[Herra Tohtori]

Stop right there, neutrino scum! Nobody breaks the superluminal barrier on my watch! Pay the CERN a fine or serve your sentence! Your stolen time is now forfeit.

Nature

Science

BBC

The experiment is called OPERA (Oscillation Project with Emulsion-tRacking Apparatus), and lies 1,400 metres underground in the Gran Sasso National Laboratory in Italy. It is designed to study a beam of neutrinos coming from CERN, Europe's premier high-energy physics laboratory located 730 kilometres away near Geneva, Switzerland. Neutrinos are fundamental particles that are electrically neutral, rarely interact with other matter, and have a vanishingly small mass. But they are all around us — the Sun produces so many neutrinos as a by-product of nuclear reactions that many billions pass through your eye every second.

The 1,800-tonne OPERA detector is a complex array of electronics and photographic emulsion plates, but the new result is simple — the neutrinos are arriving 60 nanoseconds faster than the speed of light allows. "We are shocked," says Antonio Ereditato, a physicist at the University of Bern in Switzerland and OPERA's spokesman.

Ok, this result puzzles me. Why would neutrinos go faster than light but still stay that close to the value of c? Why wouldn't they go faster? Why would the neutrinos travel at constant speed as opposed to different neutrinos going at different speeds?

How would neutrino oscillations affect neutrinos at superluminal speeds?

If neutrinos have mass, does it mean they never travel at subluminal speeds?

Are they tachyons?

Do they break causality? (short and easy answer - no)

How the hell do these guys reliably detect the transmitted neutrinos when they regularly travel through matter without so much as a single interaction? There's +700 km of stone between the two locations, what makes their instruments capable of reliably detecting the neutrino stream...?

Could this system be used in communication through the Earth (problem: Transmission station requires a particle accelerator and receiver apparatus likely also has huge mass just to ensure reception of a few neutrinos of the beam, and would likely be prone to noise from other neutrinos passing through).

Interesting questions, and I'm eagerly expecting the answers...


However, I suspect there is a systematic error of some kind in the experiment that they just haven't figured out yet. Specifically I would think the error is related to problems in ensuring simultaneity between two locations. How do they ensure that the time measurement between transmission and reception are accurate? Not knowing any details of the experimental set up, can't say anything about that.


Regardless, this is most intriguing and I hope that the light barrier proves not to be the unbreakable ideal it has been assumed to be.

[Dragon]

60 nanoseconds? That can't be right, it's an enormous amount of time in these scales. For now, I'd assume some error in the experiment itself. But if it's not an error, then what? Perhaps gravity is the cause (if there was something in the Earth core that would "compress" space much more than we assume, then perhaps this could influence neutrinos), or maybe FTL is really possible? For sure, this is very interesting.

[headdie]

My first assumption would be a timing or computer sync issue, but they said they stated

"We wanted to find a mistake - trivial mistakes, more complicated mistakes, or nasty effects - and we didn't," he told BBC News.

so I assume that they have been accounted for, the only possibility that I can think of that dosn't involve breaking c is that the experiment was looking for something unrelated so there might be an error they cant detect.  It would be interesting to see if someone can repeat the results in a dedicated experiment.

[Dragon]

The problem with neutrinos is that there aren't many other ways to do anything with them than the way OPERA works. These things were first "invented" as a way to explain missing mass in radioactive decay (IIRC) and not actually found until much later. They're almost completely intangible, weak nuclear force is, unfortunately, quite weak, so is (in these scales) gravity, with the added difficulty of it having infinite range and coming from every single thing in the universe. In short, measuring anything regarding neutrinos is extremally difficult compared to other particles.

[G0atmaster]

The margin for error on this test was stated at +- 10 nanoseconds.  Do Nutrinsos have mass?

[headdie]

The margin for error on this test was stated at +- 10 nanoseconds.  Do Nutrinsos have mass?

Neutrinos have a very small, but nonzero mass

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

[Herra Tohtori]

60 nanoseconds? That can't be right, it's an enormous amount of time in these scales. For now, I'd assume some error in the experiment itself. But if it's not an error, then what? Perhaps gravity is the cause (if there was something in the Earth core that would "compress" space much more than we assume, then perhaps this could influence neutrinos), or maybe FTL is really possible? For sure, this is very interesting.

I was thinking that mayhap gravity field is stronger at CERN location than on Gran Sasso, which would mean atomic clocks run faster on the recipient's end due to time dilatation (similar problem affected the GPS satellites when they were first put on orbit).

However, in an analysis of the required effect, the difference would need to be 60 nanoseconds in the time it takes for the neutrinos to get to their destination (assuming that the TRANSMIT TIME has been successfully synchronized in both locations and is accurate) - the total travel time for light would be 2,435,017.89 nanoseconds, and 2,434,957.89 for these neutrinos, or 2.435 milliseconds.


That means, for every 31,556,926 seconds that passes in a year at San Grasso, 31,557,703.596839672656537956644 seconds would pass at CERN. That's a time difference of a whopping 777.59684 seconds during a year - that's almost 13 minutes! There's no way that can be right! It would have been noticed a million times already, so I think that can be cast out of the possible reasons.


The second thing I was thinking was local variation of the fine structure constant that could vary the speed at which atomic clocks work at CERN and Gran Sasso, but again this would be something that definitely would have been noticed, and a variation of phi at such local concentration would be unprecedented (there have been speculation of FSC being a variable on cosmological scale rather than constant, but different on one location of a planet to another? No way.)

Those were the two "exotic" possibilities that came to mind first, bypassing all the myriads of systematic error resulting from the test rig itself.

Someone at Nature.com posted an interesting thing. Apparently, the speed of neutrinos is measured as 299,799,846 m/s (within rough margin of error) while speed of light is known as 299,792,458 m/s. That corresponds to velocity differential of about 7,388 m/s. Apparently at about sea level, orbital velocity around Earth would be about 7900 m/s which isn't exactly the same, but in the same ballpark of meaningful numbers.

Now that is probably just chance, but it got me thinking - maybe neutrinos travel straight, ignoring gravity (which would make them truly only affected by the weak interaction!), while the "light path" would be curved by gravity and therefore longer by a slight margin... *

Which is a concept that sort of buggers everything we know about light moving along geodesic lines in space-time, and light traveling the shortest path between two spots in space...

It would also suggest that gravity indeed is a quantum phenomenon with a gauge boson (we can call it a graviton, or Higgs' boson maybe) rather than space-time curvature being the actual cause for gravity (albeit a very useful model in macrogravity scale).


The neutrino mass speculation is based on the observation of neutrino oscillations - a habit of neutrinos that they can change into each other while traveling. A massless particle would not be capable of experiencing such changes as the time for a massless, light-speed particle would be locked and invariable in its own reference frame (life-time = 0, travelled distance = 0 from, say, photon's perspective).


Monkey wrenches

monkey wrenches everywhere

*Yes I know, Earth's gravity is weak and wouldn't curve a light beam all that much at 730 km distance at sea level - however it WOULD be slightly curved and a "straight" line between A and B would be technically a bit shorter. CBA to actually calculate how much shorter though.

[Nuke]

some ideas come to mind. propagation delays in semiconductors, floating point errors, gravitational variance, imprecise distance measurement, the list goes on and on. either something broke or they got to rewrite all the physics textbooks.

[Bobboau]

the thing that grabs my attention about this though is it has the CERN "brand name" attached to it, this is not Austin County Community Collage, this is mother effing CERN, if it's some thing simple then I would have hoped they would have figured it out within three years, but they are human so they will make mistakes every once in a while. so the easiest (and most likely) answer is 'they ****ed up' but these are people you would not expect to **** up on this scale.

also, it has been noted that light can move faster through a medium, maybe neutrinos can too? maybe they interact more than we thought, but it usually is in a harder to detect way?

[Kosh]

the thing that grabs my attention about this though is it has the CERN "brand name" attached to it, this is not Austin County Community Collage, this is mother effing CERN, if it's some thing simple then I would have hoped they would have figured it out within three years, but they are human so they will make mistakes every once in a while. so the easiest (and most likely) answer is 'they ****ed up' but these are people you would not expect to **** up on this scale.

also, it has been noted that light can move faster through a medium, maybe neutrinos can too? maybe they interact more than we thought, but it usually is in a harder to detect way?

The media does have tendencies to blow things like this way out of proportion. Unless this gets verified and repeated I'm assuming it was some kind of glitch.

[watsisname]

Oh good, I finally found the publication thanks to the BBC news link!  Thanks Herra!

http://static.arxiv.org/pdf/1109.4897.pdf

Guess I'll have to retract what I said in the other thread about them not posting the methods/data.  Looking through it now, still not convinced but it does so far look like they've covered most of the obvious angles.

[Herra Tohtori]

Light's top speed is in vacuum and all photons always travel through vacuum.

In transparent medium, photons interact with the matter they travel through and thus their apparent speed (or, the collective wavefront speed) measurably decreases while the wavefront itself still stays intact. In non-transparent mediums, the light is diffuded (the wavefront doesn't stay intact and light scatters about).

Light does not travel faster than c in medium, but particles can travel faster than the light's wavefront speed in medium, which causes Cherenkov radiation.


Like said though, I do expect it to be an error somewhere along the line, as it's the more likely explanation of the two options. However... it does pose interesting questions if it actually happens to be legit observation with no other explanation or mitigating factors.

Also, CERN is not in the habit of releasing sensationalist statements, they are very much in the frontline of hard and arduous science making. They do check things through before releasing their results.


So, what we'll need now is a dedicated test rig to specifically test neutrino speeds, preferably with longer range and with higher pulse yields.

In fact, I suggest construction of World Area Neutrino Telescope (or WANT for short). It would consist of several neutrino observatories built all over the globe and connected via simultaneity-calibrated network that keeps the instruments in the same time. This would enable us to observe neutrino pulses with a lot more information of them than before - mainly, directional analysis, as well as directly observing the speed at which a neutrino front passes through the Earth.

Screw making pitiful neutrino pulses in a particle accelerator - we can use the neutrino pulses from supernovae, with multiple observatories (minimum of four, but as much as possible would be better) we can already determine the direction of the pulse with fairly good accuracy as well as determine the time differential of the pulse hitting the instruments at different areas of Earth.


Who's with me? Shouldn't be too difficult. Just make big water tanks all over the world in the bedrock with high sensitivity flash detectors lining their inner walls.

Who knows, maybe with enough info and interferometric reconstruction of the data, we could even gauge the Sun's neutrino stream more accurately than before.

[headdie]

Light's top speed is in vacuum and all photons always travel through vacuum.

In transparent medium, photons interact with the matter they travel through and thus their apparent speed (or, the collective wavefront speed) measurably decreases while the wavefront itself still stays intact. In non-transparent mediums, the light is diffuded (the wavefront doesn't stay intact and light scatters about).

Light does not travel faster than c in medium, but particles can travel faster than the light's wavefront speed in medium, which causes Cherenkov radiation.


Like said though, I do expect it to be an error somewhere along the line, as it's the more likely explanation of the two options. However... it does pose interesting questions if it actually happens to be legit observation with no other explanation or mitigating factors.

Also, CERN is not in the habit of releasing sensationalist statements, they are very much in the frontline of hard and arduous science making. They do check things through before releasing their results.


So, what we'll need now is a dedicated test rig to specifically test neutrino speeds, preferably with longer range and with higher pulse yields.

In fact, I suggest construction of World Area Neutrino Telescope (or WANT for short). It would consist of several neutrino observatories built all over the globe and connected via simultaneity-calibrated network that keeps the instruments in the same time. This would enable us to observe neutrino pulses with a lot more information of them than before - mainly, directional analysis, as well as directly observing the speed at which a neutrino front passes through the Earth.

Screw making pitiful neutrino pulses in a particle accelerator - we can use the neutrino pulses from supernovae, with multiple observatories (minimum of four, but as much as possible would be better) we can already determine the direction of the pulse with fairly good accuracy as well as determine the time differential of the pulse hitting the instruments at different areas of Earth.


Who's with me? Shouldn't be too difficult. Just make big water tanks all over the world in the bedrock with high sensitivity flash detectors lining their inner walls.

Who knows, maybe with enough info and interferometric reconstruction of the data, we could even gauge the Sun's neutrino stream more accurately than before.

I was thinking along similar lines, but unfortunately I dont have a couple of billion in my back pocket to fund it

[Bobboau]

there might be something specific about this experiment, they were trying to figure out why neutrinos change type, maybe the specific type of neutrinos they were making or how they were making them did something, maybe it isn't a simple function of energy so even if it comes from a supernova  it wouldn't show the same effect, maybe you need to have 'fresh' neutrinos that pass through relatively dense solid matter for this effect to happen.

[MP-Ryan]

I recall reading yesterday that the group is hedging their results and practically begging others to attempt to replicate their results.  It'll be crazy if it's not an experimental design failure and actually a true result.

[Herra Tohtori]

I guess it would have been noticed if the speed of light had suddenly changed by ~7000 m/s...

[watsisname]

It would certainly have made the guy whose spends each day shooting the moon with a laser to find its distance go WTF. 

[Mika]

Rest assured CERN does **** things up. A couple of my colleagues have been working there, and based on their anecdotes, CERN has caused considerable repair bills to the nations funding it. Despite of that, they don't usually release preliminary results.

[Herra Tohtori]

Rest assured CERN does **** things up. A couple of my colleagues have been working there, and based on their anecdotes, CERN has caused considerable repair bills to the nations funding it. Despite of that, they don't usually release preliminary results.

Do you refer to the helium incident or some other stuff?

[Sushi]

I'm extremely annoyed at how badly the press has blown this out of proportion. It basically amounts to the research group saying "hey guys, our results don't make any sense. We can't figure out why, so we're opening this up to the wider community."