Well, this could change things (neutrinos)

[Game_boy]

EDIT: Oh, also my A-level physics taught me that the speed of light is not the limit for the rate of expansion of space. Is this entirely untrue, or could it have some sort of effect if it is?

If no information is transmitted by the expansion it can go at any speed.

[Aiwendil]

Strictly speaking, the rate of expansion of the universe doesn't have units of speed; it has units of inverse time. The speed at which two objects are moving away from each other due to the expansion of the universe is given by the expansion rate times the distance between them. So, for any rate of expansion, you can have two objects moving away from each other faster than the speed of light, by choosing two objects that are sufficiently far apart. But, as Game_boy said, no information is transmitted, and special relativity is not violated.

[thoughtfully]

Also, CERN and the detector are almost zero distance from each other, cosmologically speaking. The expansion of space is utterly negligible at these scales. Good thing too, I like the planet I live on to hold together. Of course, if the rate of expansion continues accelerating, this could be our eventual fate.

[dockaon]

Ahh, I didn't realize that this experiment was using two different kinds of detectors, one kind at CERN (a Beam Current Transformer, something like this) and a different kind at LNGS in Italy, using bricks of photographic emulsion films (picture here). I was assuming that at least one of the two, and possibily both were like the water/phototube detector used at the Super-Kamiokande Detector in Japan or SNO. But I guess that the size of these "older" detectors wouldn't allow for the necessary measurement accuracy, at least in terms of timing? I'd think that they would be at least as good at detecting individual neutrino interactions, if not better?

I think it may be optimization for different energy ranges. Super-Kamiokande and SNO are both sensitive to solar and reactor neutrinos in the MeV energy range while the OPERA neutrinos are in the 10 - 30 GeV energy range. This substantially changes the characteristics of the interaction.

Also it could be a cost issue, the ginormous photo-multiplier tubes that Super-K and SNO use aren't cheap and they're fragile (Super-K had an incident where one shattered and the resulting shockwave took out around half the other tubes.) So it may be that Super-K and SNO are trading greater expense for greater efficiency which is necessary when you're looking at solar neutrinos or proton decay (which were the original goals of the SNO and Super-K detectors), but not when you have a high intensity beam of neutrinos pointed at you.

[Nat]

I think I heard time travel could be theoretically possible, and is equivalent under relativity to superluminal velocities (sorry about the wording, it's just really fun to say/write that). Couldn't that explain this?

[gmalivuk]

A lot of the aesthetic part of wanting Relativity to remain intact is discomfort with the violations of causality entailed by FTL travel (which, as you say, would allow for time travel).

[Tass]

I think I heard time travel could be theoretically possible, and is equivalent under relativity to superluminal velocities (sorry about the wording, it's just really fun to say/write that). Couldn't that explain this?

It has been explained multiple times. Read this thread and the sticky relativity thread. Then ask if you still have questions.

But the short answer is, of course, yes. Superluminal velocities is equivalent to timetravel because of the relativity of simultaneity.

[JWalker]

A lot of the aesthetic part of wanting Relativity to remain intact is discomfort with the violations of causality entailed by FTL travel (which, as you say, would allow for time travel).

If relativity is violated, FTL travel may not imply causality violations, since it is relativity that tells us that FTL travel causes violations of causality. This discomfort is more or less circular.

[Robert'); DROP TABLE *;]

Relativity has been validated by far more experimental evidence, however.

[[Kreativername]]

New paper out with an explanation for an early arrival time of about 64 ns.

http://arxiv.org/abs/1110.2685

The Michelson-Morley experiment shows that the experimental outcome of an interference experiment does not depend on the constant velocity of the setup with respect to an inertial frame of reference. From this one can conclude the existence of an invariant velocity of light. However it does not follow from their experiment that a time-of-flight is reference frame independent. In fact the theory of special relativity predicts that the distance between the production location of a particle and the detection location will be changed in all reference frames which have a velocity component parallel to the baseline separating source and detector in a foton time-of-flight experiment. For the OPERA experiment we find that
the associated correction is in the order of 32 ns. Because, judging from the information provided, the correction needs to be applied twice in the OPERA experiment the total correction to the final results is in the order of 64 ns. Thus bringing the apparent velocities of neutrino’s back to a value not significantly different from the speed of light. We end this short letter by suggesting an analysis of the experimental data which would illustrate the effects described.

[curtis95112]

If this stands up to scrutiny, does this mean that the 'discrepancy' was actually predicted by SR but was so subtle nobody noticed it before this?

[BlackSails]

If this stands up to scrutiny, does this mean that the 'discrepancy' was actually predicted by SR but was so subtle nobody noticed it before this?

Yes, and that means it goes from "LOLOLOL RELATIVITY IS WRONG" to "oh look, another experiment whose results are explained by relativity"

[Twistar]

eesh, that sounds pretty embarrassing. A lot of people here mentioned checking the GPS and relativity..

[PM 2Ring]

Um, the stuff in [Kreativername]'s post isn't subtle - it's fairly basic Special Relativity. Most people around the world who've been discussing this experiment & understand the basics of relativity have assumed that the OPERA people have taken these kinds of things into account in their calculations. So if this explanation is the actual reason for the anomaly, the people involved in the OPERA experiment will be more than a little red-faced.

[ninja'd by Twistar]

[Macbi]

Best abstract ever.

[PM 2Ring]

Roffle.

[doogly]

Berry is a boss. (his collaborators are probably also cool)

[dainbramage]

That's funny, yet it also reminds me of this: http://www.smbc-comics.com/index.php?db=comics&id=2075

[JudeMorrigan]

A lot of the aesthetic part of wanting Relativity to remain intact is discomfort with the violations of causality entailed by FTL travel (which, as you say, would allow for time travel).

If relativity is violated, FTL travel may not imply causality violations, since it is relativity that tells us that FTL travel causes violations of causality. This discomfort is more or less circular.

Yup. Relativity, superluminal velocities and causality; choose two of three.

[gorcee]

New paper out with an explanation for an early arrival time of about 64 ns.

http://arxiv.org/abs/1110.2685

The Michelson-Morley experiment shows that the experimental outcome of an interference experiment does not depend on the constant velocity of the setup with respect to an inertial frame of reference. From this one can conclude the existence of an invariant velocity of light. However it does not follow from their experiment that a time-of-flight is reference frame independent. In fact the theory of special relativity predicts that the distance between the production location of a particle and the detection location will be changed in all reference frames which have a velocity component parallel to the baseline separating source and detector in a foton time-of-flight experiment. For the OPERA experiment we find that
the associated correction is in the order of 32 ns. Because, judging from the information provided, the correction needs to be applied twice in the OPERA experiment the total correction to the final results is in the order of 64 ns. Thus bringing the apparent velocities of neutrino’s back to a value not significantly different from the speed of light. We end this short letter by suggesting an analysis of the experimental data which would illustrate the effects described.

I seriously question the logic in computing the possible error at 32 ns, and then multiplying by two. The article also doesn't seem to consider the effect of multiple satellites on the measurement of the signal.

[lorb]

New paper out with an explanation for an early arrival time of about 64 ns.

http://arxiv.org/abs/1110.2685

The Michelson-Morley experiment shows that the experimental outcome of an interference experiment does not depend on the constant velocity of the setup with respect to an inertial frame of reference. From this one can conclude the existence of an invariant velocity of light. However it does not follow from their experiment that a time-of-flight is reference frame independent. In fact the theory of special relativity predicts that the distance between the production location of a particle and the detection location will be changed in all reference frames which have a velocity component parallel to the baseline separating source and detector in a foton time-of-flight experiment. For the OPERA experiment we find that
the associated correction is in the order of 32 ns. Because, judging from the information provided, the correction needs to be applied twice in the OPERA experiment the total correction to the final results is in the order of 64 ns. Thus bringing the apparent velocities of neutrino’s back to a value not significantly different from the speed of light. We end this short letter by suggesting an analysis of the experimental data which would illustrate the effects described.

Why is he doing classic ("not-relativistic") addition of velocities in equation (2) in the paper?
Why does this not apply here?

[Yakk]

Because from the perspective of the satellite, two things moving at c towards each other actually approach each other at 2c.

Similarly, two things that the satellite thinks are moving at 1/2 c that are approaching each other seem to close the distance at a speed of c.

Using relativistic addition doesn't give this result.

[gorcee]

Because from the perspective of the satellite, two things moving at c towards each other actually approach each other at 2c.

Similarly, two things that the satellite thinks are moving at 1/2 c that are approaching each other seem to close the distance at a speed of c.

Using relativistic addition doesn't give this result.

Wait... huh?

[Yakk]

I am standing here.

A long way away in front of me, I see two fast-moving cars heading towards each other, perpendicular to me. (far enough away that they are basically moving at right angles to me).

Each seem to be moving at 1/2 c. They are heading directly towards each other. One is 5 light seconds left of "strait ahead", and the other is 5 light seconds right. So they appear to be 10 light seconds apart.

How many seconds from this moment to I see them collide?

Answer: 10 light seconds / (1/2 c + 1/2 c) = 10 seconds from now.

No relativistic addition required.

[gorcee]

I am standing here.

A long way away in front of me, I see two fast-moving cars heading towards each other, perpendicular to me. (far enough away that they are basically moving at right angles to me).

Each seem to be moving at 1/2 c. They are heading directly towards each other. One is 5 light seconds left of "strait ahead", and the other is 5 light seconds right. So they appear to be 10 light seconds apart.

How many seconds from this moment to I see them collide?

Answer: 10 light seconds / (1/2 c + 1/2 c) = 10 seconds from now.

No relativistic addition required.

Ah, I was confused by how you said "actually approach each other".

[jaap]

Relativistic addition of velocities is only for adding velocities from different reference frames. In this case, both velocities are already specified in your own reference frame (or the satellite's), i.e. they are the velocities at which the two objects move relative to you/the satellite.

[david.a.symons]

Hi,

The way I see it this is the first truly accurate measurement of the speed of Neutrinos. The only other earthbound measurement made (at the MINOS facility in the US) also made the exact same discovery however wasn't precise enough to confirm the results.
All other previous measurements of the speed of neutrinos have been taken from observing cosmic events such as super novae or measuring the time they take to get from the sun to earth etc.
The problem I have with any of these previous measurements is that the only way we calculate the distance to these events (to then calculate the speed of the particles we detect) is by relying on the speed of light being a constant. So in doing so any measurements we get for the distance then resulting speed could be totally false according to the new OPERA results.
This is why I have a lot of faith in the Italian results as they are using a simple, easy (also once continental shift is accounted for...yes they actually accounted for the slight movements in the earths crust which could extend the distance between Italy and Switzerland!!) and physically measurable distance (not relying on the speed of light as a tool) making what I consider a perfectly viable measure for the speed of Neutrinos.
So maybe we should start rethinking of physics a little bit. But I don't think that's a bad thing at all.

Thanks,
Dave

Combined your Two Posts into One Post. You'll thank me when you're older. ~~Felstaff

Another post about the whole sending messages back in time thing.

Do you realize the ridiculous circumstances we would have to create to allow that to happen? First the receiver would have to be moving relative to the sender at speed getting very close to the speed of light (engineer guy if you know of any kind of vehicle that can do that, please let me know) and secondly the message would then have to be transferred not by the conventional electromagnetic waves that a cell phone uses but it would have to somehow transmit neutrinos, which would then be detected and converted to text by the receiving phone?

Seriously?

Not gonna happen.

What might happen is we get slightly closer to understanding how the universe really works and getting closer to a unified theory of Quantum theory and General Relativity. I don't see any practical applications for a loooooooooooooooooooooooooooooooooooooooooooong time.

Thanks again,
Dave

[Malconstant]

@ Dave,

Hey there! If you'd like to know what's been covered so far on this thread, please indulge in the preceding 7 pages of discussion on this topic.

Some counter thoughts which have been mentioned already:

-SN1987A, in which neutrinos were determined to be traveling slightly slower than light in vacuum.
-LHC, in which the speed of light in vacuum, as well as its functional role as the absolute speed limit of the universe through SR, has been verified to many orders of magnitude greater precision than the OPERA experiment.

You could be right, in fact I've got $5 I'm betting against $50 of Doogly's that the results will be verified within a year and we'll have to consider another reason why neutrinos are unthinkably weird. (I don't actually think I'm right in my bet though, I just like the 10 to 1 pay off). And at this point, other than experimental error, the most likely candidate is a worm hole inside the Earth. Just to give that some perspective.

Edit:
As for the backwards in time thing, the worry isn't so much for practical concerns as ontological ones. You don't have to actually build a time machine, if you can just tell me that you have proof that it would be theoretically possible to build a time machine under certain circumstances, that'd be enough to radically re-frame the way in which we view the world. I mean, you can just go by Newton's laws and balk at GR corrections as totally unnecessary for day to day life, and you'd be right, but also very silly to ignore the ontological significance of the theory.

[gmalivuk]

In fact the theory of special relativity predicts that the distance between the production location of a particle and the detection location will be changed in all reference frames which have a velocity component parallel to the baseline separating source and detector

Yes, but unless the time is also stupidly being measured in this moving reference frame, instead of the much more sensible reference frame of the detector itself, this is irrelevant.

[JWalker]

Bumping with these articles about some new results:

http://www.science20.com/quantum_diarie ... ight-84763

http://www.interactions.org/cms/?pid=1031226

And the pre-print for those so inclined:

http://arxiv.org/abs/1109.4897v2

[Qaanol]

Bumping with these articles about some new results:

http://www.science20.com/quantum_diarie ... ight-84763

http://www.interactions.org/cms/?pid=1031226

And the pre-print for those so inclined:

http://arxiv.org/abs/1109.4897v2

Summed up: New experiments shooting individual neutrinos show the same ≈60ns early arrival, now with greater precision. Also, about ±20ns spread in arrival time. I think we should drill a hole from CERN to LNGS and shoot lasers down it to measure how long light actually takes to get there.

Comments on the first of your links suggest alternate explanations. One in particular proffers the notion that the neutrinos might be traveling at standard subluminal speeds, a high fraction of c, but they start the trip by “jumping” out 18m or so. There are a variety of suggestions as to how that initial “teleport” could take place. The progenitor of that explanation further states that it is still far more likely that there is some systematic error in the measurements. One way to test that hypothesis would be to make another detector at a different distance from CERN than LNGS is, to see if the time in advance that neutrinos arrive is a flat 60ns or if it scales with distance.

[mfb]

Summed up: New experiments shooting individual neutrinos show the same ≈60ns early arrival, now with greater precision. Also, about ±20ns spread in arrival time. I think we should drill a hole from CERN to LNGS and shoot lasers down it to measure how long light actually takes to get there.

Well, shooting single neutrinos at a time would give negligible probabilities to detect any neutrino at all. But they used pulses of only 3ns length, so each detected neutrino can be used as indiviual measurement (instead of 15.000 for a single fit as before).

So the pulse-shape stuff is gone, length and timing remain.

[Darrell88]

Hmmm I have a noob question: How do they measure the time of departure and time of arrival of these neutrinos ???

[need4speed]

I see interesting applications in middle-school dodge-ball competitions.

If only I wouldn't always be the last one picked. . .

[ibgdude]

Departure:
"The kicker magnet trigger-signal for the proton extraction from the SPS is UTC (Coordinated Universal Time) time-stamped with a Symmetricom Xli GPS receiver [10]. The schematic of the SPS/CNGS timing system is shown in Fig. 3. The determination of the delays shown in Fig. 3 is described in section 6. The proton beam time-structure is accurately measured by a fast Beam Current Transformer (BCT) detector [11] (BFCTI400344) located (743.391 ± 0.002) m upstream of the centre of the graphite target and read out by a 1 GS/s Wave Form Digitiser (WFD) Acqiris DP110 with a 250 MHz bandwidth [12]. The BCT consists of toroidal transformers coaxial to the proton beam providing a signal proportional to the beam current transiting through it, with a 400 MHz bandwidth. The linearity of the device is better than 1% and it is operated far from the saturation limit. The start of the digitisation window of the WFD is triggered by the kicker magnet signal. The waveforms recorded for each extraction by the WFD are stamped with the UTC and stored in the CNGS database"

In other words, they know when they pull the protons out of the accelerator, and they also measure the proton's passage just before they hit the target to create the neutrinos, so they know the time of departure.

Arrival:
"The OPERA neutrino detector at LNGS is composed of two identical Super Modules, each consisting of an instrumented target section with a mass of about 625 tons followed by a magnetic muon spectrometer. Each section is a succession of walls filled with emulsion film/lead units interleaved with pairs of 6.7 × 6.7 m^2 planes of 256 horizontal and vertical scintillator strips composing the Target Tracker (TT). The TT allows the location of neutrino interactions in the target. This detector is also used to measure the arrival time of neutrinos. The scintillating strips are read out on both sides through WLS Kuraray Y11 fibres coupled to 64-channel Hamamatsu H7546 photomultipliers [8]. Extensive information on the OPERA experiment is given in [1] and in particular for the TT in [9]"

In other words, they watch for the neutrinos whacking into the lead sheets using emulsion film, fibre optics and photo multipliers.

[Macbi]

Bumping with these articles about some new results:

http://www.science20.com/quantum_diarie ... ight-84763

http://www.interactions.org/cms/?pid=1031226

And the pre-print for those so inclined:

http://arxiv.org/abs/1109.4897v2

From the first link:

It is necessary here to note that since distance from source to detector and time offsets necessary to determine the travel time of neutrinos have not been remeasured, the related systematics (estimated as well as -possibly- underestimated ones) are unchanged. The measurement therefore is only a "partial" confirmation of the earlier result: it is consistent with it, but could be just as wrong as the other.

[WarDaft]

On a not particularly sciencey note, anyone else reminded of Fine Structure (the story) where there's a tiny seemingly inexplicable hiccough in the results from a particle accelerator test, which then leads to an entirely new understanding of science, which is then cancelled because the universe doesn't want them playing around with that stuff?

[Yakk]

Which part of Fine Structure? It is a multi-part story.

[WarDaft]

The whole discovering of FTL communication and (subsequently) teleportation that basically kicks off the eka script technology arms race. Or at least, that's how the story was when I read it, it was still significantly a work in progress at that time.

[Eternal Questionner]

We've heard several times that relativity still holds with this results, we just lose causality. But tell me, if this result is true, how exactly would we go about sending information from the future to the past using neutrinos? Could this be attempted with current technology?