quantumtopology

That reliability is precisely what you lack in a experiment with neutrinos by definition, due to the weak interaction being ... weak, basically. Exactly, so why do you assume the other necessities are met? Surely you are aware of the distiction between FTL signals and sending useful information FTL. The former doesn't guarantee the latter. I'm afraid it's gonna be a tough one winning the lottery :angry: ;) Actually both exploit the quantum tunneling effect (according to wikipedia), virtual particles effects and negative or at least less than unity index of refraction materials. So to me conceptually they are quite similar. This paper by Scharnhorst himself is very clear about his effect not violating causality: http://arxiv.org/PS_cache/hep-th/pdf/9810/9810221v2.pdf

Hmm, yes, somewhat like a virtual quantum particle, let's keep in mind we actually don't detect the neutrinos proper but their effects on electrons, muons etc. You might argue that something similar can be said of photons but they have the advantage that they interact electromagnetically and can be detected in a one photon-one hit basis.

Don't you see as a limitation the fact that it is impossible to predict if an individual neutrino sent at one point will be detected at the other? I mean they needed 10^20 neutrinos to obtain 10^4 detection events after a few years. I would say this limits sending any information faster than light that differentiates itself from random noise no matter how strong the emitter is (and there's also energy limitations to that). I'm not sure but I don't even think for instance Nimtz claims that his experiments defy causality, only that they show Lorentz violation, actually here http://arxiv.org/abs/physics/0009043 Nimtz claims causality is preserved. Certainly the closely related Scharnhorst effect in the words of Scharnhorst himself according to wikipedia argues that the effect can't be used to create causal paradoxes.

I find this point of view very interesting, the thing is if after all this turns out to be a quantum effect it wouldn't have such tremendous impact in relativity as the media and many scientists claim, what I mean is that we have always known that some "non-local" quantum effects seem to defy c as a limit, I'm thinking of the EPR experiments etc, the key point about all of them is that this "non-locality" can't be used to send information faster than light so relativity remains fine. I think the same situation appear here in the way the neutrinos are detected, wich can only be in a statistical way, that is there's no way we can send a neutrino and be sure that one will be detected, we need to send zillions to recover a few of them. All this of course provided it is not due to some error in the latency time claculation or some bias in the detected neutrinos wrt the pulse waveform. Where I do see some new physics is in the fact that it is hard to see how neutrinos could have some mass from these results, it would look like at the very least they travel at lightspeed but this contradicts flavour oscillation. It's all really odd. Ok, I see, thanks.

I have next to zero knowledge about particle physics, so this may be a dumb question, do they have a baseline number of neutrino detection events when the accelerator is off? I would bet that count should be really low if they only obtain 15000 with the beam on, but I'm curious about this specific figure. Thanks

Hi Qfwfq, I agree with you, even if the results are confirmed we should be careful with the interpretation, the media and some scientists are drawing all kind of absurd conclusions. IMO questioning relativity is the last option not the first, because the implications would deny almost a century of very accurate experiments. Apparently serious researchers are looking at the fit between the pulses sent from the CERN and the detections at Gran Sasso, and some assumptions like the 10 microseconds lapse pulses from CERN having the same event probability at the detection end, are being questioned. On the other hand certainly before declaring relativity and thus practically all of modern physiscs dead we should also reexamine assumptions about the nature of neutrinos, a particle that has had some exotic features from its theorizing by Pauli and posterior indirect detection. Some speculate that maybe some of the detected signals may not be coming from the CERN, being local instead, related to the vacuum energy fluctuations. There's a lot to be done before though, like replicating the results by another team.

I don't doubt this, never crossed my mind that you might wanna mislead anybody. I'm just trying to reach a minimum common ground, and judging by your post we are very close to it. In fact most of wat you explain in this post I agree with except something that is central to the discussion and that migh be the origin of misunderstandings Sure. This specific part of the paper is needed to fit reality to the standard model, and obviously does not make physical sense. Now you are confusingly using the concept and the word static, I think you know that when we(CC and I) talk about static spacetime or static metric that has a very specific meaning in differential geometri and general relativity, that has nothing to do with considering all objects to be frozen and unable o move, otherwise you would calling us stupids, I'm sure you are aware that I never implied that a car never crash or that clocks get suspended in the air if I use a different coordinate that gives me its redshift as gravitational, that is why puzzles me that you keep making this comments, unless you use them as strawman arguments. Sure. So let's talk about not having prejudices about situation with only one physical outcome, I repeat again that using a static metric doesn't mean cars don't crash or clocks don't fall under gravity influence, or galaxies are not in inertial motion, if you really believe I think that,no wonder we disagree. All I say is that is equally erroneous to think that using a determinate coordinatesand metric, the FRW coordinates means that galaxies are accelerating away from us, you can't say that and that they are in inertial motion a t the same time, if they are accelerating away certainly something else than gravity is acting, they call it dark energy or positive lambda to salvage the expanding model but if something like that is really acting on galaxies they should "feel" accelerated and would not be in free fall.

No, they don't with the choice of coordinates that allows the interpretation as gravitational redshift, that is explained in the paper, from page 7: "To construct the gravitational family of observers, we require that each member be at rest relative to her neighbor at the moment the photon passes by, so that there are no Doppler shifts. Initially, it might seem impossible in general to satisfy this condition simultaneously with the condition that the first and last observers be at rest relative to the emitter and absorber, but it is always possible to do so. One way to see that it is possible is to draw a small world tube around the photon path as in Sec. III. Within this tube, spacetime is arbitrarily close to flat. We can construct “Rindler elevator coordinates,” the special-relativistic generalization of a frame moving with uniform acceleration, within this tube, such that the velocities at the two ends match up correctly.30 The members of the gravitational family are at rest in these coordinates. Because they are not in free fall, the members of the gravitational family all feel like they are in local gravitational fields. Because each has zero velocity relative to her neighbor when the photon goes by, each observer interprets the shift in the photon’s frequency relative to her neighbor as a gravitational shift. Because the two families exist for any photon path, we can always describe any frequency shift as either Doppler or gravitational." And see also section V: Why interpretation matters So the increase of distances you talk about is purely coordinate dependent. In other words it is a property of a congruence, the one defined by the canonical observers in a FRW metric. It's not a property of spacetime. Another more general set of fundamental observers, independent of FRW symmetries, is defined to be at rest in normal coordinates. Expansion vanishes if you use these observers. What happens in a de Sitter universe could have superficial resemblances with what we are discussing here but we are not dealing with such universe here so it could confuse rather than clarify, our universe is not empty.

Let's see if we can all agree on something. We agree on the Equivalence principle. We agree that cosmological redshift (under the apropriate coordinates, see link below) in as much as it can be translated to a radial velocity is a Doppler redshift. We aree that judging by redshift and brightness measures of supernovaeIa we seem to be in a constantly accelerating frame of reference (usually alluded as accelerated expansion). If we put this three facts together, by the equivalnce principle an constantly accelerated frame is Physically indistinguishable from a gravitational field, and it follows that the cosmological redshift can be interpreted both as a gravitational redshift and as doppler redshift in a constantly accelerating universe. If this considerations hold we all are right in a certain way , we are just looking from different sides of the coin. CC and I look at distant galaxies as if they were in a gravitational well with curvature proportional to distance, and the standard view is to see them as accelerating away from us, but it's just points of view, the physics are the same. I include a link from a completely mainstream cosmologist, a collaborator of Jim Peebles (if someone defines and decides what Mainstream in cosmology is, that is Jim Peebles) named David Hogg, specially in the last two pages he gets to the same point as me via a completely different reasoning, but you'll see, Modest, that is perfectly possible to consider cosmological redshift as a gravitational redshift without even getting out of hard Mainstream cosmology. Whether or not this makes the concept of "expansion" totally devoid of any explanatory power, is debatable, and I'm not gonna try to convince anyone, if someone is fond of the "expansion"picture is fine with me, as long as it is acknowledged that in the gravitational redshift interpretation of cosmological redshift, that picture is unnecesary. http://arxiv.org/abs/0808.1081

Hi, Modest, CC and everyone: This interesting article seems to address some of the points we are debating about assumptions of homogeneity, it's fro 2007 but I think we are basically at the same point. Take a look: http://magickriver.blogspot.com/2007/10/is-universe-fractal-by-amanda-gefter.html Regards QTop

You are close but in fact both assumptions follow from each other, If one drops the cosmological principle it seems the most natural thing to assume Local Lorentz invariance that applied to every point which should leave space statistically homogenous, that is, spatially homogenous in any coordinate(which equals spacetime isotropy), and viceversa if one assumes spacetime isotropy then obviously one must drop the cosmological principle. In any case it all comes dow to change the assumption of the cosmological principle that demands a privileged coordinate spatial homogeneity, and this should depend on purely empirical observations like large scale galaxy surveys: SDSS, 2MASS etc, and they seem to be starting to give us hints that coordinate preferred spatial homogeneity is not the case. I moreless agre with you here , with a precission, General covariance would not demand it in general, unless you considered the matter distribution of the universe in terms of isotropy and homogeneity as a fundamental physical law of our universe. In wich case it would violate general covariance if a differentiable transformation of coordinates changed the form of the law. (from the genral covariance definition of wikipedia). The problem is that I'm not at all sure the distribution of matter in the universe can be considered a physical law, most likely not, it is a purely observational issue. What? Oh, my... here means ??

Oh, no problem, whenever you have the time, and if you please could addres my post 679 too, I'm interested in your opinion. Thanks

By the way Modest, what do you think of the homogenous solution of the link CC gave? http://www.springerlink.com/content/k550472m97528233/fulltext.pdf Actually, I think it is not a "homogenous solution" in the sense we normally refer to: as "spatially only" homogenous solution. However is not inhomogenous as its equations give a contant density not dependent on radius. I'm trying to find the flaw, do you see some obvios flaw? Regards QTop

This is tricky, if we strictly follow relativity and consider that Lorentz invariance is valid in a curved spacetime, then there is no acceptable concept of "cosmic time" or any global time scale, as time changes with distance. That seems reasonable if we take note of the fact that when we look at spatial distances we are observing also the past or look-back time. This admittedly is not the case in standard cosmology where a certain coordinate choice is privileged (the one that originates the FRW metric) and assumed to posses special features such as spatial homogeneity in time spacelike hypersurface slices.And therefore a preferred "cosmic time". According to GR, there is nothing wrong with choosing a coordinates for practical and convenience reasons, as all coordinate choices should give us the same results in physical experiments. But then we must be coherent and we shouldn't decide that the purely spatial isotropy and homogeneity we seem to get with a coordinate choice is physically relevant if it doesnot appear with other coordinate choices as GR general covariance demands. Besides, there is reasons to suspect that the apparently "only spatial" isotropy and homogeneity of the universe with the FRW metric is a coordinate artifact, apart from the fact that it doesn't show up with other coordinates, it demands a certain uniform velocity to be comoving with a supposed flow, and in doing this it is giving us a way to make "closed experiments" of spatial isotropy (see: http://www.phys.ncku.edu.tw/mirrors/physicsfaq/Relativity/SR/experiments.html#Tests_of_isotropy_of_space ) that allows us to distinguish different inertial frames, this is forbidden by the SR principle. Regards QTop

What do you mean by positioned isotropically. Isotropy in our universe is considered pretty much empirically confirmed and I thought according to the copernican principle and cosmological principle (no special place principle) that means isotropy does not depend on position. IOW, if we had isotropy in one location and not in others there would be no homogeneity and the place with isotropy should be at the center, in a special or privileged observing point.