos.
But with photon they interacts in both directions, therefore photon gets Shapiro delay.

I'm really new to this entire subject, but even to me, this seems overly speculative. Is there any force that acts in one direction like that? And further, acts in two directions on photons? Invoking special forces and unknown interactions doesn't clear things up. It just clouds the issue.

 

[Angry Citizen]

Is there any force that acts in one direction like that?

Friction. Perhaps dark matter has an opposite coulomb interaction to that of normal matter. But I agree it is far too speculative. Neutrino velocity exceeding c must first be confirmed before any serious attempts at theoretical explanation occur.

All I can say is, if c really has been broken, then I'm glad I'm not a physicist. For me, it'd be like watching everything we know about airplanes go 'poof', and us having to start back at square one...