Neutrino found traveling faster than speed of light? | Hacker News Reader

Neutrino found traveling faster than speed of light?

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90 pointsicey37 comments

Reading the other bbc story on the front page, it looks like the scientists are cautious about the discovery and not claiming that they found something. They found something that may be significant or could be an error, and are looking for review.

http://news.ycombinator.com/item?id=3027056

(better article and discussion)

Those scientists with their caution, pah! They just want to keep the time-travelling deloreans to themselves ...

Could it be that the light was recorded moving that fast, but that it is somehow an illusion based on how the data was measured?

Given how much data this contradicts, measurement error is by far the most likely explanation; that's why they're releasing their data for review rather than publishing a paper.

On the other hand, they're measuring a particle that nobody else has measured before, so it could also not be measurement error. That's the interesting possibility.

I want to see where this goes.

It wasn't light, it was a stream of neutrinos.

Ha, yeah, noted. Thanks!

Aren't neutrinos everywhere? How do they know the neutrinos they measured are the same ones they fired?

Because they came precisely from the right direction?

Yeah, I was just wondering if you could filter based on wavelength or polarization, like photons. Isn't it really hard to "block" neutrinos coming from other directions though?

Really hard? It's virtually impossible. It's incredibly hard to even detect neutrinos, much less block of filter them.

If the beam is narrow enough, you'll have a larger number of detections inside the region the beam occupies while the rest of your detector will present normal activity. While you can't be sure if the neutrinos are coming or going, the odds some unknown neutrino beam source appeared in direct opposition to the one you knew about are very slim.

You can also filter by time - you create a source and expect a surge of detections shortly after. In this specific case, they saw the surge before they expected it, indicating the neutrinos traveled faster than they should.

>the odds some unknown neutrino beam source appeared in direct opposition to the one you knew about are very slim. //

Look any direction in the night sky. Do you see a star. The odds of not seeing a star in the direction you're looking are far greater than the odds that you don't have neutrinos coming from that direction.

You can't shield against neutrinos, you can't currently detect a neutrinos position at two points in spacetime. Haven't yet read the details about this if they repeated several times with the same result then it looks interesting - have you a link to their paper (to save me looking!) thanks.

My first thought was that I wonder if this might be a simple case of super-luminal group velocities or something similar.

I wondered that too. How do you track a stream of neutrinos for 454 miles?

Once you set them in motion, you pretty much expect them to continue in that direction until they hit something, which, in the case of neutrinos, is incredibly unlikely.

I agree, it is unlikely that neutrinos can travel faster than the speed of light but I don't think we can rule out the possibility that the neutrinos measured weren't the ones generated. If you assume that there can be other forces (for lack of better word) faster than the speed of light, those forces would rarely interact with the physical universe governed by the speed of light, but when they do they could conceivably generate an interference pattern that could perturb other like particles across vast distances. So theoretically if the neutrinos generated at the source interacted with some faster than light force, the result could be perturbation of neutrinos close to the detectors, making it appear that the neutrinos actually arrived earlier than expected. I'm looking into this theory as a means of explaining black holes.

Wouldn't such interactions create feedback loops that would, in turn, create a cascading generation of neutrinos?

I didn't look at the data, but the point in time the detection cuts off is also relevant - it should match the time it took the first neutrinos to arrive at the detector. If some of the original neutrinos interacted with something outside normal spacetime and that made new neutrinos appear closer to the detector, some of the original neutrinos should have arrived at the detector at the predicted time.

Anyway, this is a very interesting concept. Hope you can somehow test it.

Not CERN. Italian group. http://www.nature.com/news/2011/110922/full/news.2011.554.ht...

This headline is terribly misleading. No one is "claiming" faster-than-light neutrinos. They simply have time measurements that aren't making sense because they show the neutrinos arriving a couple billionths of a second faster than they should, and they are opening up the findings to the wider scientific community to try and explain the anomaly.

It irks me when people sensationalize things and put the wrong spin on the data. Stop it.

Wouldn't this also violate conservation of energy? A particle with any mass, traveling at the speed of light, would have infinite energy. And accelerating a particle to that speed would "push back" on the earth with infinite force, so it might also break conservation of momentum.

Whatever happened, there is one thing we can be sure about: No laws of nature were violated in this experiment.

But that's why it's interesting, because it's possible that that's exactly what happened.

By definition the laws of nature cannot be broken, only the "laws" we think nature has.

Right, so if conservation of momentum is violated, then it's not a law of nature. That would be quite a discovery!

Considering just how fundamental conservation of momentum is, that would be quite unexpected.

It's even more fundamental than conservation of energy.

The laws of nature weren't broken, but what we think the laws of nature are based on our limited observations certainly could have been.

The reason a particle would have infinite energy as it approaches the speed of light is because its mass (relativistic mass) would also approach infinite. Thus the understood reason a particle could not attain the speed of light is because most of the energy added into a particle going near the speed of light turns into relativistic mass instead of velocity.

If these neutrinos are indeed going faster than light, they clearly did not become infinitely massive.

OK, either that or it violates relativity.

Relativity does not permit particles with mass to go the speed of light. However, the math works just fine with massive particles going faster than light. Further however, the effects are quite bizarre, even if well defined. You know how your physical intuition is basically useless when it comes to understanding relativity? It's even more useless when understanding what the math says about tachyons.

One of the more approachable discussions on the topic is actually http://www.theforce.net/swtc/hyperspace.html . Yes, I am aware of the context, but the author knows what he's talking about. http://www.mssl.ucl.ac.uk/~cjs2/

My word. The star wars technical commentaries. What a blast from the past. Thanks for that.

Just to be clear, I did say "approachable". I've seen heavier duty explorations of what tachyons are like under real relativity theory, but I don't know of anything else that approachable.

The concept behind tachyons is that whilst particles can't approach the speed of light they can be faster than the speed of light and not break relativistic equations (they couldn't then slow to the speed of light either). Similarly with time reversal.

Personally I think this is cool but probably also just difficult (if not impossible) to falsify and so hasn't yet been restricted. When you apply a mathematical model it's like applying a metaphor [so meta!], it has a limit at which it breaks down but that limit isn't always obvious and sometimes at the edges things look tantalisingly like they might work.

All the laws of physics are closely interlinked. Generally, an event or situation that violates one law of physics must also violate many others as well. For example, instantaneous teleportation would violate conservation of energy (because the departure and arrival points would have different gravitational potentials), relativity (because of faster-than-light travel), and conservation of momentum (because you need to adjust your velocity to match the arrival point in order to arrive safely), among others. This doesn't mean that teleportation violates the laws of physics in three separate ways. The three violations are all different ways of looking at the same physical impossibility.

Seeing how they keep failing to find the Higgs boson, I guess they felt they had to do something to generate buzz.

I hope this is tongue in cheek as it's clear from both AP and BBC that this is not a sensationalist release. Also note that the false alarm discovery of the Higgs in CERN this year was not an official release and rather the actions of a rogue researcher.

"We have data that suggest we saw particles moving faster than light and we are showing everybody the data because we must have made a mistake, but we can't find it by ourselves after trying a lot" is pretty much sensational enough for those who can understand the implications of the unlikely possibility they measured something that really happened.

The odds are they made a mistake. But, if they didn't, the universe just got much more interesting.

Battlecruiser operational

Tachyons, here we come! Or maybe not.

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