CERN team claims measurement of neutrino speed >c

[Trenton]

Does anyone know the detail of this experiment? Certain things stick out as obvious questions, most notably the imposibility of measuring the 'one way' speed of light. The receiver could be running into the nutrinos shortening the journey time but the confirmation signal going the other way would be lengthened by the same amount. There is a good write up on this in Wikipedia.

The problem with the CERN thing is that there is no equivent path for the photons to travel alongside the nutrinos. The confirmation signal travels round the circumference of the globe, not directly through it. It also travels slightly sub c as it passing either through wire or air of varing pressure and thus varying refractive index.

I don't see how the nessesary rigor can be applied in this situation - unless I am missing something, which I admit I can be prone to!

But if the experiment is rigourous, I'd be willing to bet, as I mentioned on this site before, that this could be our best (most accurate) speed of light experiment yet. To a neutrino solid rock is probably a better eqivelent to a vacuum (less cross section thingy) than the vacuums we can create in the lab to time photons in.

I'm still with Einstein

 

[Vanadium 50]

Does anyone know the detail of this experiment?

Sigh...

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.

 

[nucl34rgg]

There's a point I'd like to make about how "this is like watching everything we know about airplanes go 'poof.'" If somehow magical fairies or some other previously undetectable thing made it impossible for our current theories of aeronautical engineering to be true, would anyone care? Would the planes we have magically stop working? The answer is no and so, for a practicing engineer, they could still probably use the same theories they used before but make note of the correction and apply it when and where it is SIGNIFICANT.

Keep in mind that most mechanical engineering makes excellent use of classical mechanics, something we now consider "false." Yet, we use the fruits of mechanical engineering every day, and we'd be idiots to throw everything we have away because it isn't 100% right. (Ask yourself if there is any way we could actually have a 100% correct theory obtained empirically and "proven" empirically, which is of course, a logically fallacious endeavor unless the empirical evidence is exhaustive, something impossible to achieve in our universe.)

In the same way, the result of this experiment, if it weren't due to some sort of experimental error, would open the door to new physics, and it would mean our previous theory was incomplete in some sense. However, the overwhelming number of experiments that support current models of relativity show us that even in the extremely miniscule chance that it is technically "wrong" or rather incomplete, it would still be a GOOD APPROXIMATION. That's the whole point. In the domain in which you are looking at, it is ok to make approximations if the error of your theory isn't significant numerically to your result.

 

[Aether]

The problem with the CERN thing is that there is no equivent path for the photons to travel alongside the nutrinos. The confirmation signal travels round the circumference of the globe, not directly through it. It also travels slightly sub c as it passing either through wire or air of varing pressure and thus varying refractive index.

I don't see how the nessesary rigor can be applied in this situation - unless I am missing something, which I admit I can be prone to!

Although it would be nice to be able to send a laser beam along the neutrino path between CERN and Gran Sasso, this is not necessary. By accurately measuring the distance between the two points, and by synchronizing the clocks properly, then the speed of light in vacuum between the two points will be c, and the speed of the neutrinos can be measured in proportion to c.

The one-way speed of light, and the one-way speed of the neutrinos, are not actually measured (or measurable), but the ratio of the two speeds is an actual measurement.

 

[gmack]

Many people here and elsewhere have already noticed that the delta-speed of Opera's neutrino is very close to the orbital velocity of GPS satellites.
My question is: does anyone know if the guys in Opera have looked for some correlation between neutrino arrival times and arrangements of GPS satellites hovering over LNGS at detection times ?
Finding some "regularity" of that kind would hint to some relativistic effect not properly taken into account, wouldn't it ?

 

[lalbatros]

Many people here and elsewhere have already noticed that the delta-speed of Opera's neutrino is very close to the orbital velocity of GPS satellites.
My question is: does anyone know if the guys in Opera have looked for some correlation between neutrino arrival times and arrangements of GPS satellites hovering over LNGS at detection times ?
Finding some "regularity" of that kind would hint to some relativistic effect not properly taken into account, wouldn't it ?

This animation from wikipedia shows that the GPS satellites used in the OPERA experiment probably had their speeds in many different directions. I don't see how a boost of 8 km/s could likely result for measurements along the CERN-Gran Sasso line. I take that as a pure coïncidence.

http://en.wikipedia.org/wiki/Global_Positioning_System

Nevertheless, it would be a useful exercice to use the oribital data of all these satellites to see if there would be an net average velocity as seen from the OPERA experiment. (or at least the satelllites that had played a role, which implies additional information)

A pitty that Galileo is not yet available to offer an alternative measurement.
Is there a Russian GPS system that could offer this alternative?

Some data about the GPS system that could help to evaluate an average satellite speed above Italy:

http://www.colorado.edu/geography/gcraft/notes/gps/gif/oplanes.gif
http://www.colorado.edu/geography/gcraft/notes/gps/gps.html

 

[new_r]

About clocks on satellite.
http://www.lifeslittlemysteries.com/faster-than-light-neutrino-relativity-gps-clocks-2104/

"OPERA responded to van Elburg's accusation. "The author [van Elburg] is not really taking into account special relativity (SR), but he is trying to compose the speed of the satellite with the speed of the radio waves, which makes no sense in SR," spokesman Pasquale Migliozzi told Life's Little Mysteries. "Composing speeds" is a special way of adding them together in special relativity."

 

[thenewmans]

The problem with the CERN thing is that there is no equivent path for the photons to travel alongside the nutrinos.

I’m just going to through this one out there. What if you put a half decent laser range finder on a jet flying at 30 or 40 thousand feet and flew it over CERN. With a cocktail napkin calculation, I’m guessing you could spot a jet flying over Gran Sasso. Every time you get a reading, both jets photograph the horizon to verify their position. I’m guessing the rangefinder uses light travel time. With that and the distance between the jets verified, you have essentially recreated the experiment using light. Feel free to rip it apart.

 

[Trenton]

Aether,

You state that "Although it would be nice to be able to fire a laser beam along the neutrino path between CERN and Gran Sasso, this is not necessary. By measuring the distance between the two points, and by synchronizing the clocks properly, then the speed of light in vacuum between the two points will be c, and the speed of the neutrinos can be measured in proportion to c.

The one-way speed of light, and the one-way speed of the neutrinos, are not actually measured (or measurable), but that _ratio_ of the two speeds is an actual measurement."

I personally doubt that the CERN people have failed to apply the most extensive rigor as they would fully aware of the consequences. It would be embarassing to say the least if it should turn out that something has been overlooked.

That said, I would like to know more about how they are synchronizing the clocks, purely because I can't figure out how to do it!

I did read the paper at http://arxiv.org/abs/1109.4897 but this only mentioned the accuracy benefits of shorter bursts of nutrinos.

 

[rorix_bw]

That said, I would like to know more about how they are synchronizing the clocks, purely because I can't figure out how to do it!

I did read the paper at http://arxiv.org/abs/1109.4897 but this only mentioned the accuracy benefits of shorter bursts of nutrinos.

In that paper, somewhere around page 8 to 10. Seriously though, we aren't your private secretary. The info is there in the paper, or at least enough information to enable you to do some very specific future research (hey, I don't know what you do and don't know, so don't know where to start!).

 

[rorix_bw]

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...

Science is about discovery. I'm sure most would be excited. Besides, the aircraft won't all suddenly fall out of the sky. And much of the stuff taught about aircraft is wrong anyway, like the equal transit fallacy (that tries to explain how they generate lift).

 

[Aether]

...I would like to know more about how they are synchronizing the clocks, purely because I can't figure out how to do it!

I did read the paper at http://arxiv.org/abs/1109.4897 but this only mentioned the accuracy benefits of shorter bursts of nutrinos.

Some details about how the OPERA team synchronized their clocks is given on the first half of page 9 of the paper. I am not otherwise familiar with this particuar method that they used to synchronize their clocks.

Einstein's clock synchronization procedure involves an exchange of signals at light speed, but that can't be used in this case because there is no line-of-sight path for photons between CERN and Gran Sasso. An equivalent procedure is "slow clock transport" where you synchronize two clocks at point A, and then transport one of the clocks slowly to point B.

 

[rorix_bw]

I’m just going to through this one out there. What if you put a half decent laser range finder on a jet flying at 30 or 40 thousand feet and flew it over CERN. With a cocktail napkin calculation, I’m guessing you could spot a jet flying over Gran Sasso. Every time you get a reading, both jets photograph the horizon to verify their position. I’m guessing the rangefinder uses light travel time. With that and the distance between the jets verified, you have essentially recreated the experiment using light. Feel free to rip it apart.

All the really cool scientists have underground labs.

Also you'd also need your Sekret Mad Science Gravity Ray to make the plane hover utterly motionless, and then your Orbital Weather Control Laser to stop the wind buffeting it. You could fit that into the GPS satellite that you're not using now that you've got your Range-o-mat plane. Don't forget the army of personally selected, scantily clad (wo)men to operate all the gear. I get first choice of mates after we've taken over the world FOR SCIENCE.

 

[chris2112]

Have tachyons been ruled out as a possibility? If so, why?

Another question that seems important to ask- what are the origin of the neutrinos? Are they produced and given speed by some sort of reaction we create or are they somehow contained and then accelerated?

 

[Drakkith]

Have tachyons been ruled out as a possibility? If so, why?

Another question that seems important to ask- what are the origin of the neutrinos? Are they produced and given speed by some sort of reaction we create or are they somehow contained and then accelerated?

They are accelerated from particle decays where they are created. And I think Tachyons have been ruled out. I actually don't know if they were ever even seriously considered, as it's pretty much guaranteed that these are neutrinos, not tachyons.

 

[PAllen]

Neutrinos as tachyons have at least been considered. The problem is that for tachyons, the more energetic they are, the slower they go - directly from SR equations for tachyons. The OPERA results alone rule this out - they looked for energy dependence and found none that was statistically significant; they should have found a strong energy dependence on speed for tachyons.

Another problem is the supernova results. These neutrinos were much less energetic than OPERA ones, so they should have arrived much faster. Instead, they were light speed to a part in a billion.

Quantitatively, nothing in the OPERA results matches neutrinos are tachyons model.

 

[lalbatros]

That said, I would like to know more about how they are synchronizing the clocks, purely because I can't figure out how to do it!

Maybe you would like to read this:

http://www.bo.infn.it/opera/docs/phd_thesis-BO-2011_05_20-brunetti.pdf

No easy reading.

 

[lalbatros]

Have tachyons been ruled out as a possibility? If so, why?

So many people have been dreaming about the OPERA results that we can be absolutely sure that tachyons were considered. I guess that the OPERA team is too busy with analysing their system and their data too lose more time on speculation than during their cofee break.

 

[Max™]

The SN1987A result is a highly sensitive measurement of the relative speed of light and neutrinos, because it was 168,000 light years away and we were able to detect both from it. Gravity differences are irrelevant because both light and neutrinos saw the same basic gravitational fields during the transition, and are affected in pretty much the same way by gravity. Given the SN1987A result, it is highly unlikely that neutrinos travel faster than light.

I didn't phrase it properly, I meant to say the OPERA neutrinos are traveling across a gravity well.

As the scale of the gravity well from the Earth and the distance of the trip are quite a bit different than those for the SN1987a results, it makes me wonder if neutrinos were to behave differently when passing a gravity well, could that account for the OPERA results?

 

[exponent137]

According to analysis of measurements error, the main problem is with measurements of time (sychronisation) and distance. May they not repeat this measurements with photons somewhere? If they can found enough long distance with similar conditions are CERN -> Gran sasso. .

 

[Prof Niemand]

Even if the OPERA experiment holds up, it perhaps needn't result in an overthrow either of SR or GR. Not an overthrow of SR, because strictly speaking, SR applies only in the absence of a gravitational field. And not an overthrow of GR, because “c” is not the ultimate speed of either light or material objects in GR, when a gravitational field is present.

In GR, the ultimate speed is determined only by the metric tensor. Following Max Born, if for simplicity we imagine a 2-D subset (x,t) of the 4-D spacetime continuum, and assume the off-diagonal elements of the metric tensor vanish, then the light lines are given by:

ds^2 = g11*dx^2 + g44*dt^2 = 0 --> ultimate speed = dx/dt = SQRT(-g44/g11).

In the flat Minkowski spacetime of SR, g11 = 1 & g44 = -c^2, so we have:

ultimate speed = SQRT[-(-c^2)/1] = c, as expected.

But in the curved Riemannian spacetime that exists when a gravitational field is present, the values of g11 & g44 could in principle be any real numbers, thus placing no theoretical upper limit on the ultimate speed in GR.

In the OPERA experiment, where the transit time was 2.4 ms, the discrepancy of 62 ns corresponds to only about 26 PPM. Perhaps this small discrepancy could be explained by a slight deviation of the metric from Minkowski, due the gravitational field of the Earth, along the path through the Earth from Switzerland to Italy. Perhaps using numerical methods, it would be possible to solve the Einstein field equations along this path, to derive the appropriate metric(?)

 

[PAllen]

Even if the OPERA experiment holds up, it perhaps needn't result in an overthrow either of SR or GR. Not an overthrow of SR, because strictly speaking, SR applies only in the absence of a gravitational field. And not an overthrow of GR, because “c” is not the ultimate speed of either light or material objects in GR, when a gravitational field is present.

In GR, the ultimate speed is determined only by the metric tensor. Following Max Born, if for simplicity we imagine a 2-D subset (x,t) of the 4-D spacetime continuum, and assume the off-diagonal elements of the metric tensor vanish, then the light lines are given by:

ds^2 = g11*dx^2 + g44*dt^2 = 0 --> ultimate speed = dx/dt = SQRT(-g44/g11).

In the flat Minkowski spacetime of SR, g11 = 1 & g44 = -c^2, so we have:

ultimate speed = SQRT[-(-c^2)/1] = c, as expected.

But in the curved Riemannian spacetime that exists when a gravitational field is present, the values of g11 & g44 could in principle be any real numbers, thus placing no theoretical upper limit on the ultimate speed in GR.

In the OPERA experiment, where the transit time was 2.4 ms, the discrepancy of 62 ns corresponds to only about 26 PPM. Perhaps this small discrepancy could be explained by a slight deviation of the metric from Minkowski, due the gravitational field of the Earth, along the path through the Earth from Switzerland to Italy. Perhaps using numerical methods, it would be possible to solve the Einstein field equations along this path, to derive the appropriate metric(?)

You posted this in another thread. See my answer there.

Now the CERN measurement is not strictly local, but you can bound that GR impact on measured lightspeed (not coordinate artifacts) is orders of magnitude too small.

 

[Adel Makram]

it perhaps needn't result in an overthrow either of SR or GR. Not an overthrow of SR, because strictly speaking, SR applies only in the absence of a gravitational field.


If the frame of reference of neutrino moves through the gravitational field, it should be regarded as inertial frame of reference according to the equivalence principle. So still SR applied in the neutrino FOR and therefore should violate any superluminal speed :) which was refuted by CERN experiment

 

[silentbob14]

Amazing!

 

[e2m2a]

If we take the altitude of Cern, Switzerland and the altitude of Gran Sasso, Italy, what would be the difference in clock rates between the two locatons due to gravitational time dilation? Has this been factored into the experiment? I believe this is critical and I don't think the difference could be accurately determined.

 

[Drakkith]

If we take the altitude of Cern, Switzerland and the altitude of Gran Sasso, Italy, what would be the difference in clock rates between the two locatons due to gravitational time dilation? Has this been factored into the experiment? I believe this is critical and I don't think the difference could be accurately determined.

I'm about 99% sure that has already been taken into account if it needs to be. And yes, it can be accurately determined.

 

[nitsuj]

And yes, it can be accurately determined [gravitational time dilation].

Do you think the distance can be (was) accurately determined? How far off was the speed from c in distance?

 

[Drakkith]

Do you think the distance can be (was) accurately determined? How far off was the speed from c in distance?

The distance between Cern and Gran Sasso? And what speed? The neutrino's?

 

[Vanadium 50]

Looks like it's that time again.

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.

 

[e2m2a]

Looks like it's that time again.

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.

Thanks for the reference to the paper. My question has been answered in the paper as stated: "The gravitational red-shift due to the different CERN and LNGS altitudes produces an even smaller relative effect of 10-13 on the clocks in between two common-view synchronisations."