8 ms·

This is an almost trivial application of special relativity. It was be absolutely shocking if the dozens of scientists involves in the neutrino experiment didn'

This is an almost trivial application of special relativity. It was be absolutely shocking if the dozens of scientists involves in the neutrino experiment didn't take this into account.

dhimes 15y ago
That's what I was thinking too- this may be destined to become a problem in a relativity class (perhaps a little above Modern Physics, though). But then maybe I don't fully understand the subtleties.
Udo 15y ago
I'd file this under "systematic measurement error", and the team specifically said that something like it was the most likely cause for the results. They also said that if neutrinos really were FTL, we'd have observed this effect much earlier (for example when we started measuring supernova radiation bursts). So, the article's hypothesis is a very good candidate for a real flaw in the experiment's design. The scientists probably didn't take this into account because they assumed their setup already compensated for all kinds of clock drift... I wouldn't call this an epic failure just yet, because even if this turns out to be the root cause it's a pretty standard type of mistake as far as science experiments go. That's why we have independent reviews, and that's why they are necessary.
- dhimes 15y ago
  They also said that if neutrinos really were FTL, we'd have observed this effect much earlier (for example when we started measuring supernova radiation bursts). I am seriously doubtful that these neutrinos are traveling faster than light, but I've also been skeptical of this argument since it was presented. It would be pretty hard to have observed this if they weren't looking for it because they would have to sift through old data. For example, for SN 1987A the FTL neutrino event would have preceded the visible light neutrino event by over four years. They could go through all of the old data, to be sure, but they would have to specifically have had to be looking for something which they think fundamentally is impossible in order to find something like this. So, if these events were even recorded at all, it's certainly not clear to me that they would have done this (at the time of the FTL announcement, that is- of course, they should be doing it now). it's a pretty standard type of mistake as far as science experiments go Yes, but when one makes it this far it is big news. No matter what I give props to the scientists to publicly invite the scrutiny they did. That took balls.
deleted 15y ago
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gruen 15y ago
In 1999, NASA lost a $300MM Mars probe due to a metric/imperial conversion oversight. Shocking, yes; unheard of, no.
- crocowhile 15y ago
  Reference: http://en.wikipedia.org/wiki/Mars_Climate_Orbiter#Communications_loss http://en.wikipedia.org/wiki/Mars_Climate_Orbiter#Communicat...
- Eliezer 15y ago
  But then they found the error afterward. These physicists were looking for an error, hard.
Confusion 15y ago
They obviously did take all kinds of relativistic effects into account. It's not like they forgot about relativity. It's just that they may have overlooked a higher-order effect that is usually neglected because it is so small. Something like overlooking magnetism when looking at electricity (magnetism is a relativistic effect of moving electrical charge, but since the forces involved are so small, they are easy to miss and neglect)
- mrb 15y ago
  Confusion, funny how you said weeks ago that "relativity cannot possibly be relevant in explaining the time difference" - http://news.ycombinator.com/item?id=3030735 http://news.ycombinator.com/item?id=3030735 - and you downvoted me who was suggesting a relativist effect could explain the 60ns difference (although I was wrong about which particular effect)... coughitoldyousocough ;)
  - jrockway 15y ago
    His name is Confusion...
  - drzaiusapelord 15y ago
    Maybe the dude read a few articles or had time to think. Using one's posting history as a "gotcha" because we humans aren't allowed to change our minds for some reason, seems like a really, really odd thing to do.
    - mrb 15y ago
      Yes. But it doesn't justify his insulting replies ("I will not explain why: please actually read..."). Next time he will hopefully be more polite.
  - Confusion 15y ago
    What I meant, but I agree I didn't clearly say as much, was that completely forgetting about relativity could not possibly be the answer. At the time I was slightly annoyed at the large number of lay people who implied as much (which implies the team was being a bunch of idiots, which to seems typical of the less than respectful average attitude people have towards scientists). Those people certainly didn't have subtle effects like these in mind. So I shouldn't post when I'm annoyed, because then I tend to bark at things that are not what they appear to be.
jcfrei 15y ago
my thoughts exactly - my guess is that the editor wanted to point out this potential source of an error, because his readers were likely to understand it. to me the error seems to be too trivial for an experiment of that magnitude.
drzaiusapelord 15y ago
How many of these guys are GPS satellite engineers? It sounds like they falsely assumed that the GPS system would take care of all relativistic effects and they can just use absolute time for measurement. The GPS system was not remotely designed for this level of accuracy. The issue here could really be a misconception of how well GPS works and what it was designed to do. GPS, like all technology, has a distinct difference between theory and practice and is also engineered for certain use cases. It may be that no one really thought about this stuff until now because we're talking such tiny increments of time over such large distances. Regardless, its early in the game to know whats going on, but I'd be really surprised if suddenly neutrinos were FTL and no one noticed until sometime this year. This is starting to look like another case of super-smart over-specialized eggheads making assumptions and not seeing the big picture, like when NASA/Lockheed lost the Mars Climate Orbitor over imperial to metric conversions.
- starwed 15y ago
  >This is starting to look like another case of super-smart over-specialized eggheads making assumptions and not seeing the big picture What a fucked way to spin this -- the group asked for outside help in explaining their results and finding any mistakes.
  - drzaiusapelord 15y ago
    If these guys were humble researchers unsure of their results, perhaps RUNNING TO THE MEDIA AND SCREAMING ABOUT BREAKING THE LIGHT BARRIER should have been agenda item #8484 not #1. Seriously, if you're claiming you're doing FTL, asking for outside help isn't some noble act, its pretty much required. The idea that these guys are infallible and systemic errors never happen is incredibly naive. Christ, remind me never to get between nerds and their starship Enterprise fantasies.
    - krschultz 15y ago
      Did you read the original press release?
    - 15y ago
pmjordan 15y ago
"Almost trivial"? You're vastly exaggerating. I'm pretty sure most physics graduates would get problems of special relativity as applied to rotating (i.e. accelerating) systems completely wrong, as it's usually just not taught. Yep, someone doing the experiment should have ideally spotted it, but it's already an extremely complex system, so I'm not surprised they didn't.
bermanoid 15y ago
This is an almost trivial application of special relativity. This is even less than a trivial application of special relativity, it's literally a third grade "distance = rate x time" problem: Skipping over the relativistic stuff, which is quite frankly unnecessary (or rather, it's necessary, but the CERN authors apparently already included the corrections), the only two equations of import are (re-named vars for lack of LaTeX): 1) time_baseline = dist_baseline / c 2) time_observed = dist_baseline / (c+v) where v is the speed of the satellite. In other words, if two things are moving towards each other, then you should use the combined velocity to compute the time. Duhhh... Now, the fact that the difference in these formulas turns out to almost exactly explain away the problem is certainly suggestive, I'll be honest about that. But if this was all there was to the story, it would be massively embarrassing for someone at CERN, this is the type of error I mentally ruled out immediately because these people should be way too careful to be making elementary screwups like this. This is the type of error that freshmen lose points for on a mechanics 101 test, not one that eludes dozens of physicists working around the clock for a month. So I'm skeptical here; it's not that the author of this paper is wrong (though there are credibility red flags in the paper, even beyond the fact that he's not a physicist [he's a computer guy], like the fact that he defines gamma as the inverse of the commonly used relativistic quantity, something that indicates only a passing familiarity with the field), it's that I'm not sure that the CERN guys could reasonably be assumed to have made this mistake. Then again, maybe everyone else looking over the work also assumed that they'd dotted their i's, and didn't bother checking the trivial stuff. It's certainly happened before...
- VladRussian 15y ago
  if formula using (c+v) explains the situation while we may be sure that the CERN physicists calibrated their systems using various SR formulas with "gamma" (i.e. 1/(sqrt(1-v2/c2)) ), that would be an interesting comment on SR :) [especially considering that the Michelson-Morley experiment confirming the constant and isotropic "c" - the foundation of SR - wasn't calibrated using the SR's rules following from such properties of "c"].

This is an almost trivial application of special relativity. It was be absolutely shocking if the dozens of scientists involves in the neutrino experiment didn't take this into account.

dhimes 15y ago

That's what I was thinking too- this may be destined to become a problem in a relativity class (perhaps a little above Modern Physics, though). But then maybe I don't fully understand the subtleties.

Udo 15y ago

I'd file this under "systematic measurement error", and the team specifically said that something like it was the most likely cause for the results. They also said that if neutrinos really were FTL, we'd have observed this effect much earlier (for example when we started measuring supernova radiation bursts). So, the article's hypothesis is a very good candidate for a real flaw in the experiment's design. The scientists probably didn't take this into account because they assumed their setup already compensated for all kinds of clock drift... I wouldn't call this an epic failure just yet, because even if this turns out to be the root cause it's a pretty standard type of mistake as far as science experiments go. That's why we have independent reviews, and that's why they are necessary.

dhimes 15y ago
They also said that if neutrinos really were FTL, we'd have observed this effect much earlier (for example when we started measuring supernova radiation bursts). I am seriously doubtful that these neutrinos are traveling faster than light, but I've also been skeptical of this argument since it was presented. It would be pretty hard to have observed this if they weren't looking for it because they would have to sift through old data. For example, for SN 1987A the FTL neutrino event would have preceded the visible light neutrino event by over four years. They could go through all of the old data, to be sure, but they would have to specifically have had to be looking for something which they think fundamentally is impossible in order to find something like this. So, if these events were even recorded at all, it's certainly not clear to me that they would have done this (at the time of the FTL announcement, that is- of course, they should be doing it now). it's a pretty standard type of mistake as far as science experiments go Yes, but when one makes it this far it is big news. No matter what I give props to the scientists to publicly invite the scrutiny they did. That took balls.

deleted 15y ago

[deleted]

gruen 15y ago

In 1999, NASA lost a $300MM Mars probe due to a metric/imperial conversion oversight. Shocking, yes; unheard of, no.

crocowhile 15y ago
Reference: http://en.wikipedia.org/wiki/Mars_Climate_Orbiter#Communications_loss http://en.wikipedia.org/wiki/Mars_Climate_Orbiter#Communicat...
Eliezer 15y ago
But then they found the error afterward. These physicists were looking for an error, hard.

Confusion 15y ago

They obviously did take all kinds of relativistic effects into account. It's not like they forgot about relativity. It's just that they may have overlooked a higher-order effect that is usually neglected because it is so small. Something like overlooking magnetism when looking at electricity (magnetism is a relativistic effect of moving electrical charge, but since the forces involved are so small, they are easy to miss and neglect)

mrb 15y ago
Confusion, funny how you said weeks ago that "relativity cannot possibly be relevant in explaining the time difference" - http://news.ycombinator.com/item?id=3030735 http://news.ycombinator.com/item?id=3030735 - and you downvoted me who was suggesting a relativist effect could explain the 60ns difference (although I was wrong about which particular effect)... coughitoldyousocough ;)
- jrockway 15y ago
  His name is Confusion...
- drzaiusapelord 15y ago
  Maybe the dude read a few articles or had time to think. Using one's posting history as a "gotcha" because we humans aren't allowed to change our minds for some reason, seems like a really, really odd thing to do.
  - mrb 15y ago
    Yes. But it doesn't justify his insulting replies ("I will not explain why: please actually read..."). Next time he will hopefully be more polite.
- Confusion 15y ago
  What I meant, but I agree I didn't clearly say as much, was that completely forgetting about relativity could not possibly be the answer. At the time I was slightly annoyed at the large number of lay people who implied as much (which implies the team was being a bunch of idiots, which to seems typical of the less than respectful average attitude people have towards scientists). Those people certainly didn't have subtle effects like these in mind. So I shouldn't post when I'm annoyed, because then I tend to bark at things that are not what they appear to be.

jcfrei 15y ago

my thoughts exactly - my guess is that the editor wanted to point out this potential source of an error, because his readers were likely to understand it. to me the error seems to be too trivial for an experiment of that magnitude.

drzaiusapelord 15y ago

How many of these guys are GPS satellite engineers? It sounds like they falsely assumed that the GPS system would take care of all relativistic effects and they can just use absolute time for measurement. The GPS system was not remotely designed for this level of accuracy. The issue here could really be a misconception of how well GPS works and what it was designed to do. GPS, like all technology, has a distinct difference between theory and practice and is also engineered for certain use cases. It may be that no one really thought about this stuff until now because we're talking such tiny increments of time over such large distances. Regardless, its early in the game to know whats going on, but I'd be really surprised if suddenly neutrinos were FTL and no one noticed until sometime this year. This is starting to look like another case of super-smart over-specialized eggheads making assumptions and not seeing the big picture, like when NASA/Lockheed lost the Mars Climate Orbitor over imperial to metric conversions.

starwed 15y ago
>This is starting to look like another case of super-smart over-specialized eggheads making assumptions and not seeing the big picture What a fucked way to spin this -- the group asked for outside help in explaining their results and finding any mistakes.
- drzaiusapelord 15y ago
  If these guys were humble researchers unsure of their results, perhaps RUNNING TO THE MEDIA AND SCREAMING ABOUT BREAKING THE LIGHT BARRIER should have been agenda item #8484 not #1. Seriously, if you're claiming you're doing FTL, asking for outside help isn't some noble act, its pretty much required. The idea that these guys are infallible and systemic errors never happen is incredibly naive. Christ, remind me never to get between nerds and their starship Enterprise fantasies.
  - krschultz 15y ago
    Did you read the original press release?
  - 15y ago

pmjordan 15y ago

"Almost trivial"? You're vastly exaggerating. I'm pretty sure most physics graduates would get problems of special relativity as applied to rotating (i.e. accelerating) systems completely wrong, as it's usually just not taught. Yep, someone doing the experiment should have ideally spotted it, but it's already an extremely complex system, so I'm not surprised they didn't.

bermanoid 15y ago

This is an almost trivial application of special relativity. This is even less than a trivial application of special relativity, it's literally a third grade "distance = rate x time" problem: Skipping over the relativistic stuff, which is quite frankly unnecessary (or rather, it's necessary, but the CERN authors apparently already included the corrections), the only two equations of import are (re-named vars for lack of LaTeX): 1) time_baseline = dist_baseline / c 2) time_observed = dist_baseline / (c+v) where v is the speed of the satellite. In other words, if two things are moving towards each other, then you should use the combined velocity to compute the time. Duhhh... Now, the fact that the difference in these formulas turns out to almost exactly explain away the problem is certainly suggestive, I'll be honest about that. But if this was all there was to the story, it would be massively embarrassing for someone at CERN, this is the type of error I mentally ruled out immediately because these people should be way too careful to be making elementary screwups like this. This is the type of error that freshmen lose points for on a mechanics 101 test, not one that eludes dozens of physicists working around the clock for a month. So I'm skeptical here; it's not that the author of this paper is wrong (though there are credibility red flags in the paper, even beyond the fact that he's not a physicist [he's a computer guy], like the fact that he defines gamma as the inverse of the commonly used relativistic quantity, something that indicates only a passing familiarity with the field), it's that I'm not sure that the CERN guys could reasonably be assumed to have made this mistake. Then again, maybe everyone else looking over the work also assumed that they'd dotted their i's, and didn't bother checking the trivial stuff. It's certainly happened before...

VladRussian 15y ago
if formula using (c+v) explains the situation while we may be sure that the CERN physicists calibrated their systems using various SR formulas with "gamma" (i.e. 1/(sqrt(1-v2/c2)) ), that would be an interesting comment on SR :) [especially considering that the Michelson-Morley experiment confirming the constant and isotropic "c" - the foundation of SR - wasn't calibrated using the SR's rules following from such properties of "c"].