It seems like this new result have some of the same problems as the first, no? From the article linked:


Is there any reason why we can't test the speed of the neutrinos directly compared to light? I.e. send a neutrino particle and a photon and see who gets to the detector first.

my understanding is that neutrinos travel through stuff unaffected, whereas light does not.

this experiment is done through the ground, whereas the light tests are done in the circular tubes at cern?

i don't really know. i think the main issue is an exact measurement of the distance travelled for this experiment.

The problem is that neutrino detectors have to be underground otherwise they are hella noisy. It is very, very difficult to survey the location of the underground neutrino detector at Gran Sasso with great precision. They say they're good to 20 cm IIRC, but I think that might be optimistic.

Thus, at the end of the day, setting up a light vs neutrino horse race would be a tuffy.

Hi masque...your point is well-taken. My point is that the reported explanation assumed that no relativity correction was made by GPS, and that is wrong. You are quite right that the assumption about how good the clock solution on the ground is might be off. In fact, my $$ says that's where the error lies.

I think this was mentioned ITT previously, but there have been horse races...when there are supernovae, copious amounts of everything (including neutrinos and photons) are produced. IIRC, we usually detect about 10 neutrinos per experiment (Super Kamiokande, the Gran Sasso experiment, and maybe the one in northern Minnesota--outside Soudan) and obviously plenty of photons. Those detections show virtually dead heats, and those races are over many light-years.

That said, one thing that immediately springs to mind is that the above race is through interstellar media. The Gran Sasso race is through the earth. If there's something going on--interactions that we're not aware of, some effect of gravity we don't know about, etc...--the "track" could affect the race. We don't know of any effect now, but it could exist.

As an illustration, the 'speed of light' through a wire--actually the speed of propagation of a signal, which is an electro-magnetic wave--is about 1/3 c.

What they did further eliminates a few issues for sure and its great. But its not over yet by far since 90% of the experiment is still the same.


What they need to do further is produce very low energy neutrinos under the same setup they have and establish the result then. In preference i would love to see them try only a few Mev type neutrinos (500-300 times less than current energy) . It should be easy to produce and the only issue is if the probability of detection rapidly changes at G.Sasso to make this not practical within days and requires instead years of collection. (how the detection reaction probability ie cross section is affected by the neutrino energy, need to look this up to see if its a problem)

If they can establish a lack of variation with the energy it would further enhance the chance this is systematic error.

On the other hand if they can establish that supernova type energy neutrinos have the same result it would conflict supernova observations unless the effect is simply a starting effect (they gain time at start only superluminal only at the very first part of their creation and emission although its hard to explain why that would be the case, and the rest of the path is at speed c). Now of course the important detail here is that the beam here is made of muon neutrinos, not electron neutrinos and there may be a minimum their energy can be given typical creation processes that is far higher than the supernova ones (energy of few Mev). GS is detecting muon neutrinos and tau neutrinos. Not sure if it can detect also electron neutrinos under same setup or its very different. Maybe some experimental particle physicist can comment if reading about how plausible a very small energy beam of muon neutrinos is in this experiment. If the effect shows a strong correlation with energy it would be very telling and we need somehow to produce something that can be related to the supernova cases where excess speed over light was not found in order to produce a conflict.


The other thing is to try a distance in other labs that is very different and exactly the same energy seen at CERN, same initial beam preparation etc and then establish if the effect is a function of the distance (proportional to it , the time of arrival difference vs light) as a true superluminal speed would indicate. That would instantly kill a lot of the criticism about the timing process because that error probably is very different for different distances and setups meaning if they could still get ~half the time for say a distance half that of CERN GS (Eg some Japan site Super K test at 300 Km or so ) it would be very interesting confirmation of a real not systematic effect.

Doubts cast on faster-than-light neutrinos experiment: http://www.guardian.co.uk/science/20...?newsfeed=true

Doesn't the last paragraph in that article just make the entire article pointless?

Basically it says the measurements would invalidate our current theories. Our current theories predicts there should be radiation, there is no radiation so the measurement is wrong. But we just said this measurement invalidates our current theories so the new theory just has to include that there is no radiation at these speeds.

To me this means we are still in the same spot and that is trying to invalidate the measurement somehow.

Exactly. I noticed that too a few days ago that i first read the Glashow paper assuming we are talking about the same thing.


The fundamentally bad conceptual problem with the radiation theory claim is that it actually assumes radiation expressions (Glashow paper etc) and theory that are derived within a quantum field theory that assumes Lorentz invariance, Feynman diagrams, Lagrangians, fermion fields etc (inability of a massive particle to go over speed of light by starting smaller and we do know that neutrinos at small energies are smaller than c from supernova observations and no knowledge of a process that it can start at higher than c at generation ) basically all Relativistic quantum field theory and then uses these results to prove the violation is not consistent with this type of physics. Well but of course it wont be consistent necessarily because if there is a violation mechanism all the physics used to derive such radiation cross sections etc go out of the window potentially resulting in very different answers. So how can you use the theory to disprove its violation??? You can only use a theory to prove its inconsistency not the other way unless the other way you restrict yourself to physics that doesnt depend on that theory but of course we have no such avenue since all is founded around Relativity and a new start will need to rederive everything (which of course we will do this century but possibly in ways that doesnt completely kill all results but we cant know which survives and how far it does before such theory emerges to replace Relativity successfully).

I of course still belong in the camp of this being a systematic error and i am sure we will find it or if we dont (say 10^-3 chance or less) we will not invalidate Relativity but better understand its deeper origin. Before that miracle possibility i have some ideas i would love to ask directly the experimenters at CERN and GSasso since the distance that corresponds to 60 ns is only 18 m and i would love to know the geometric parameters of the detector by the way and how is each arrival detection characterized depending on the location of the event in the detector that has size that is easily over order 10-20 m in all 3 dimensions (see pictures of prior links in this thread).

Im wondering what is now being done to confirm/deny the results. First two are what we've seen OPERA do, the others are speculation on my part. Anyone know if these are being done and when we might expect some results from them?

1. OPERA is extending the measurements.
2. OPERA is ruling out some ideas about faults in experimental design.
3. independent confirmation? Are there other cannons that can achieve similar high energy neutrino beams and point them (this is what my highschool level phys brain imagines) at a detector?
4. pointing OPERA at a different detector?
5. measurements of other very high energy particles generated there?
6. testing other implications from the breakage? Im assuming there is no idea on a theoretical basis yet, so this is probably a no.

Is that an ooops???


http://news.yahoo.com/einstein-wrong...020614484.html

told ya so?

Relativity and QM will be both revisited within a decade. But it wouldnt be so stupidly trivial.

Lets wait for official CERN announcement tomorrow but its true anyway that this experiment is useful and the discussion that followed are important. And i am also willing to say that they should continue to test neutrinos for speed over c there and elsewhere but possibly if they ever detect anything like that it will be a lot smaller than the observed initially here. This is why i was skeptic early on because it felt too big of a difference to be due to a fundamental theory deviation.

In what way? QM and relativity are almost surely to be in the exact same position in a decade as they are now.

I bet with whatever my life is worth the next 10 years! ALL IN! I am not implying that theories will be proven wrong or anything just that they will be understood a lot deeper and that understanding will make possible to go in places they both fail as currently stated but we are either unable to test or unimaginative yet to do so.

That's what happened the last 10ish years or so with AdS/CFT and the solution to the black hole information paradox. Granted, it is going to be tough to come up with something that major in the next 10 years.

Say they do find a velocity which is still above c- shouldn`t be just as sceptical since in all probability the neutrinos are travelling at exactly c? Not disagreeing or anything just think the probability the neutrinos are travelling above c to be extremely low. If we do somehow find a particle capable of travelling faster than light couldn`t we expect any velocity >c as opposed to only a small bit faster? Sry for all the noob conjecture

Yes i know what you are talking about (ie look at tachyons, transformation laws etc) but what i am implying is different. If that were to be observed it would not hint tachyons or anything in that direction but rather it would be a statement about spacetime itself and the identification of the limits of Relativity under what we perceive as spacetime today vs what it really is.

Problems discovered by CERN team.

http://www.bbc.co.uk/news/science-environment-17139635

ah okay I think I get you- ty

Was there really much doubt?

Do you think as time moves forward, and problems become "harder", and technology gets "better", major solutions will decrease or increase in frequency? I don't have beef with your post, just curious on opinion.

p.s. I watched First Contact last night, and was reminded of this thread which I've lurked. We're going to need a bit more than zefram cochrane..

It's sort of hard to say. But I think there seem to be periods with faster growth than others. Obviously the quantum mechanics revolution and later putting the Standard Model in it's present form involved a burst of creativity over a short period of time. At present, it is harder to pick out which direction will be the most fruitful...but just recently there was alot of work in short period of time on the 2nd string theory revolution, that I mentioned with led to AdS/CFT and other things so it seems to be a cyclical thing.

That's not only hard to say; it's impossible because it depends on the nature of laws of physics that we know nothing about.

There's the known unknown that qm and gr are incompatible and therefore at least one of them is "merely" a good approximation. similarly, there's the question of wtf dark energy and dark matter are (as well as a number of smaller questions in cosmology and astrophysics). without knowing the answers to those questions, we can't know how likely it is that we find them.

Then there's this massive unknown unknown: wtf is the universe going to throw at us next? Maybe there are other fundamental forces that we know nothing about. Maybe light has a property that we don't know about that invalidates some/most/all of our astronomical observations. Maybe we'll never know.

I have a snippet of a memory from a physics lecture in which my professor said something like "The speed of light is fixed and rigid, but quantum mechanics creates fuzziness..." and I've never really been able to figure out what he was talking about. Is this related to the incompatibility of GR and QM?

If not, is there a non-technical (or not overly technical) explanation as to the nature of the incompatibility?