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FTL Neutrinos Explained... Maybe

Soulskill posted more than 2 years ago | from the a-definite-possibility dept.

Science 226

The Bad Astronomer writes "A new paper, recently posted on the arXiv physics preprint server, claims to have explained the faster-than-light neutrino experiment from last month. The author claims the motion of the GPS satellite introduces a relativistic dilation that accounts for the now-infamous 60 ns discrepancy in neutrino flight time. However, I'm not so sure; the original experimenters claimed to have accounted for relativistic effects. I don't think we've seen the end of this just yet."

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226 comments

Having Read Both Papers (2, Interesting)

eldavojohn (898314) | more than 2 years ago | (#37726724)

(Although I am not a physicist) I understand that this is talking about the concept of "time" from a frame of reference between the GPS satellites and the ground stations. However, the original paper's implementation did not measure time with GPS satellites (that would be silly). Instead, it used the satellites to obtain very precise distances and when they did this, they accounted for relativity. The time recording devices were atomic clocks at the locations of the facilities on the surface of the Earth. As the second article notes, they just said they did this and you assume they did it correctly. However, if they miscalculated relativity between the satellites and ground stations, it's going to be in the form of the distance being incorrectly measured -- not the actual time itself. And that distance (which would be slightly shorter than they calculated) should then result in an explanation of the nanosecond difference.

Re:Having Read Both Papers (2)

SoapBox17 (1020345) | more than 2 years ago | (#37726786)

GPS already normally accounts for relativity.... nothing new there. Base on the original paper I think it's highly unlikely they mismeasured the distances. http://www.astronomy.ohio-state.edu/~pogge/Ast162/Unit5/gps.html [ohio-state.edu]

Re:Having Read Both Papers (2)

Vellmont (569020) | more than 2 years ago | (#37727534)

The paper doesn't claim that the distances were measured incorrectly, it claims the timing was inaccurate do to special relativity (not general relativity which another poster in this thread was confused by.

In essence, the paper makes the claim that the experiment is using GPS as a reference clock, and the reference clock (the satellite) is in motion differently, relative to the neutrino source, and detector.

Re:Having Read Both Papers (5, Interesting)

tftp (111690) | more than 2 years ago | (#37727560)

60 ns translates into 18 meters at the speed of light. If the error was that large any car GPS device would be showing you as driving on some other street.

I was working with some high precision GPS receivers [trimble.com] , and they can place you on the map with accuracy of a couple of centimeters. The shape of the Earth is also pretty well understood now.

One unfortunate possibility would be that the clocks are wrong. They had to move them between sites, since they weren't willing or able to synchronize them over the radio where they are (the varying propagation paths would be hard to deal with.) A more pleasing (to me) outcome would be that FTL is real.

Re:Having Read Both Papers (1)

Rich0 (548339) | more than 2 years ago | (#37727818)

60 ns translates into 18 meters at the speed of light. If the error was that large any car GPS device would be showing you as driving on some other street.

Not if the map is also off by 18 meters. How do they put the roads on the map in the first place? Most likely, by GPS, or whatever GPS was calibrated against when it was implemented.

I'm not qualified to judge if the paper is right, but it is very easy to get into circular reasoning when it comes to standards - deriving true standards to that level of precision is hard so lots of stuff gets derived and if anywhere on the chain something goes wrong you can get lots of results that agree and yet are all wrong. Systematic error, and all that.

Re:Having Read Both Papers (3, Interesting)

tftp (111690) | more than 2 years ago | (#37727884)

Not if the map is also off by 18 meters. How do they put the roads on the map in the first place? Most likely, by GPS, or whatever GPS was calibrated against when it was implemented.

The current datum [about.com] for GPS is WGS84. Locations of many places on Earth were carefully measured for centuries, using astronomy and trigonometry. I don't know if they are accurate enough to calibrate the GPS.

A systematic, uniform error, like a translation of the entire datum, would have no effect on the OPERA experiment - however you slide or rotate the outer shell of a sphere it doesn't change the distance between two points. It would require a systematic but non-uniform error to cause this effect. I guess it is possible, since there is no explanation so far of the OPERA results. Such an error has to be location-specific and it should be invisible to the WAAS.

Re:Having Read Both Papers (1)

Man On Pink Corner (1089867) | more than 2 years ago | (#37727674)

Not only that, but my understanding is that GPS timing was used only for time-transfer purposes, to calibrate the local cesium standards were used for the actual measurements.

The bug in the measurement, if there is one, cannot possibly be related to the use of GPS for timing.

Re:Having Read Both Papers (2)

Dan East (318230) | more than 2 years ago | (#37726788)

I don't understand this as well. Either this is simply a preexisting inaccuracy in all GPS readings due to relativity that has never been taken into consideration (highly unlikely), or there's something else going on that I don't grasp. I don't see how the neutrino motion relative to the motion of the satellites is a factor here, as no direct measurement between the two is being made in that way.

One of the things the GPS system helped prove was that relativity is real and must be accounted for in systems of that sort, otherwise accuracy will suffer. So I find it very unlikely that something that fundamental was overlooked in the GPS measurements generically.

Re:Having Read Both Papers (3, Funny)

MichaelSmith (789609) | more than 2 years ago | (#37726876)

Maybe its because GPS understands relativity well enough to get planes to the correct runway, and cruise missiles to their target, but the people who designed it didn't anticipate measuring the speed of neutrinos.

Highly Doubtful (5, Interesting)

Roger W Moore (538166) | more than 2 years ago | (#37727106)

Maybe its because GPS understands relativity well enough to get planes to the correct runway...

GPS understands relativity well enough to require General Relativistic corrections. This paper suggests that the GPS clock is inaccurate and suffers a lag based on location which, since GPS requires accurate timing to pinpoint your location a 64ns time difference would put you 20m off your correct location. In addition the author uses a very simplistic model of GPS clock and satellite for getting the clock. I would also have assumed that the GPS clock is based on multiple satellites since it has to know your location to calculate the propagation delay and it does this by comparing one satellite clock to another.

However the final nail in the coffin is that he doesn't know how to spell photon (it is not spelt foton!)...so I have extreme doubts that this is paper is correct. In fact I'd need to hear from a GPS expert that his simplistic model is reasonable because I don't believe that it is (but then I'm not a GPS expert!).

Re:Highly Doubtful (4, Informative)

digitig (1056110) | more than 2 years ago | (#37727334)

Maybe its because GPS understands relativity well enough to get planes to the correct runway...

GPS understands relativity well enough to require General Relativistic corrections. This paper suggests that the GPS clock is inaccurate and suffers a lag based on location which, since GPS requires accurate timing to pinpoint your location a 64ns time difference would put you 20m off your correct location. In addition the author uses a very simplistic model of GPS clock and satellite for getting the clock. I would also have assumed that the GPS clock is based on multiple satellites since it has to know your location to calculate the propagation delay and it does this by comparing one satellite clock to another. However the final nail in the coffin is that he doesn't know how to spell photon (it is not spelt foton!)...so I have extreme doubts that this is paper is correct. In fact I'd need to hear from a GPS expert that his simplistic model is reasonable because I don't believe that it is (but then I'm not a GPS expert!).

I'm not an expert either although I have worked on GPS aircraft navigation and augmentation systems. You are right that the GPS clock is based on multiple satellites. A GPS fix needs a minimum of four satellites, and the receiver triangulates position in 4-dimensions: the three spatial dimensions and time (four unknowns, four data points). What's more, those 4 will not be in the same plane (the satellites themselves form 6 orbital planes), so the bit in the article about "The orbits of these satellites are at 20.2 106 m from the earth’s surface in a fixed planes inclined 55 from the equator with an orbital period of 11 h 58 min [3]. This implies that they fly predominantly West to East when they are in view of CERN and Gran Sasso, which is roughly parallel to the line CERN-Gran Sasso" looks to me like a fundamental misunderstanding of the satellite orbits. The satellites on which a time fix is based will not all be travelling in the same direction. It is possible to use other position information as data points, and so reduce the number of satellites needed for a fix, but I'm not sure why anybody would do that when they can improve accuracy by using all visible satellites (and anyway, even if they did use a single satellite plus accurately known spatial position, the author of the paper still wouldn't know which orbital plane the satellite used was, and so wouldn't know the direction of movement).

Re:Having Read Both Papers (1)

flosofl (626809) | more than 2 years ago | (#37726918)

I think the fact that most of us are not qualified to understand the raw data let alone the analysis, lends to believe this summary (and associated article) are vastly oversimplified.

That it's taken a relatively decent amount of time for this to come out leads me to believe that the answer is non obvious and non trivial to obtain.

Re:Having Read Both Papers (0)

Anonymous Coward | more than 2 years ago | (#37727028)

"This calls for a very special blend of psychology and extreme violence" - Vyvyan "The Young Ones"

Sorry for being off topic. This is one of my favorite shows of all time. Not many remember it now but, damn, it was a very amusing show.

Re:Having Read Both Papers (0)

Anonymous Coward | more than 2 years ago | (#37727000)

Uum, isn't the resolution that GPS can give you ridiculously low for doing physics experiments, even with access to the military-quality signal?

Re:Having Read Both Papers (1)

digitig (1056110) | more than 2 years ago | (#37727436)

Uum, isn't the resolution that GPS can give you ridiculously low for doing physics experiments, even with access to the military-quality signal?

The civilian specification is that absolute time accuracy is +/- 100ns (95% if I recall correctly) although the system routinely achieves +/- 10ns accuracy (not least because the 100ns specification was set when only L1 was available to civilians so GPS on its own couldn't be corrected for ionospheric effects). What's more, for these experiments it's not the absolute time that matters, it's drift over a very short time that matters. In other words, standard GPS is more than good enough for the CERN experiment (and working in a known fixed location it's fairly straightforward to improve on it still further).

Re:Having Read Both Papers (1)

mark_elf (2009518) | more than 2 years ago | (#37727928)

CERN has its own very accurate time product. There is a team at JPL that uses it and others to determine earth orientation. Altogether it might be the most accurate time product in the world. It's definitely more accurate than GPS and definitely available to scientists at CERN. If they were using GPS for this they are a bunch of mooks even if GPS was "good enough".

Re:Having Read Both Papers (1)

shentino (1139071) | more than 2 years ago | (#37727354)

A network where big fat milliseconds are eaten up merely by the speed of light delaying things imply an uber extreme tolerance requirement.

I'd double check and see simply if error bounds are tight enough.

Re:Having Read Both Papers (5, Interesting)

ETEQ (519425) | more than 2 years ago | (#37727386)

(I *am* a physicist) Actually, the original paper *did* measure time with GPS - more to the point, they use GPS to establish a common frame between the two locations. Look at Figure 5 of the OPERA paper (http://arxiv.org/pdf/1109.4897v1).

Having said that, as other replies have noted, this kind of correction is well-understood, so while it isn't explicitly laid out as far as I can tell, it's unlikely the OPERA group screwed this up. What may well be true, though, is that there may be systemic offsets either in the GPS timing system, the implementation at Gran Sasso (they actually have a big waveguide that they run from the Earth's surface all the way to the GPS reveivers they have by their detector deep underground), or any of the myriad corrections that were needed to determine the time-of-flight baseline (although as far as I can tell they worked very hard to get this measurement right...).

It's also rather suggestive that the author of this paper has no particle physics (or even physics) credentials. So he/she probably doesn't know the OPERA collaboration's processes very well (admittedly, these details should be in the paper, but the tradition of the community is to not do that sort of detail in announcement papers like this...)

Re:Having Read Both Papers (1)

cloricus (691063) | more than 2 years ago | (#37727514)

The summary uses the word 'infamous' to describe the original announcement. In my mind it could only be considered infamous if they made a simple and blatant error. As it looks to a layman they have made an error but in finding the error physics will gain some interesting knowledge it didn't have before. If the latter is true then I'd imagine this would be remembered for all the right reasons not all the wrong ones.

Would this be the case or is the physics world full of jerks?

Re:Having Read Both Papers (1)

CharlyFoxtrot (1607527) | more than 2 years ago | (#37727702)

No no no, in-famous is when you're MORE than famous. This announcement is not just famous, it's IN-famous.

Whats... (-1)

Anonymous Coward | more than 2 years ago | (#37726726)

this I hear about occupy Wallstreet?

Re:Whats... (-1)

Anonymous Coward | more than 2 years ago | (#37726782)

It's about a bunch of middle class kids that think they have it so rough even though they don't know what oppression really is.

Re:Whats... (0)

Dunbal (464142) | more than 2 years ago | (#37726850)

Oppression is whatever you want it to be, or whatever you say it is. Welcome to politics.

Re:Whats... (-1)

Anonymous Coward | more than 2 years ago | (#37726946)

There are examples of real oppression all over, they are hoping we don't get to that point in this country. I hope we don't get there as well.

Re:Whats... (0)

AngryDeuce (2205124) | more than 2 years ago | (#37726996)

Oppression is relative. In a country with freedom of speech, censorship would (and should) be considered oppressive. I guess what I don't understand about those comments is why it's okay to tell a bunch of protesters they should just be happy with what they have when things could be worse...but for some reason telling the wealthy they should be happy with less is just so wrong. Why can't the Koch's be happy with a couple million bucks a year, for instance? I bet you could literally halve their fortune right now and their lifestyle would barely be effected, if at all. Meanwhile, start axing middle class state worker pay and benefits left and right like they're doing here in Wisconsin, and when they balk, it's because of all the "entitlements" and how greedy they are?

Speaking of "entitlements": Do the ultrarich not feel they are entitled to their vast wealth? Do they not feel they are entitled to police protection, or access to a hospital, or clean drinking water, or any of the other things that we have? But a bunch of people saying they're entitled to job security and a living wage is just crazy talk from a bunch of "socialists"?

Re:Whats... (1)

shentino (1139071) | more than 2 years ago | (#37727392)

You aren't going to make everyone happy unless you run the government on unicorn farts instead of real money.

Someone has to foot the bill for a government that keeps it rule of law instead of rule of strongest mob with the fastest trigger fingers.

I hope that this is true. (0)

barfy (256323) | more than 2 years ago | (#37726772)

My theory maximum speed would be 2C. This would allow contemporaneous or slower information exchange at distance without causality paradox (you never get there faster than "now", and you wouldn't be able to pass information previous to now, and you couldn't pass the others information back in time as well). But it does mean that you would have wicked low latency between like here and say mars when playing doom. Or even from other stars... (you both have to invent the same device, and then be able to communicate and understand each other).

You also have this very interesting possibility of neutrinos packed with information all hitting the big bang at the same time. Possibly CAUSING the big bang. I am hoping!

Re:I hope that this is true. (0, Troll)

muon-catalyzed (2483394) | more than 2 years ago | (#37726856)

This whole story is nonsense. FTL? How much faster? 10000x 10x ? They measured the actual difference is like 1.00001x faster, so this is of total insignificance, a nuance, measurement error most likely, relativity itself might explain the negligible difference. This is not even news worthy and would have zero impact even if proven true.

Re:I hope that this is true. (1)

MichaelSmith (789609) | more than 2 years ago | (#37726942)

Say you could cool those FTL neutrinos so that traveled much faster than light. They would be a lot more use then.

Re:I hope that this is true. (1)

icannotthinkofaname (1480543) | more than 2 years ago | (#37727124)

They measured the actual difference is like 1.00001x faster, so this is of total insignificance

You're wrong. The error bars on experimental data are a statistical thing. By the very fact that their margins of error didn't allow their confidence intervals to capture the speed of light, the speeds of the neutrinos were statistically significant in their difference from (in this case, above) c for some significance level. I don't know what their level was, but it was probably .1, .05, or tighter, since these are pretty standard significance levels. That means that if all their instruments were calibrated perfectly and their calculations were all correct, there's a 90-95% chance (if the significance level is .1 or .05) that the actual speed of the neutrinos was really within the confidence interval (and so were that much faster than c).

Unless you have a different definition of significance, in which case, you should be more specific.

Re:I hope that this is true. (2)

Xaositecte (897197) | more than 2 years ago | (#37727182)

The reason the speed of light is an unbreakable barrier is because it would take theoretically infinite energy to accelerate anything past the speed of light. It's the place in the equation where the equations break down into infinity, and we can't predict exactly what's going on.

If there's evidence that the speed of light isn't an absolute barrier, it means our current understanding of relativity is wrong.

Re:I hope that this is true. (1)

Bill Currie (487) | more than 2 years ago | (#37727278)

If there's evidence that the speed of light isn't an absolute barrier, it means our current understanding of relativity is wrong.

Not necessarily wrong, just missing some details. If our current understanding was wrong, we would have already seen all sorts of phenomena that don't fit the theory.

Re:I hope that this is true. (1)

CharlyFoxtrot (1607527) | more than 2 years ago | (#37727788)

Exactly, like Newtonian physics wasn't "wrong" at the time because it explained what people could observe but couldn't explain everything we could see once we could look further into space. Maybe this is us looking further.

Re:I hope that this is true. (0)

Anonymous Coward | more than 2 years ago | (#37726874)

Uh, come back when you can express your theory coherently.

2C != wicked low latency to mars, really -- it sounds as though you think neutrinos teleport instantly (in what reference frame? Oh, that's right, you don't say), while other particles are slower (all particles? Some particles?) at 2c, but I really can't tell. And not a word about the modifIcations to special relativity to make it work out, I see, much less to explain how GPS etc. are all consistent with Einstein's SR -- unless your theory can be shown to asymptotically match it, with good quantitative agreement to 0.5c or so, it's already experimentally disproven.

Re:I hope that this is true. (1)

bondsbw (888959) | more than 2 years ago | (#37726914)

Well, if one particle goes one direction at near C, and another particle goes the opposite direction at near C, then the they are traveling apart at nearly 2C (relative to the original frame, that is). IANAP, but that's how I understand it.

That could help your lag, because you could position an intermediate server between Earth and Mars serving as the host. Then it would only be a minimum of 1 minute 33 seconds lag, perfectly acceptable for a 1993 game of Doom. :)

Re:I hope that this is true. (2)

geekoid (135745) | more than 2 years ago | (#37726928)

Both would be going C by any point of reference.

Re:I hope that this is true. (1)

bondsbw (888959) | more than 2 years ago | (#37727134)

I don't think so. If a particle is traveling away from me at 185K miles per second, after 1000 seconds, it will be a distance of 185M miles. If another particle is traveling the opposite direction at the same velocity, after 1000 seconds it will be a distance of 185M miles. (All distance/time measurements in my frame.)

So in my frame, they will be 370M miles apart after 1000 seconds, and having started 0 miles apart, the delta-T is 370K mi/sec. Which is nearly 2C (372K mi/sec).

The only way to say their separation speed is less than 2C in my frame is to admit that either their distance is less than 186M miles apart after 1000 sec (in my frame), or that my measurement of time is incorrect in my own reference frame.

Re:I hope that this is true. (1)

bondsbw (888959) | more than 2 years ago | (#37727214)

And to be clear, I understand the concepts of time dilation and length contraction. So I'm still acknowledging that each of those particles will, in their own frame, see the other particle leaving at a speed of less than C. They will see the distance between themselves as less than the distance I see between the two.

And this doesn't account for the time light travels back to me. That has to be accounted for and calculated as I receive the information back. It also doesn't speak for relativity of simultaneity... events from both particles that appear simultaneous with me will not appear simultaneous to each other, even accounting for the speed of information travel.

Re:I hope that this is true. (1)

PhunkySchtuff (208108) | more than 2 years ago | (#37727586)

You don't seem to understand relativity. It's perfectly possible for the scenario you describe to happen. You shine two torches away from each other, the photons from each torch are moving at c.

Whilst the distance between them grows at a greater rate than the distance between you and either one of the photons, there's nothing special going on here. You don't see anything moving faster than c

Re:I hope that this is true. (1)

bondsbw (888959) | more than 2 years ago | (#37727874)

I don't get the point of your post, or why you claim I don't understand relativity. I never claimed that anything would actually travel FTL, or that I have made some huge discovery.

You even confirmed what I did say, that it is possible to observe separation speeds of at-or-near 2C without violating relativity or the principle of invariant light speed. My post was a response to a post that assumed that I was talking about the speed of any single particle relative to another point in space... which isn't true, I was talking about separation speed of two particles in two different frames observed by a third frame.

Re:I hope that this is true. (1)

PhunkySchtuff (208108) | more than 2 years ago | (#37727902)

No worries then - what you say is completely correct then, you can observe the distance between two particles increasing at 2c. Somewhere in the conversation thread, I thought someone was saying that this would equate to a speed of 2c.

Re:I hope that this is true. (1)

MichaelSmith (789609) | more than 2 years ago | (#37726934)

IIRC quantum mechanics breaks causality anyway. Interactions between coupled particles have been shown to occur instantaneously, ie, faster than light.

Re:I hope that this is true. (2)

Goaway (82658) | more than 2 years ago | (#37726968)

No information can be transmitted, so causality is not violated.

Re:I hope that this is true. (1)

bondsbw (888959) | more than 2 years ago | (#37727490)

If Alice and Bob are one light-minute apart, and they both agree to measure the state of entangled particles, and agree that Bob sends Alice his measurement immediately. Alice predicts the value Bob will send, a minute prior to receiving it, which means she knew it in the past according to the principal of causality.

Well... that's how I understand it. But this is an area that I really don't get very well... my interpretation is probably fundamentally wrong somewhere. I know that Alice couldn't send any new information. So it seems that causality wouldn't necessarily be broken, but that one could now predict certain forms of information obtained by quantum entanglement at faster-than-light speeds.

Re:I hope that this is true. (2)

Goaway (82658) | more than 2 years ago | (#37727536)

That situation violates causality only for some definition of causality which is not useful.

What matters in causality is avoiding paradoxes. You cannot create a paradox using quantum entanglement, thus there is no problem.

Re:I hope that this is true. (1)

bondsbw (888959) | more than 2 years ago | (#37727836)

Ok, but even if Alice and Bob found a way to transmit new information instantly, I'm still not seeing how a paradox could exist. Alice could send Bob a message, and Bob could calculate a response and send it back. Alice would receive the calculated response before light-speed would allow, but that wouldn't seem to violate causality by creating a paradox... from what I can tell, it would only violate the principle that nothing could travel faster than the speed of light. But instantaneous information transfer (FTL) is the supposition, therefore nothing has been proven.

I'm not trying to be difficult... seriously, just trying to get how some of these concepts aren't just circular definitions.

Re:I hope that this is true. (1)

Goaway (82658) | more than 2 years ago | (#37727864)

The reason it seems unproblematic is that you think about the problem in regular Euclidean space. However, our universe is not Euclidean, it is (ignoring general relativity) Minkowski space. In Minkowski space, the ordering of events in spacetime is much harder to pin down. Sending a signal "faster than light" allows you to send signals back through time, causing paradoxes.

Try finding a good introduction to special relativity, it should have some thought experiments to further demonstrate how this works.

Re:I hope that this is true. (1)

tftp (111690) | more than 2 years ago | (#37727614)

Alice predicts the value Bob will send, a minute prior to receiving it

Bob is superfluous here; he is not sending anything that Alice doesn't know. Alice can flip a coin and write the outcome down. Then she copies it on a Post-It note and sticks it to the monitor. Then she looks at it a minute later, compares with the earlier record and finds that they are identical. This only means that she sent the information into the future, which is not very unusual.

Garbage (5, Insightful)

Goaway (82658) | more than 2 years ago | (#37726776)

This is another easy-to-digest paper written by someone who doesn't have the first clue about what was actually done in the experiment, trying to explain it with undergrad physics. And the press jumps on each and every one of these, no matter how bad they are.

In this case, GPS clock synchronization to nanosecond levels is regularly done in meteorology, the relativistic effects are well known and compensated for, because it wouldn't work at all if they weren't, and the synchronization was confirmed by a non-GPS method.

Absolutely nothing to see here.

Re:Garbage (2, Interesting)

Windcatcher (566458) | more than 2 years ago | (#37726834)

I won't call it "garbage", but otherwise I was thinking along similar lines (disclaimer -- I have a Master's in Physics but I haven't bothered to do the math). 60ns is an eternity in an experimental setup, and while the two sites are at different latitudes (and a straight-line three-space trajectory sends the neutrinos along a curved path in spacetime), I can't see earth's relatively weak gravity accounting for such a discrepancy. It's a curved 4-space path, but it's not *that* curved.

Re:Garbage (1, Offtopic)

thygate (1590197) | more than 2 years ago | (#37727074)

I have a mint-in-the-box signed wesley crusher action figure for sale, also getting rid of my lightsaber collection, interested ?

Re:Garbage (1)

Ironhandx (1762146) | more than 2 years ago | (#37727888)

Its complete garbage.

In order for their experiment to succeed they needed extreme target accuracy, to within 1 meter. This requires they be off by 20 metres. The fact that their experiment succeeded at all for their original purpose kills this bullshit right off.

Re:Garbage (1)

History's Coming To (1059484) | more than 2 years ago | (#37726854)

Agreed. If this problem existed then the GPS and satnav industries wouldn't exist because it wouldn't work.

Re:Garbage (0)

JoshuaZ (1134087) | more than 2 years ago | (#37727242)

Not really. The GPS system and satnav systems take SR and GR into account automatically for working out locations. They don't automatically work out the precise timing. So if one is using GPS for timing one can't just rely on the standard GPS software and calculations for timing.

Re:Garbage (2)

tftp (111690) | more than 2 years ago | (#37727646)

They don't automatically work out the precise timing. So if one is using GPS for timing one can't just rely on the standard GPS software and calculations for timing.

That must be bad news for manufacturers of GPS timing receivers [trimble.com] . As matter of fact, I was working with this very receiver, it's tiny but it tells you time with 15 ns. accuracy - it is more accurate than the error in the experiment.

But as I understand the OPERA people weren't using the GPS timing, they physically moved a synchronized clock (and compensated for the effect of moving it.)

Re:Garbage (1)

JoshuaZ (1134087) | more than 2 years ago | (#37727734)

Yes, sorry imprecise on my part. I mean they don't do precise timing that is universal. They can be used as I understand for short timing in any specific location but not for timing that is by itself correct for two different locations. Is that correct? In any event, I agree with you that it seems like this shouldn't be an issue given how OPERA was doing the timing.

Re:Garbage (1)

tftp (111690) | more than 2 years ago | (#37727822)

I mean they don't do precise timing that is universal. They can be used as I understand for short timing in any specific location but not for timing that is by itself correct for two different locations. Is that correct?

I'm not quite sure how to approach this. First of all, we must ignore the large relativistic effects because then the notion of common timing becomes moot (What time is now at Proxima Centauri? Well, it depends on how fast you fly the clock there.)

Once we constrain ourselves to Earth, GPS indeed provides correct time for a specific location ... any specific location. Since there is no limit on the number of GPS receivers, you can have two receivers at two locations and they will be all providing the correct time - or, shall we say, the same local time.

Give the researcher some credit (1)

werepants (1912634) | more than 2 years ago | (#37726794)

I think it's fair to assume that the researcher would read the original paper before publishing a reaction to it, and so we can assume that this is something they didn't already cover in their initial analysis.

Relativity is tricky business, though, so it wouldn't be hard to forget to take something into account. Mass distribution between the two sites, for instance, will cause tiny changes in spacetime, which is certainly not a trivial thing to compute. Hopefully this paper and more like it will help us figure out what is really going on, although we probably won't really be able to put the matter to rest until we get some info from the repeat experiment at Fermilab.

Re:Give the researcher some credit (3, Insightful)

Goaway (82658) | more than 2 years ago | (#37726800)

I think it's fair to assume that the researcher would read the original paper before publishing a reaction to it,

The original paper does not go into detail about the procedures, because it beyond the scope of the paper. You are supposed to go look these things up for yourself, and the person who wrote this paper very clearly didn't.

Re:Give the researcher some credit (1)

werepants (1912634) | more than 2 years ago | (#37727222)

The original paper does not go into detail about the procedures, because it beyond the scope of the paper. You are supposed to go look these things up for yourself, and the person who wrote this paper very clearly didn't.

Ok, to be fair I haven't read either paper. Apparently I overestimate the judgment of people who publish physics papers (on arXiv, anyway).

Re:Give the researcher some credit (1)

Goaway (82658) | more than 2 years ago | (#37727500)

The "on arXiv" part is pretty crucial. Papers there should not be taken seriously unless there is a compelling reason to trust the author.

Gut feeling (0)

msobkow (48369) | more than 2 years ago | (#37726804)

My gut feeling is that Einstein's "law" of relativity won't hold up throughout the universe. I suspect that some "constants" aren't as constant as we think they are, and may vary at different points in the universe.

I have absolutely no physics or math to back that instinct up.

Re:Gut feeling (-1)

Anonymous Coward | more than 2 years ago | (#37726848)

Well, placing money on Einstein's relativity holding up over the long haul would be a foolish bet.

Humanity currently understands the following about the nature of existence: Jack and shit.

Scientists are cognizant of this; that's why relativity is a scientific theory, not a scientific law.

Re:Gut feeling (5, Insightful)

bmo (77928) | more than 2 years ago | (#37726910)

>we know jack and shit

This attitude is not helpful. This is part of the reason why biblical literalists get away with what they do. They say "hurp, we don't know anything at all, so you may as well believe Genesis word-for-word."

It is anti-reason and a cop-out.

And you cap it off with a complete misunderstanding about what a theory is.

Your post is a load of manure, sir.

--
BMO

Re:Gut feeling (1)

spottedkangaroo (451692) | more than 2 years ago | (#37727890)

There are projects looking for changes in the constants, cosmologically speaking. It's not something they haven't thought about, it's just really hard to detect. Nobody knows if this is the case and it's surely not ruled out, nor assumed to be constant everywhere, but it surely seems to be everywhere local to us.

Could this be quantum weak measurement? (5, Funny)

Dr. Spork (142693) | more than 2 years ago | (#37726832)

In case you wondered this, check out what could be the world's greatest article abstract: Can apparent superluminal neutrino speeds be explained as a quantum weak measurement? [arxiv.org]

Seriously, it's worth clicking, and understanding the abstract doesn't require advanced physics knowledge.

Re:Could this be quantum weak measurement? (0)

Anonymous Coward | more than 2 years ago | (#37726970)

That is, indeed, one of the most clearly written and effective article abstracts I've ever seen. Thanks for bringing it to my attention.

Re:Could this be quantum weak measurement? (1)

ColdWetDog (752185) | more than 2 years ago | (#37727208)

Seriously, it's worth clicking, and understanding the abstract doesn't require advanced physics knowledge.

Best. Abstract. Ever.

Earth's rotation (1)

Pollardito (781263) | more than 2 years ago | (#37726948)

My money is on the fact that the true path of the beam was not from one city to the other, but from the spot where one city was when it started to where the other city was when it stopped. If the path was opposite the rotation of the earth, that'd be very slightly shorter right? Earth doesn't spin fast compared to the speed of light, but this error wasn't very large either

Re:Earth's rotation (1)

tftp (111690) | more than 2 years ago | (#37727766)

Earth is not just rotating around its axis. Earth is also rotating around the Sun, and the Sun moves on its orbit within the Galaxy, etc. etc.

Earth's orbital speed is about 30 km/s. The test distance is 730 km. Neutrinos traveled the same path in 2.4 ms. Earth during this time moved by 30 km/s * 2.4 ms = 72 meters. Since the neutrino was emitted at the speed of light, even though the source was receding, it can be interpreted as if the receiver was closer to the source than anticipated.

If the Earth's vector is not lined up with the test path then the excess time will be varying from the -150 ns to +150 ns.

This wouldn't be a problem in classical mechanics because the speed of the neutrino would be less than c and both deltas would take each other out. But since I'm not a physicist I will stop right here :-)

If neutrino were faster than light... (2)

drobety (2429764) | more than 2 years ago | (#37726986)

If neutrinos were faster than c, the neutrinos from SN1987A would have arrived "five years sooner," [newscientist.com] while they were measured arriving "3 hours before the dying star's light caught up" as expected...

Re:If neutrino were faster than light... (1)

MichaelSmith (789609) | more than 2 years ago | (#37727044)

Damn. Good point.

Re:If neutrino were faster than light... (1)

MichaelSmith (789609) | more than 2 years ago | (#37727082)

But then the article doesn't say if anybody was looking five years before the supernova, or if there has been any attempt to find a pulse of neutrinos that early.

Re:If neutrino were faster than light... (0)

Anonymous Coward | more than 2 years ago | (#37727160)

This argument again.
Not all neutrinos travel at the same speed.

Re:If neutrino were faster than light... (0)

Anonymous Coward | more than 2 years ago | (#37728032)

The paper itself mentioned this IIRC. The experiment used a very different (higher) energy level. I don't believe they're going FTL, but you can't dismiss the result just by refering to the supernova measurements.

The named papers wrong (1)

physburn (1095481) | more than 2 years ago | (#37726988)

Sorry, but the suggesting that CERN and OPERA clocks are the GPS satellites and adjusting for there speed is just wrong. CERN and OPERA used GPS for accurate geophysics and timing measurement but have they own synchronized clocks in the earths frame. The fasting than light measurement isn't going to go away that easily.

My personnel solution is that neutrinos feel a fifth force (many at low energy), and this fifth force as left a enough binding energy for the Scarnhorst effect to increase the speed of there force carrier above the speed of light. see axitronics [blogspot.com] for details.

bogus (5, Interesting)

bcrowell (177657) | more than 2 years ago | (#37726994)

It's bogus. (Yes, I am a physicist.) OPERA used portable atomic clocks, which were moved to the the two labs and then synchronized via GPS (see this article [nature.com] ). GPS thoroughly incorporates general relativity (which includes special relativity). It has incorporated GR ever since it was first built, because if it didn't, it wouldn't work. At all. No, not even well enough for hiking and driving. Here [livingreviews.org] is a review article on relativity in GPS. GPS uses coordinates called Earth-Centered Inertial (ECI). These are coordinates (t,r,theta,phi), where the spatial coordinates are spherical coordinates that rotate along with the earth, and t is the time coordinate of a hypothetical observer in a nonrotating frame at rest relative to the center of the earth. General relativity is completely agnostic about what coordinate system you use, so this choice of a coordinate system is not a choice that has any physical significance; it's just a bookkeeping thing. Van Elburg assumes that GPS was constructed by people who didn't understand relativity, and therefore GPS times need to be corrected for relativistic effects. That's just completely wrong.

Roud trip time is what counts. (1)

Kaenneth (82978) | more than 2 years ago | (#37727340)

Any possible way to setup this experiment as a round-trip, so that only one clock matters?

Re:Roud trip time is what counts. (0)

Anonymous Coward | more than 2 years ago | (#37727388)

Actually I'd love to see the Michelson-Morley experiment repeated with neutrinos. Maybe there is an ether, it's just very very thin.

Reference Frame! (0)

Anonymous Coward | more than 2 years ago | (#37727444)

The Physists delved into the GPS reference frame at these small scales of measure.

The result is a difference of 4 ns.

Meaning, had the OPERA scientists taken into accout the rotation of the "Firing" point relative to the "Target" point, relative to the change of position of the reference frame (Global Positioning System), they would have found a descinpency of 4 ns, i.e. a result well within error ... i.e. not real.

It's over.

--

The very first thing that popped in my head (1)

modmans2ndcoming (929661) | more than 2 years ago | (#37727544)

The first thing that I thought of when they announced the FTL Neutrinos was that they did not take into account the relativistic motion in their measurements.

Measure the speed of light from CERN to OPERA (0)

Anonymous Coward | more than 2 years ago | (#37727556)

As a control experiment, use the exact same timing method to measure the speed of a radio wave or laser pulse across this distance, taking into account the index of refraction of the atmosphere. That should indicate any systematic errors in the measurement technique.

Best joke so far (4, Funny)

Anonymous Coward | more than 2 years ago | (#37727600)

"We don't serve faster than light neutrinos here", said the bartender. A neutrino walked into a bar.

What about the Tunnel? (1)

rudy_wayne (414635) | more than 2 years ago | (#37727624)

About 3 weeks ago there was this story http://science.slashdot.org/story/11/09/25/223216/the-mythical-tunnel-between-cern-and-central-italy [slashdot.org] "> where everyone laughed at the Italian minister of Public Education and Scientific Research who issued a press release which congratulated the scientists and mentioned that Italy had funded the construction of a "tunnel between the CERN [in Geneva] and Gran Sasso [the labs in Central Italy]".

But according to this new article: "scientists created neutrinos at CERN in Geneva, and then measured how long it took them to reach a detector called OPERA, located in Italy". So what's the deal? How did those neutrinos, regardless of their speed, travel the 900 km from CERN to Italy?

Re:What about the Tunnel? (1)

MimeticLie (1866406) | more than 2 years ago | (#37727712)

Are you being serious? Neutrinos travel through "solid" matter easily. There's no need for a tunnel, the particles are capable of traveling through the earth.

I could understand not knowing that the first time the story came up, but it's been awhile now. And if it was intended as a joke, it's gotten stale at this point.

Re:What about the Tunnel? (3, Informative)

nedlohs (1335013) | more than 2 years ago | (#37727820)

Through the ground.

Just like you don't need to remove the air in a "tunnel" between point A and point B to send a beam of light between them, you don't need to remove the rock in a "tunnel" between point A and point B to send a beam of neutrinos between then. Of course enough air will block the light as and several hundred light years of solid rock would block the neutrinos. 900km of rock however is not going to do anything, digging a tunnel would make no difference at all.

Another hypothesis (1)

Anonymous Coward | more than 2 years ago | (#37727636)

I am a particle physicist. The pulse is gigantic compared to the time difference they're claiming. If there's even a tiny difference in pion production efficiency between the leading and lagging edges of each proton bunch (or, say, a difference in K-to-pi ratio), and that difference isn't properly modelled by the Monte Carlo, it will create a significant bias in the timing, which is calculated statistically. You can never know, for any neutrino, where in the bunch the progenitor proton lay, so if ones toward the front are slightly more neutrinos, it will make the group seem faster.

LIGHT WILL REDEEM YOU!!! (1)

ruberg_nadnerb (2027628) | more than 2 years ago | (#37727664)

I don't understand why they don't just shoot photons down the link to see if it is equivalent to the speed of light. Any uncompensated time dilation factors should immediately be recognized. Seems like the easiest route to disprove these time dilationists.

Do GPS measurements even matter? (0)

Anonymous Coward | more than 2 years ago | (#37727886)

When I first read about the CERN experiment, they mentioned that neutrinos were arriving faster then photons-- i.e., they repeated the timing measures with light, or had photons in the original experiment. Even if the GPS coords were off, the experiment stil has something moving faster then light in a vacuum.

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