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Q & A: faster than light neutrinos?

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Most recent answer: 01/26/2012
Q:
"Neutrinos clocked moving at faster-than-light speed" This is not a surprise. It at least supports a doubt I have had for a while: That the speed of light is NOT a constant (in the equation E=MC2). Why? In short, this is because, light, like everything else that has a physical speed defined, must have acceleration. Light accelerates from zero to 299,792,458 m/s in how much time? There is no real answer to this question per the equation. However, is it possible that if a ray of light emitted from a source moved in a circular orbit that just gets bigger, and the RADIUS of the light disc (created by orbit) could progress at a constant speed, while the ray of light itself does posses accelaration?
- Gautam Sharma (age 39)
Redondo Beach, CA
A:
You have the honor of being the first to ask us about the new results from OPERA, in which their measurements indicate a neutrino speed faster than light.

I must say (we'll soon hear Lee's views as well) that I believe the result is mistaken. The experimental group has a very good reputation and tried very hard to be careful about this difficult experiment. They also indicate that it's too weird a result to simply accept yet. The reason is that the entire structure of modern physics is built around Special Relativity, which has allowed a huge number of extremely precise predictions, but does not allow things like neutrinos to exceed the speed of light. Usually (but not always) when some result contradicts an extremely well-tested general principle, the problem is with the result, not the principle.

As background, it's known from supernovae observations that low-energy neutrinos travel at speeds extremely close to c. The latest experiments concern higher-energy neutrinos, so in principle they aren't in direct disagreement. Still, of all the ways that we think our basic principles might break down, this seems like one of the least likely.

As for the parts of your question about light circling around, etc., I can't quite follow it.

Mike W.

I plowed through their paper    and could not see any glaring errors.  In fact the authors have investigated many more possible sources of measurement uncertainties than I could think of.   The OPERA group is well respected in the physics community and their result has to be considered very seriously.
Nevertheless, like Mike, I am very reluctant to give up my cherished  theory of Special Relativity.  So many experiments have been performed in the past on speed of light phenomena that have given the same result, including light itself as well as particles with mass such as electrons or muons.    No doubt other experimental groups will be hot on the trail to verify or deny this result.  If it is true I'm going to throw out all my physics books and start reading Tolstoy's 'War and Peace'.   Stay tuned.

LeeH

Feb. 22, 2012: breaking news:

Feb. 22: Today the news came out that a loose connection in the experiment caused a 60ns timing error. It could turn out to be that simple. Mike W.

(published on 09/22/2011)

Follow-Up #1: OPERA, neutrinos, and backwards time

Q:
This doesn't make any sense...How would time dilation react for things travelling faster than c? They would be sent into their own past? Backwards time travel is impossible, it doesn't make even sense. Same thing for breaking the light barrier. They say that the neutrinos arrived sooner than light would have by a billionth of a second. Is there only me in the whole world to consider that at this tiny scale, error margin should be very high? If these results are proven true and that light isn't the ultimate speed, then I'm willing to believe in a christian God punishing people in Hell for eternity for sins committed in a finite life!!! Amen!
- EinsteinISright
A:
You have correctly described some of the paradoxes that would arise if:
1. the new OPERA neutrino results are correct
and
2. The Lorentz transforms of Special Relativity are the correct way to translate coordinates between different reference frames in which the same laws of physics can be used.

So the basic conclusion is that if (1) is right then (2) isn't. The accumulation of evidence for Special Relativity is so enormous and varied that Lee and I are very strongly inclined to go with (2) over (1).

It wasn't clear if you were implying that the OPERA group deserved eternal punishment for their misdeeds. To be fair, the OPERA group has done what seems to be a very careful job looking for possible errors in their 60 ns (not 1 ns) effect. They've done something unusual (and, I think, admirable) in putting this crazy result out for everyone to inspect and for a few groups to try to replicate, without claiming that it is enough evidence to overthrow SR yet.


Mike W.



(published on 09/23/2011)

Follow-Up #2: CERN neutrinos through a wormhole?

Q:
Is it possible that the neutrinos went through a microscopic worm hole? That would explain why they arrived sooner than expected and SR would still be intact proven that results are indeed true!
- Anonymous
A:
Here's a first response, which may get updated if we hear from more knowledgeable colleagues.

The problem is that if you make an SR (Special Relativity) picture of the 3+1 dimensional space of this particular experimental result, in some reference frames the neutrinos traveled backward in time. Allowing for backwards-in-time travel of information leads to all sorts of horrible science-fiction paradoxes. So there are big problems reconciling this sort of event with SR.

Now it's true that SR is only a limiting case of GR, applicable to flat patches of space-time without major gravitational effects. Nevertheless, the possibility raised by GR of backwards time travel via wormholes has always been a serious worry. The usual suspicion is that no information could survive such travel in a fully quantized description. This neutrino business would eliminate that loophole, in the unlikely event that it turns out to be correct.

Of course there are other problems: what sort of micro-wormhole would be stable and moving along with the earth for the duration of the experiment? Etc. So either there's a calibration error of some sort or there's a true revolution in physics. We expect revolutions in physics, and soon, but we certainly haven't been expecting one like this right in the middle of what seems to be a well-understood domain.

Word on the street is that other geometrical modifications, involving higher dimensions, are a more plausible interpretation if somehow the result turns out to be right. These interpretations still involve the loss of Special Relativity right in the range where it has seemed to work so well.

Mike W.

(published on 09/25/2011)

Follow-Up #3: CERN and massive photons?

Q:
What is your take on the CERN findings of neutrinos travelling faster than light? If this finding were confirmed how would this change physics and what would it mean for current theories? Could it be that photons do have mass (but it is simply impossible to measure because they are always in constant motion) and that neutrinos just have a slightly smaller mass? Maybe in this case the new "cosmic speed limit" would be that of neutrinos? I know this may not make sense, but then again neither does something going faster than the speed of light.
- Scott Robbins (age 16)
Massachusetts, USA
A:
I've marked your question as a follow-up to ones that address parts of it. The new part concerns the possibility that photons have some rest mass. That in itself wouldn't make problems for SR. All it would mean is that "c" in the basic equations wouldn't actually be the speed of light.  However, there's an enormous body of experimental data showing that the rest mass of light is truly zero, at least on the scale relevant for this experiment. Otherwise, there would be a frequency dependence to the speed, which would show up dramatically in arrival times of bursts of light from very distant objects.

Mike W.

(published on 11/03/2011)

Follow-Up #4: superluminal neutrino follow-up

Q:
WHat's the latest on superluminal neutrinos?
- dr d (age 70)
geneseo ny
A:
Not much has changed. The CERN group checked certain parts of their timing, confirming their previous results. We're all waiting for more fully independent checks from Fermilab and from Japan.

Mike W.

(published on 11/30/2011)

Follow-Up #5: More information on faster than light neutrinos

Q:
Here's an interesting article about ICARUS who refutes OPERA findings. Mike and LeeH, what do you guys think? http://www.science20.com/quantum_diaries_survivor/icarus_refutes_operas_superluminal_neutrinos-83684
- Anonymous
A:
The ICARUS result is based on measuring the energy spectrum of the emerging neutrinos in the Gran Sasso detector and comparing it with a theoretical prediction by Cohen and (Nobel Prize winner) Glashow. No timing is used in this measurement, only the energy spectrum of the neutrinos.  According to C&G, if the neutrinos were going faster than the speed of light they would lose some energy and the measured spectrum would change significantly.   No change, within statistics, is observed.  I read the ICARUS paper, it looks good to me.   My money is still on Einstein.
By the way, the blog by Tommaso Dorigo is one of the best in the high energy field. You can rely on his comments. 

LeeH


(published on 12/01/2011)

Follow-Up #6: CERN neutrinos?

Q:
You Said that nothing can travel faster than light. But recently at CERN a sub-atomic particle named 'neutrino' travelled faster than light. How is that possible?
- Razin Shaikh (age 13)
India
A:
Razin- I've moved your question to follow-up on ones that probably already give the answer.

Mike W.

(published on 01/26/2012)

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