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Author Topic: faster than light neutrinos, a second experiment apparently confirms it?  (Read 7451 times)

Offline flr

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Offline imatfaal

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From a quick read that looks just the same as the original write up - I am a bit pressed for time today, can you mention where it says that this is new data

Edit

Just found this which bears our the OP

http://blogs.nature.com/news/2011/11/neutrino_experiment_affirms_fa.html

Of course systemic timing and measurement errors will have been duplicated but this does remove the potential for error from the wave form
« Last Edit: 18/11/2011 10:34:14 by imatfaal »
 

Offline neilep

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If it's true (and a s a sheepy i of course have read it in great detail absorbing every fact !!...yeah right !!)...but if it's true...what does it mean for our understanding of everything we know ?
 

Offline imatfaal

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It means that einstein's relativity has a few more limits and provisos than we previously expected.  We have no absolute theories - we have theories that work given certain limits.

Newtonian mechanics works fine for most things - but for the very fast, and the great distances of space we use general relativity.  Concepts of absolute time and synchronicity work very well on earth - but when you are dealing with high speeds and long distances you need special relativity.

Special relativity holds it true that nothing travels faster than light - so the pristine form of special relativity will not stand, but we already know that special relativity does not hold near very massive objects.  ie this will provide another situation in which we need to use a modified model - and it will hint at a grander model that we have yet to discover, but it won't change that much.
 

Offline Fozzie

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But we still have the fact that neutrinos from a recent supernova arrived only a few seconds before the light flash was seen, which seems to contradict the latest findings. If this result was applied to the supernova, we wouldn't have seen the flash until about 4 years later!  ???
 

Offline flr

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It means that einstein's relativity has a few more limits and provisos than we previously expected. 

Few limits? Let me see: What is time and how it flows for those faster than light neutrinos? And how the frame of reference of those FTL neutrinos can be related to ours?
 

Offline imatfaal

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It means that einstein's relativity has a few more limits and provisos than we previously expected. 

Few limits? Let me see: What is time and how it flows for those faster than light neutrinos? And how the frame of reference of those FTL neutrinos can be related to ours?
A much bigger limit is that SR cannot be used for any massive/energetic object except as an approximation.  SR requires flat minkowski space - and the presence of mass/energy will distort that space, so SR is already massively limited and GR must be used in many circumstances.  SR is the limiting case of GR as mass/energy/gravity becomes small - ie in flat space.  We might have discovered another area in which SR is an inappropriate model - but that does not detract from the value of SR, and we will continue to use it in virtually every situation in which we currently do.

its an incredibly exciting discovery - but more in the way that it might point us in the direction of more complete models - rather than over-turning present ones.
 

Offline Soul Surfer

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I have already suggested quite a practical reason for this measurement and that is that the process by which neutrinos go through the nuclei of atoms is quantum mechanical tunnelling and not normal propagation  This is in general considered to be a faster than light process that does not allow information transfer faster than light.  Taking out the time that the neutrinos were passing through nucleii gives the correct result without bending any physical laws.  This faster than light effect would also only apply to neutrinos passing through matter.  If this was the case the main effect would be on neutrino pulses in high density matter like neutron stars.
 

Offline imatfaal

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SoulSurfer - didn't see that post.  Another thread perhaps?  When you say the figures fit - what equationsw/what incidence of tunnelling act are you using? 

I would have thought that if some form of quatum event is allowing some neutrinos to get to gran sasso early, then others should be getting to gran sasso on time (ie have experienced none/fewer quantum events), and others should be even earlier (ie more evnts).  whereas the waveforms detected at cern of the proton beams and the builtup waveforms in gran sasso are same shape and size.  I suppose this contention would be moot if you were suggesting a large enough number of events such that any variation would be small enough as a percentage not to be noticeable. 

Could you direct me to the post where you go into more detail
 

Offline JP

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Tunneling straight through an obstacle should actually be a pretty rare result of firing a particle at it.  In a majority of cases, you'd expect to see it scatter off in another direction.  But in many experiments (including this one) we see that neutrinos scatter off of matter extremely rarely, so tunneling should be even more extremely rare, and couldn't account for the bulk of the neutrinos moving FTL.
 

Offline kevinj

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I have a beginners question will this allow humans to travel backwards in time?
 

Offline flr

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I have a beginners question will this allow humans to travel backwards in time?

If objects with mass (such as neutrinos) can indeed travel faster than light, and unless photons actually do have a rest mass and/or the maximum possible speed is not the speed of light but a bigger one, then I'd rather believe that our current understanding of time/space/causality as derived from relativity would have to change quite a bit. 

I tempted to believe that, if there are particles that can travel back in time, they must always go backward in time. But does actually time indeed have an arrow or it is just that we perceive it that way?

 

Offline Soul Surfer

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i first mentioned this in our earlier discussion  on this topic  http://www.thenakedscientists.com/forum/index.php?topic=41198.0
in my comment  24/09/2011 08:40:33

There are several situations where faster than light movement can occur in all cases the critical feature of these is that they do not allow information to be transferred faster than light.  Quantum mechanical tunnelling describes a process in which a particle can pass through a potential barrier that they could not in theory penetrate but the wave aspects of the particle mean that there is a significant probability that the particle is the other side of this barrier so the particle in effect instantaneously vanishes on one side and appears on the other. it is a bit like the instantaneous effects that happen with entangled particles.

I have not yet seen any other  suggestions that this or something like this could be the reason for the effect.

I also did some simple calculation that if this happened when the neutrinos passed through nuclei and it was instantaneous it would account for this tiny reduction on the time that it takes the neutrino to  pass through solid material.  There is of course absolutely no possibility that much more than this could be achieved in normal material but it might have significant effects in highly compact objects like neutron stars.

There is also an interesting wikipedia article http://en.wikipedia.org/wiki/Faster-than-light which goes through many cases where faster than light effects may be seen.




 

Offline imatfaal

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i first mentioned this in our earlier discussion  on this topic  http://www.thenakedscientists.com/forum/index.php?topic=41198.0
in my comment  24/09/2011 08:40:33

There are several situations where faster than light movement can occur in all cases the critical feature of these is that they do not allow information to be transferred faster than light.  Quantum mechanical tunnelling describes a process in which a particle can pass through a potential barrier that they could not in theory penetrate but the wave aspects of the particle mean that there is a significant probability that the particle is the other side of this barrier so the particle in effect instantaneously vanishes on one side and appears on the other. it is a bit like the instantaneous effects that happen with entangled particles.

I have not yet seen any other  suggestions that this or something like this could be the reason for the effect.

I also did some simple calculation that if this happened when the neutrinos passed through nuclei and it was instantaneous it would account for this tiny reduction on the time that it takes the neutrino to  pass through solid material.  There is of course absolutely no possibility that much more than this could be achieved in normal material but it might have significant effects in highly compact objects like neutron stars.

There is also an interesting wikipedia article http://en.wikipedia.org/wiki/Faster-than-light which goes through many cases where faster than light effects may be seen.

Just did some very rough and shoddy calculations - and the neutrinos would need to tunnel through around 10^15 nuclei which is about the right number they would encounter on a 730km trip.  Interesting idea SSurfer - but from all I have read about q tunnelling it is a highly unlikely act that occurs at the far end of the probability curve, not on every occasion.
« Last Edit: 20/11/2011 09:21:00 by imatfaal »
 

Offline JP

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Again, tunneling is an interesting idea for resolving this measurement, but there are three problems with it, two of which are pretty major.

First, the minor quibble is that its still contentious whether tunneling is a FTL process or not, so we can't go in assuming that it is.  That's minor, though, since this could be the experiment to show that it is.

The first major problem, however, is that we have a good handle on how strongly neutrinos interact with matter, and it is an extremely weak interaction.  This has been verified experimentally (using particle accelerators) and observationally (using solar neutrinos).  Tunneling requires the kind of dead-on collision that will happen exceedingly rarely, so you shouldn't see the kind of pulse advancement that happened in this experiment.  Instead you'd see a few neutrinos tunnel ahead of the bulk of the pulse.

Second, even if we have something wrong and neutrinos tunnel frequently, a collision between particles isn't a tunnel/no tunnel event.  Tunneling is always accompanied by scattering (and reflection).  So for every tunneling neutrino, we'd see many more of them scattering in different directions without needing to tunnel.  Scattering is a pretty obvious signature that this experiment didn't pick up.  We'd also see it in other experiments.
 

Offline yor_on

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And so we proved that mass go FTL, whereas light go as a 'constant' ::))

Nah.
 

Offline Soul Surfer

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We know that the interaction probability of a neutrino with even nuclear matter is very low indeed so scattering or reflection is exceedingly small.  one thing that might help is to consider the neutrinos as a wave and think of its wavelength with respect to the size of a nucleus but I am not sure how we could calculate the wavelength of the neutrinos.
 

Offline JP

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We know that the interaction probability of a neutrino with even nuclear matter is very low indeed so scattering or reflection is exceedingly small.  one thing that might help is to consider the neutrinos as a wave and think of its wavelength with respect to the size of a nucleus but I am not sure how we could calculate the wavelength of the neutrinos.
Ok, I agree the interaction probability is small, but so is the tunneling probability.  They're both dependent on the strength of the potential barrier presented to the neutrino by the nucleus.  But this experiment shows the bulk of the pulse shifted forward to superluminal speeds, not just a few events that happened to interact.  This is inconsistent with the explanation being due to an interaction of any kind, tunneling or not, since the interaction probabilities are so low.
 

Offline Soul Surfer

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I am not sure how you can say that when every neutrino will experience a vast number of nuclear transits during its journey.  it may just be that this is the normal way to behave when neutrinos are passing through small dense areas in the same way that light slows down while passing through glass.
 

Offline JP

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Where's the evidence that it will interact with a vast number of nuclei?  We've established the interaction probability of neutrinos with matter from other experiments and they are incredibly small.  Even if it passes near many nuclei, it won't interact with them. 

Of course, if we're wrong in what we know about neutrinos, perhaps they could interact with a lot of nuclei.  Even in that case, tunneling always happens with <100% probability.  Neutrinos that don't tunnel will scatter.  We don't see any evidence of high levels of scattering in this or other experiments, so tunneling isn't significant.

Using glass as a comparison isn't correct, since the speed of light in glass is controlled by interactions between light and electrons, not by tunneling.  You can get light to tunnel (frustrated total internal reflection), but then you see exactly what I say above: you get a lot of reflection as well as tunneling.
 

Offline Soul Surfer

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The tunneling I am talking about is that seen with electrons in tunnel diodes  see 

http://en.wikipedia.org/wiki/Tunnel_diode

assuming the neutrinos travel in straight lines they will pass through many nuclei on their journey all you need to look at is the statistical cross section of a nucleus compared with the cross sections of the whole atom.

Because of the low overall probability of action the loss during the period of transit through the nucleus is negligible and like a cut off waveguide (another good example of faster than light propagation of a similar type) phase transit time is essentially zero.
« Last Edit: 21/11/2011 15:24:40 by Soul Surfer »
 

Offline JP

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I'm not arguing against tunneling!  It certainly happens.  My problem with tunneling as an explanation for the "superluminal" neutrinos had to do with the interaction probability and the idea that they would strongly tunnel but weakly scatter off of nuclei.  You haven't addressed either of those issues.

To give you an idea of the numbers, roughly 100,000 solar neutrinos pass through the earth for every 1 that interacts with it.  Ok, these are solar neutrinos and they're passing through the entire earth, not just one mountain, but still it's got to be a rough estimate of how likely the CERN neutrinos are to interact with matter on the way to the detector.  Assuming Matthew's right, the neutrinos would have to tunnel (which is an interaction) roughly 10^15 times through nuclei.  The whole pulse pretty much arrives together, so all the neutrinos would have to interact roughly 10^15 times.  This is an enormous discrepancy: we expect from our other observations roughly 10^-5 interactions per neutrino and you're claiming that we're getting roughly 10^15 of them.  That's 20 orders of magnitude off!  Even if my numbers are wrong, or solar neutrinos behave differently than the CERN neutrinos, we've still got to be many orders of magnitude off.  Can you explain how this happens?

Now, even if these 10^15 interactions somehow happen, you still have to explain why the neutrinos almost exclusively tunnel instead of scatter.  Tunneling and scattering are two parts of the same interaction: a wave hits a potential barrier.  Part of the wave will always tunnel and part will scatter.  Yet we don't observe significant scattering over the total 10^15 interactions.  Why not?  Is there something special about neutrino interactions that doesn't happen for other particles? 

I could be way off on my numbers here.  I'm not a high energy physicist, but from what I know about neutrinos and quantum tunneling, the numbers required for a tunneling explanation to hold are so far off from what we've observed in other experiments that it's just not a plausible explanation. 
 

Offline Soul Surfer

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Its just that the tunnelling probability vastly outweighs the scattering probability which is what is observed.  What is wrong with that?  I am not suggesting any process that is different from what is observed. The only thing that I am suggesting is that neutrinos do not just pass through nuclei as if they weren't there which is what is assumed at the moment.  All that i am suggesting is that the neutrinos adopt a tunnelling process which is essentially instantaneous but does not allow information transfer and does not contravene the general rules associated with the velocity of light.

Something like this could explain both results on neutrino speeds and avoid any rule breaking.  What is more the amount of time neutrinos spend passing through the nuclei happens to be a good approximation of the reduction in the path length that has been measured.
 

Offline JP

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Its just that the tunnelling probability vastly outweighs the scattering probability which is what is observed. 

That's one of the issues I have with the tunneling explanation.  Where has this been observed?  What experiments show that neutrinos favor tunneling over scattering in similar circumstances?
 

Offline Soul Surfer

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None.  All I was saying that neutrinos do not interact much and scatter.  Currently the only possible place effects like this could be observed is the current experiment.
 

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