Neutrinos break speed of light

[TriPolar]

@davidm

Suppose, for the sake of discussion, that this holds up. Can we then transmit information into the past?

I think so. I saw this thread, then used neutrinos to start one 7 minutes in the past in GQ.

[Pasta]

TriPolar’s GQ thread.

[carnivorousplant]

@drewtwo99

I took a physics class about the nature of time, and I remember the professor talking about how if you had an object traveling faster than c,

When I took physics, a mere three semesters, the instructors refused to entertain questions beginning with “An object raveling faster than light.”

[Nissim_Levy]

I have two reasons to feel confident that the results showing Neutrinos travelling faster than light are faulty:
reason 1

The equation E = MC squared has the speed of light as a term and if there was a faster speed than light in the universe then this equation would be wrong because it would need to use that faster speed instead of light speed. This is because the relevant speed is the fastest speed at which information can be transferred. So if these researchers are correct about neutrinos being slighly faster than light then the equation E = MC squared would be slightly wrong also. Actually it will be easier to detect a discrepancy with this equation because light speed gets squared and therefore any increase over the speed of light is amplified. So why haven’t scientists ever discovered a problem with this equation?

reason 2

Thee is no denying that light speed is absolute in all frames of reference. This kind of exhalted quality leads me to strongly suspect that there is something special about the speed of light.

[Nissim_Levy]

Will Einstein be considered wrong and physics as we know it be over?

[Starving_Artist]

@Gyrate

And what if the neutrino is carrying a flashlight and then turns it on?

Or what if the neutrino is carrying a Fleshlight and it turns the neutrino on?

[TriPolar]

There’s another option maybe. It could be another spooky thing where neutrinos seem to move faster than light, but you can’t use them to transmit information, or flat out weird where neutrinos are always measured to exceed the speed of light, but never do. I have no idea, but physics seems to answer one riddle with two more sometimes.

[Ken001]

In the Theory of Special Relativity Albert Einstein did not say nothing could travel faster than the speed of light. Rather, he said that information cannot travel faster than C.

We already know about quantum entanglement which appears to confound Special Relativity, but so far we have no idea of how it works.

E=mc2 still holds but maybe, just maybe there are exceptions. Exciting stuff.

[Ken001]

There are plenty of known examples in physics of actions exceeding the speed of light. A simple example is the Earth’s shadow passing across another object at an extreme distance. That would exceed C. We could observe it but we couldn’t know anything more about it.

The tricky neutrinos may be moving to another part of space/time for an instant, or even another universe. The question is Why? How? Extra cool.

[Naxos]

@Ken001

There are plenty of known examples in physics of actions exceeding the speed of light. …

Superstition is not the same as physics.

[Capt.Ridley_s_Shooting_Party]

The data is here. Here’s an interesting post from a high-energy physicist in a discussion of this paper on Reddit:

According to the paper, the chance that this is statistical or systematic error is less than 1 in a billion. (This is a 6.0 sigma measurement.)

Having just finished reading the paper, I have to admit it’s an impressive measurement. They’ve carefully examined every source of systematic error they could imagine (see Table 2), and included enough events (about 16,000 events, or 1020 protons) to bring statistical error down to the range of systematic error. Their calibrations were performed in a blind way – so that they could remove any bias from this process – and, according to the paper, the unblinded result fit quite nicely with expectation, without any further tinkering necessary (see Figure 11). I’d also commend them for being dutiful experimentalists, and not wasting their breath speculating on the phenomenological or theoretical implications of this result. They know the result will raise eyebrows, and they don’t need to oversell it with talk about time-traveling tachyons and whatnot.

The authors are also upfront about previous experimental results that contradict their own. Specifically, an observation of lower energy neutrinos from the 1987A supernova found an upper-limit to neutrino velocity much closer to the speed of light. (In this new paper, they go so far as to break up events into high-energy and low-energy neutrinos, to see whether maybe there is an energy dependence for their observed result. They do not find any such energy dependence. See Figure 13.)

This measurement does not rely on timing the travel of individual particles, but on the probability density function of a distribution of events. Therefore, it’s critical that they understand the timing of the extraction of the protons, which will arrive at the graphite target with a bunch structure (see Figure 4), as it is the timing of the arrival of these bunches at the target (and the resulting blast of neutrinos it will receive in response) that will be detected at LNGS.

By far, their largest source of systematic error in timing is an uncertainty in the amount of delay from when the protons cross the Beam Current Transformer (BCT) detector to the time a signal arrives to the Wave Form Digitizer (WFD). This delay is entirely within measurements upstream of the target. The BCT detector is a set of coaxial transformers built around the proton beamline in the proton synchrotron, detecting the passage of the protons before they are extracted for this experiment. The WFD is triggered not by the passage of the protons, but by the kicker magnets which perform the extraction of those protons. To tamp down some of the uncertainty in the internal timing of the BCT, the researchers used the very clean environment of injecting protons from the CERN Super Proton Synchrotron (SPS) into the LHC while monitoring the performance of the BCT. All that said, I don’t have the expertise to identify any issues with their final assignment of 5.0 ns systematic uncertainty for this effect.

I won’t delve into each of the other systematic errors in Table 2, but I can try to answer what questions you might have.

If I were eager to debunk this paper, I would work very hard to propose systematic errors that the authors have not considered, in the hopes that I might come up with a significant oversight on their part. However (perhaps due to a lack of imagination), I can’t think of anything they haven’t properly studied.

The simplest answer (and scientists so often prefer simplicity when it can be achieved) is that they’ve overlooked something. That said, it is my experience that collaborations are reluctant to publish a paper like this without a thorough internal vetting. They almost certainly had every expert on their experiment firing off questions at their meetings, looking for chinks in the armor.

It will be interesting to see how this holds up.

[Rysdad]

@lalenin

I will be the first to blame steroids.

No, Bush.

[Half_Man_Half_Wit]

To my mind, there are several possible ways of interpreting this result:

[ol]
[li]Experimental error[/li][li]Neutrinos travel faster than c[/li][li]Neutrinos travel faster than light[/li][li]Something unknown is doing we don’t know what[/li][/ol]

Option 1 is the most likely, though having seen the OPERA collab’s talk at CERN yesterday and read through the paper (cursorily, at least), they have done an exceptional job at trying to precisely quantify every conceivable source of error (as one should expect for a result this surprising). Also, one should take note that what they’re basically doing is not announcing ‘neutrinos travel faster than the speed of light’, as unfortunately many popular outlets do, but ‘here’s what we measured, we refrain from further interpretation’ – basically, it’s an invitation to the scientific community to try and make sense of these results.

Option 2 is the most exciting, Earth-shattering scientific discovery wise. Here, c is meant to signify the invariant speed limit set by special relativity – meaning the speed at which a massless particle propagates through empty space. I can think of two ways this could work: first, neutrinos could be tachyons. Tachyons are hypothetical particles that always travel faster than c, allowed in the sense that they’re not excluded by special relativity, that are commonly thought to be bad news in a lot of contexts, such as quantum field theories. Such particles have the paradoxical property that the less energy they have, the faster they go. This means that this explanation is basically excluded by the observation of neutrinos from the 1987A supernova, where we observed neutrinos at much lower energy than those observed by OPERA that nevertheless can’t have travelled (much) faster than c, and were definitely slower than what OPERA sees.

The other possibility would be neutrinos taking some kind of shortcut, for instance propagating through the so-called bulk, a higher dimensional space in which our spacetime is embedded, in what’s known as a braneworld scenario. I can’t really say much about this, but again it seems strange here that the neutrinos from the 1987A supernova apparently couldn’t find such a shortcut.

Option 3 is possible because ‘speed of light’ does not necessarily mean ‘c’. It could be the case that photons travel very slightly slower than the fastest possible speed, and that neutrinos therefore travel faster than photons, but still slower than c (or maximally at c). One possibility would be that photons aren’t massless, as is commonly believed, but do have a very small rest mass. There are, however, problems with this proposal: for one, it would mean that photons at different energies travel at different speeds, on which there are very tight experimental constraints.

Another, to me more intriguing, possibility would be that due to quantum effects, the vacuum might have a small refraction index, meaning that light would not move exactly at c, but slightly slower, despite not having a rest mass – basically, a photon might spontaneously produce an electron/positron pair, which annihilates after a short time back to a photon; the electron and the positron, being massive particles, can’t move at c, so the overall propagation of the photon is slowed even in vacuum. This is known as the Scharnhorst effect, which is so far purely theoretical. I’ve done a quick and dirty calculation (cf. this post in the GQ thread), and the effect comes out as just a bit too small to account for the observed discrepancy; however, the approximation I made really doesn’t cover the relevant case, so one should expect the actual effect to be somewhat greater. In this case, one would also expect that lower energy neutrinos travel at lesser speeds, so this could potentially be consistent with the supernova observations.

About option 4, of course, I can’t really say much, other than that it’s difficult to even imagine contexts in which this result would fit, and not violently clash with other, much better established results.

[Balance]

@Half_Man_Half_Wit

The other possibility would be neutrinos taking some kind of shortcut, for instance propagating through the so-called bulk, a higher dimensional space in which our spacetime is embedded, in what’s known as a braneworld scenario. I can’t really say much about this, but again it seems strange here that the neutrinos from the 1987A supernova apparently couldn’t find such a shortcut.

As long as we’re engaging in premature speculation…what if the incidence of tunneling is proportional to the density of matter in the primary medium? Or to the local intensity of gravity? That is, what if neutrinos are more likely to find shortcuts when passing through dense matter or in more intense gravity than in deep space? Suppose, for example, that a tunneling event could be triggered by a neutrino impinging on a more massive particle in a certain way; the probability of such events would obviously be higher for a cluster of neutrinos passing through rock than through a vacuum, or even through gas clouds.

(What can I say, I enjoy speculating about things I don’t know enough about.)

[Half_Man_Half_Wit]

@Balance

As long as we’re engaging in premature speculation…what if the incidence of tunneling is proportional to the density of matter in the primary medium? Or to the local intensity of gravity? That is, what if neutrinos are more likely to find shortcuts when passing through dense matter or in more intense gravity than in deep space? Suppose, for example, that a tunneling event could be triggered by a neutrino impinging on a more massive particle in a certain way; the probability of such events would obviously be higher for a cluster of neutrinos passing through rock than through a vacuum, or even through gas clouds.

(What can I say, I enjoy speculating about things I don’t know enough about.)

This doesn’t really have anything to do with quantum mechanical tunneling, and as for the density of matter, to a neutrino, a couple of hundred kilometers of rock isn’t really much denser than empty space. The braneworld scenario presumes that we live on a 4 dimensional ‘brane’, embedded in a higher dimensional ‘bulk’. Certain particles can leave the brane and travel through the bulk; I don’t know of any way that capacity could vary wrt ambient matter density/gravitational field, so your idea would fall under the ‘something unknown is doing we don’t know what’ heading, I think…

[Balance]

@Half_Man_Half_Wit

…so your idea would fall under the ‘something unknown is doing we don’t know what’ heading, I think…

Well, that was sort of the point.

Oh, and by “tunneling”, I was referring to your postulated “shortcuts” rather than quantum tunneling. “Shortcutting” struck me as unwieldy.

[foolsguinea]

Isn’t it more likely that the measurement of the maximum speed of light is off slightly, and neutrinos are just bypassing something that slows light in the local context?

Or that the neutrinos are taking a straighter path than we knew there was and getting there more quickly?

[Gyrate]

@Starving_Artist

Or what if the neutrino is carrying a Fleshlight and it turns the neutrino on?

That’s a whole new meaning for “premature ejaculation”.

[Boyo_Jim]

Does anyone know which direction the wind was blowing?

And what the fine is for traveling 187,000 miles per second in a 186,000 miles per second speed zone?

[billfish678]

@Boyo_Jim

Does anyone know which direction the wind was blowing?

And what the fine is for traveling 187,000 miles per second in a 186,000 miles per second speed zone?

Doesn’t matter. Crown Vics don’t go that fast. And the ticket camera sure won’t work.