Register to reply

CERN team claims measurement of neutrino speed >c

by turbo
Tags: anisotropy, cern, ftl, gps, new math books
Share this thread:
nsaspook
#739
Feb28-12, 10:35 PM
P: 663
Timing delay errors from fiber-optic cable visual.

I built a prototype device to detect bad fiber cables using time delay changes and made a few videos to check pulse delay calibration. These changes in time delays are from only moving the fiber a very small distance from the fully locked position. The display sync is locked on the send pulse on the left, the received (delayed) pulse is on the right.

http://flic.kr/p/bmmGau
Galteeth
#740
Feb29-12, 04:50 AM
P: 320
Quote Quote by nsaspook View Post
Timing delay errors from fiber-optic cable visual.

I built a prototype device to detect bad fiber cables using time delay changes and made a few videos to check pulse delay calibration. These changes in time delays are from only moving the fiber a very small distance from the fully locked position. The display sync is locked on the send pulse on the left, the received (delayed) pulse is on the right.

http://flic.kr/p/bmmGau
http://news.sciencemag.org/sciencein...ne.html?ref=hp
jambaugh
#741
Feb29-12, 05:07 AM
Sci Advisor
PF Gold
jambaugh's Avatar
P: 1,783
Quote Quote by kmarinas86 View Post
I will concede though that, yes, you could say that Lorentz transforms, and not so much the idea of spacetime, is responsible for the notion that FTL travel implies causality violation.
That may be giving up too much. The "idea of space-time" invokes some form of relativity principle which via Lie group deformation and stability arguments leaves either SO(4) (euclidean relativity, we can rotate 360 and travel back in time) ISO(3) (Galilean relativity) or SO(3,1) (Einstein Special Relativity). The implications rule out all but SO(3,1) given a vast amount of observational data and mathematical realities. One might argue that the constant c is incorrect but too much empirically verified evidence depends on the given value.

[For reference see Segal's work on stability of Lie groups under deformation, I have no specific citation but he showed that all semi-simple Lie groups are stable under small perturbations of their algebraic structure (when constrained to still yield a Lie group)]

It all means that Minkowski space-time is on as solid a footing as Euclidean spatial geometry, and these may only be invalidated (without wholly abandoning unified space-time) in the same way, i.e. allowing for curvature in the respective spatial or space-time geometries, i.e. invoking a form of GR.

To abandon locally Lorentzian physics would require abandoning unified space-time all-together and consider some alternative theory with preferred frames and an absolute time... and of course describe a mechanism by which we seem to see Lorentzian physics e.g. Lorentz's original notion that an aether causes slowing of clocks and shrinking of objects.

In short...
In the name of Ockham's razor, I would give up "Lorentzian physics" before I give up causality.
is giving up on "space-time" all together. We would have to go back to the pre-Einstein aether or something similar.

This is why I'd give long odds that any claim to FTL signals is some combination of analytical or experimental error.
jambaugh
#742
Feb29-12, 05:19 AM
Sci Advisor
PF Gold
jambaugh's Avatar
P: 1,783
Quote Quote by kmarinas86 View Post
I think the issue comes from the fact that FTL travel would violate the standard physical interpretation of the mathematics of SR, as opposed to the mathematics of SR in of itself. Thus, the "physics" of relativity would change if FTL travel was discovered, but that doesn't mean that much of the math goes away.
No, you can't "tweak" SR. The "mathematics of SR in and of itself" would have to be abandoned. The mathematics of deformation of the algebra dictates that any variation of the group structure (which defines the value of c) is equivalent to a rescaling of the representation (change in t and x units). This has physical implications e.g. a gravitational field as you vary the group over space-time as in GR. If SR with the current c value is wrong it must be a.) drastically wrong and b.) there must be some additional mechanism making it appear right, and so c.) there's no reason to hold onto any relativity theory or unified space-time except aesthetic preference.
GTOM
#743
Feb29-12, 08:35 AM
P: 119
I think the question is, can something be outside the boundaries of Lorentz transformations, or not?
Otherwise, i can rather accept LET than SR, since we learned, that space actually isnt empty, it is filled with "dark energy" (aether?).
Dickfore
#744
Mar15-12, 05:33 AM
P: 3,014
Quote Quote by Histspec View Post
There is now an official statement by OPERA:
http://www.nature.com/news/flaws-fou...rement-1.10099
And the press release update from February 23:
http://press.web.cern.ch/press/Press.../PR19.11E.html

They say that there were actually two possible sources of error (in opposite directions), which might significantly influence their former result. They will check it in May.
Yes, this press release is one day after the following news article from Science:

BREAKING NEWS: Error Undoes Faster-Than-Light Neutrino Results

dated February 22, 2012
cdux
#745
Mar15-12, 09:50 AM
P: 190
In layman's terms is the neutrino faster than light buried by the consensus?
yuiop
#746
Mar15-12, 10:40 AM
P: 3,967
Quote Quote by cdux View Post
In layman's terms is the neutrino faster than light buried by the consensus?
Think so.
Enoy
#747
Mar16-12, 09:17 AM
P: 6
ICARUS posted yesterday a paper where they show that neutrinos from cern to ICARUS was exactly at the light speed 299792,458 km/s :-(

http://arxiv.org/abs/1203.3433

If similar experiments, at OPERA and Fermilab later this year, finds the same result, that V-C = 0, it means that neutrinos that moves through the earth can not move faster than light inside earth (mass-densities). And in my opinion this means that aether-theory actually is finally falsified in an absolute way ! The reason for why I mean this, is that if there is an aether that light spreads through, this aether should have been "more thin / thinner" inside mass densities like the earth, and then massless particles / light-photons would have spread faster through this thinner aether inside earth ! But now that (if) it is not true that speed limit is higher inside earth, this means that an aether can NOT be real !!!!
Ryan_m_b
#748
Mar16-12, 10:13 AM
Mentor
Ryan_m_b's Avatar
P: 5,490
BBC reports slow neutrinos - http://www.bbc.co.uk/news/science-environment-17364682
Dickfore
#749
Mar16-12, 10:52 AM
P: 3,014
Is someone still moderating this thread? I would appreciate if the mention of aether is purged out of this thread.
PhilDSP
#750
Mar16-12, 10:53 AM
P: 612
Isn't the fact that a massive particle has been measured to travel at c slightly upsetting in itself?
Dickfore
#751
Mar16-12, 11:03 AM
P: 3,014
It is. However, [itex](c - v)/c \equiv \epsilon \sim 10^{-5}[/itex] is compatible with SR and the experimental uncertainty of all these experiments.

The energy of a particle travelling at this close speed to c is:
[tex]
\begin{array}{l}
\frac{E}{m \, c^2} = \gamma = \left ( 1 - \frac{v^2}{c^2} \right)^{-\frac{1}{2}} \\

= \left[ 1 - (1 - \epsilon)^2 \right]^{-\frac{1}{2}} \\

= \left[ 2 \epsilon \, \left( 1 - \frac{\epsilon}{2}\right) \right]^{-\frac{1}{2}} \\

\sim (2 \epsilon)^{-\frac{1}{2}} \, \left[1 + \frac{\epsilon}{4} + O(\epsilon^2) \right]
\end{array}
[/tex]
Considering the rest energy of neutrinos is of the order of 0.1 eV, this means that the energy of these neutrinos would be of the order of:
[tex]
\frac{0.1 \, \mathrm{eV}}{\sqrt{2 \times 10^{-5}}} \sim 20 eV
[/tex]
which is negligible. Even higher energies would bring the speed of neutrinos so close to c that the difference could not be detectable in any terrestrial experiment.
gvk
#752
Mar16-12, 12:05 PM
P: 83
All right. Thank you, ICARUS.
StevieTNZ
#753
Mar16-12, 12:56 PM
PF Gold
StevieTNZ's Avatar
P: 821
This is in the news: http://www.physorg.com/news/2012-03-...oss-check.html
TrickyDicky
#754
Mar16-12, 02:40 PM
P: 3,060
ICARUS used a new measuring detector based on liquid argon time projection chambers, anybody knows why this way of measuring speed of neutrinos is better or more reliable than the one used by OPERA? or how this change in mesuring technique might affect the results?
PAllen
#755
Mar16-12, 02:43 PM
Sci Advisor
PF Gold
P: 5,087
Quote Quote by TrickyDicky View Post
ICARUS used a new measuring detector based on liquid argon time projection chambers, anybody knows why this way of measuring speed of neutrinos is better or more reliable than the one used by OPERA? or how this change in mesuring technique might affect the results?
I assume the detector is irrelevant. Just a different group, re-doing the goedesy and timing independently; different time delays for cables etc.
exponent137
#756
Mar17-12, 01:40 AM
P: 295
Mistake of measurement (4 and 9) was very large according to dissagreement (0.3).
δt = (0.3 4.0stat 9.0syst)ns
Does this mean that both mistakes (stat and syst) are really much smaller if they would be more precisely determined?


Register to reply

Related Discussions
CERN, speed of light... Special & General Relativity 6
Does neutrino oscillation from electron neutrino to muon neutrino conserve energy? High Energy, Nuclear, Particle Physics 4
Avg Speed of Relay team (x and t are not given) Introductory Physics Homework 1