shrooma Posted May 22, 2013 #1 Share Posted May 22, 2013 I came across this article- . https://sites.google.com/site/martinhickescom/test-sheds-doubt-on-faster-than-light-claim . about a mistaken experimental result that showed neutrinos travelling faster than the speed of light. while the flawed data was disappointing, what WAS interesting was the findings of the re-test, that although the neutrinos hadn't achieved superluminal velocity, they WERE travelling at precisely the speed of light. this may be all well & good for a massless particle such as a photon, but neutrinos DO have mass. Einstein's special theory of relativity states that a massive body travelling at lightspeed would have an infinite mass, and would therefore require infinite energy, which is impossible, so how can a particle with mass, a neutrino, contravene these impossibilities and achieve the speed of light? Link to comment Share on other sites More sharing options...
keithisco Posted May 22, 2013 #2 Share Posted May 22, 2013 Dont start me off again I do not, and never have, accepted the received wisdom that Einstein's equations were correct, and I always believed that his thought experiments were seriously flawed (when looked closely at). In fact, when looking at his thought experiments, if you looked at them from BOTH Observable Frames of Reference you always get a NULL result. I.E. Astronauts do not age more slowly when accelerating away from Earth, because (in accordance with both General and Special Relativity) it is actually the Earth that is accelerating AWAY from the Astronauts - dependent on your point of observation Link to comment Share on other sites More sharing options...
ninjadude Posted May 22, 2013 #3 Share Posted May 22, 2013 interesting but All evidence suggests that neutrinos have mass but that their mass is tiny even by the standards of subatomic particles. Their mass has never been measured accurately. https://en.wikipedia.org/wiki/Neutrino Link to comment Share on other sites More sharing options...
Emma_Acid Posted May 22, 2013 #4 Share Posted May 22, 2013 Dont start me off again I do not, and never have, accepted the received wisdom that Einstein's equations were correct, and I always believed that his thought experiments were seriously flawed (when looked closely at). In fact, when looking at his thought experiments, if you looked at them from BOTH Observable Frames of Reference you always get a NULL result. I.E. Astronauts do not age more slowly when accelerating away from Earth, because (in accordance with both General and Special Relativity) it is actually the Earth that is accelerating AWAY from the Astronauts - dependent on your point of observation I'm not very good at this sort of physics, so more than willing to be beaten down about this - but it isn't just two frames of reference is it? If you look at it from multiple it is the space ship that's accelerating. Link to comment Share on other sites More sharing options...
sepulchrave Posted May 22, 2013 #5 Share Posted May 22, 2013 I came across this article-this may be all well & good for a massless particle such as a photon, but neutrinos DO have mass. To be fair, I think most of the evidence for neutrino masses comes from neutrino oscillation. For a neutrino to spontaneously change flavour (from an electron to a tau neutrino, for example), it cannot be travelling at exactly the speed of light, since then it would not experience time. However a superluminal neutrino would experience time backwards, which still allows for oscillation (I don't think anyone can tell the difference between oscillation forward or backward in time). If neutrinos have an imaginary mass; this sort of superluminal velocity may be possible in conventional relativity. (This is obviously very unlikely, for a number of other reasons, but worth remembering. I personally am quite happy to believe the conventional theory of small positive neutrino mass.) In fact, when looking at his thought experiments, if you looked at them from BOTH Observable Frames of Reference you always get a NULL result. I.E. Astronauts do not age more slowly when accelerating away from Earth, because (in accordance with both General and Special Relativity) it is actually the Earth that is accelerating AWAY from the Astronauts - dependent on your point of observation No. Frames of reference are only equivalent when they are inertial. If one observer is accelerating away from another, the points of view of the two observers are no longer equivalent. I demonstrated this in some detail in a previous thread. Link to comment Share on other sites More sharing options...
shrooma Posted May 22, 2013 Author #6 Share Posted May 22, 2013 interesting but https://en.wikipedia.org/wiki/Neutrino . starting mass is irrelevent dude, no matter how small. E=MC2 tells you that the faster something is moving (ie-the more energy it has) the more massive it becomes, and at light speed it would have infinite mass, so even a ghost fart would be infinitely heavy at those speeds, but somehow, neutrinos manage to pull it off! but how?? Link to comment Share on other sites More sharing options...
sepulchrave Posted May 22, 2013 #7 Share Posted May 22, 2013 starting mass is irrelevent dude, no matter how small. E=MC2 tells you that the faster something is moving (ie-the more energy it has) the more massive it becomes, and at light speed it would have infinite mass, so even a ghost fart would be infinitely heavy at those speeds, but somehow, neutrinos manage to pull it off! but how?? I think Ninjadude's point (judging by the emphases in the quote) is that neutrinos are inferred to have a non-zero rest mass based on various other properties. The actual mass of a neutrino has never been measured directly. Neutrinos are assumed to have a non-zero but very small rest mass because then they can exhibit flavour oscillation (which suggests that the neutrino cannot be travelling at the speed of light) but also exhibit an almost-unchanging chirality (which is only a true invariant for particles travelling at the speed of light). However there could be something else at work; it is possible (although unlikely, in my opinion) that neutrinos are massless. 1 Link to comment Share on other sites More sharing options...
shrooma Posted May 22, 2013 Author #8 Share Posted May 22, 2013 QUOTE- . MINOS (2012) The MINOS collaboration further elaborated on their speed measurements of 2007. They examined the data collected over seven years, improved the GPS timing system and the understanding of the delays of electronic components, and also used their upgraded timing equipment. They obtained (part missing) nanoseconds. This is consistent with neutrinos traveling at the speed of light, and substantially improves their preliminary 2007 results. . this is the latest and most accurate test (so far!) of neutrino speed sepulchrave, that shows neutrinos travelling at the speed of light. neutrino mass cannot be calculated by their speed because of this, but yet they ARE found to be massive. if they ARE travelling at light speed, as the test shows, could (theoretically) some mechanism of Very Special Relativity be responsible? Link to comment Share on other sites More sharing options...
Taun Posted May 22, 2013 #9 Share Posted May 22, 2013 Since Neutrinos are a part of the physical universe (i.e. they are here - not some other dimensional manifestation - or whatever) ... and since they act according to their nature... It is safe to assume that they do not contravene the rules of physics... They operate within the rules - we just might not know all of the rules yet... Link to comment Share on other sites More sharing options...
bmk1245 Posted May 22, 2013 #10 Share Posted May 22, 2013 (edited) [...] This is consistent with neutrinos traveling at the speed of light, and substantially improves their preliminary 2007 results. . this is the latest and most accurate test (so far!) of neutrino speed sepulchrave, that shows neutrinos travelling at the speed of light. neutrino mass cannot be calculated by their speed because of this, but yet they ARE found to be massive. if they ARE travelling at light speed, as the test shows, could (theoretically) some mechanism of Very Special Relativity be responsible? Is traveling at 99.999999% speed of light is at the speed of light? Is traveling at 99.99999999999% speed of light is at the speed of light?Estimated mass of neutrinos are in few eV range in comparison of electron with ~500 keV mass, i.e. electron is at least 5 orders heavier than neutrino. With SN1987A, I think, there is little doubt neutrinos travel underluminal... Sepu may shed light on that. Edited May 22, 2013 by bmk1245 Link to comment Share on other sites More sharing options...
shrooma Posted May 22, 2013 Author #11 Share Posted May 22, 2013 Since Neutrinos are a part of the physical universe (i.e. they are here - not some other dimensional manifestation - or whatever) ... and since they act according to their nature... It is safe to assume that they do not contravene the rules of physics... They operate within the rules - we just might not know all of the rules yet... . but by travelling at the speed of light AND having mass, they DO seem to be breaking the rules taun, which is why your comment of us 'not knowing all the rules' is the only logical supposition we can make! Link to comment Share on other sites More sharing options...
shrooma Posted May 22, 2013 Author #12 Share Posted May 22, 2013 Is traveling at 99.999999% speed of light is at the speed of light? Is traveling at 99.99999999999% speed of light is at the speed of light? . so you're just ignoring the result that says 'this is consistent with neutrinos travelling at the speed of light' then huh? by quoting from an earlier, less accurate test? not exactly what I had in mind when I posed the question. Link to comment Share on other sites More sharing options...
bmk1245 Posted May 22, 2013 #13 Share Posted May 22, 2013 . so you're just ignoring the result that says 'this is consistent with neutrinos travelling at the speed of light' then huh? by quoting from an earlier, less accurate test? not exactly what I had in mind when I posed the question. Nope, I'm just ignoring pop-sci "news", aka put word here, delete this/that, looks nice now... Link to comment Share on other sites More sharing options...
shrooma Posted May 22, 2013 Author #14 Share Posted May 22, 2013 (edited) Nope, I'm just ignoring pop-sci "news", aka put word here, delete this/that, looks nice now... . *yawn* the quotes are taken from the june 8 edition of 'Fermilab Today' and hardly what you'd call 'pop-sci' ''news'' unless you refute the findings of one of the most prestigeous & respected group of physicists on the planet? or maybe you know better than them? Edited May 22, 2013 by shrooma Link to comment Share on other sites More sharing options...
sepulchrave Posted May 22, 2013 #15 Share Posted May 22, 2013 this is the latest and most accurate test (so far!) of neutrino speed sepulchrave, that shows neutrinos travelling at the speed of light. neutrino mass cannot be calculated by their speed because of this, but yet they ARE found to be massive. if they ARE travelling at light speed, as the test shows, could (theoretically) some mechanism of Very Special Relativity be responsible? The latest MINOS results for the speed of a neutrino can be seen on the last page of this presentation. The results suggest that the neutrinos reached the target some 734 km away at speeds somewhere between 99.998% and 100.001% the speed of light. As bmk1245 mentions, the rest mass of a neutrino is expected be only a few eV (or less). Since the neutrinos produced by the source for MINOS (the NuMI reactor) have kinetic energies between say 10 and 50 GeV, these neutrinos should be travelling basically at the speed of light. For example, if the kinetic energy of a 10 eV neutrino (which is possibly on the heavy side, but also close to the rough estimates from the supernova bmk1245 mentioned) is 10 GeV, the neutrino will be travelling at (1 - 0.5 x 10-17) = 99.999999999999995 % the speed of light. So for the expected neutrino mass and the range of neutrino energies produced by NuMI, these neutrinos fit within the velocity bounds of the MINOS experiment. MINOS only shows that the neutrinos produced by NuMI are travelling somewhere between 99.998% and 100.001% the speed of light. There is not enough evidence to show that they are travelling at 100% the speed of light, or slightly above, or slightly below. Only that their true speed is somewhere within that range. Therefore, at the moment we can't say that neutrinos violate the rules of General Relativity. The expected velocity of 10 - 50 GeV neutrinos with rest masses of a couple of eV is well within the 99.99% to 100.001% of c bounds set by MINOS. 1 Link to comment Share on other sites More sharing options...
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