# Can neutrinos travel Faster Than Light **URL:** \ **Category:** Factual Questions\ **Created:** [September 22, 2011, 10:59pm UTC](https://boards.straightdope.com/t/can-neutrinos-travel-faster-than-light/597266 "2011-09-22T22:59:06Z")\ **Posts on this page:** 20\ **Page:** 9
**Author:** ![obfusciatrist](https://avatars.discourse-cdn.com/v4/letter/o/4af34b/32.png) [@obfusciatrist](https://boards.straightdope.com/u/obfusciatrist)\ **Post date:** [September 26, 2011, 10:00pm UTC](https://boards.straightdope.com/t/can-neutrinos-travel-faster-than-light/597266/161 "2011-09-26T22:00:24Z")
> [@Chronos](#): > > The in-line detector would address those objections better, though, so ideally you’d want to do both. Due to curvature, wouldn’t another detector in-line have to be tunneled pretty deep? Or could it just be in the same room but just in front of the existing detector? ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [September 26, 2011, 11:09pm UTC](https://boards.straightdope.com/t/can-neutrinos-travel-faster-than-light/597266/162 "2011-09-26T23:09:09Z")
Ideally, you’d want it to be in the same room as the _source_. The idea is that if you’re comparing times from one detector to another detector, you don’t have to worry about any effects from the source at all, and as long as the detectors are identical, the effects from the detectors will cancel out, so you don’t have to worry about those, either. But measuring from one detector to the other means you want the two detectors to be far apart. ---
**Author:** ![Terr](https://avatars.discourse-cdn.com/v4/letter/t/839c29/32.png) [@Terr](https://boards.straightdope.com/u/Terr)\ **Post date:** [September 26, 2011, 11:16pm UTC](https://boards.straightdope.com/t/can-neutrinos-travel-faster-than-light/597266/163 "2011-09-26T23:16:44Z")
> [@Chronos](#): > > Ideally, you’d want it to be in the same room as the _source_. The idea is that if you’re comparing times from one detector to another detector, you don’t have to worry about any effects from the source at all, and as long as the detectors are identical, the effects from the detectors will cancel out, so you don’t have to worry about those, either. But measuring from one detector to the other means you want the two detectors to be far apart. I wonder how long the pulse is. Since the neutrino detector, I assume, detects only a handful of neutrinos out of billions emitted, could it be that one detector would, randomly, detect some from beginning of pulse, and the other from the end of it, or vice versa? I guess if you do enough runs it will all cancel out. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [September 26, 2011, 11:38pm UTC](https://boards.straightdope.com/t/can-neutrinos-travel-faster-than-light/597266/164 "2011-09-26T23:38:40Z")
I would be absolutely gobsmacked if that weren’t one of the first things they considered and ruled out. ---
**Author:** ![Pasta](https://avatars.discourse-cdn.com/v4/letter/p/ecccb3/32.png) [@Pasta](https://boards.straightdope.com/u/Pasta)\ **Post date:** [September 27, 2011, 12:19am UTC](https://boards.straightdope.com/t/can-neutrinos-travel-faster-than-light/597266/165 "2011-09-27T00:19:02Z")
> [@Terr](#): > > I wonder how long the pulse is. 10 microseconds. > [@](#): > > Since the neutrino detector, I assume, detects only a handful of neutrinos out of billions emitted, could it be that one detector would, randomly, detect some from beginning of pulse, and the other from the end of it, or vice versa? I guess if you do enough runs it will all cancel out. This is a single-detector experiment, however the issue remains even there. In this case, they accumulated several thousand neutrino interactions in the detector to construct a time profile that has a generally square-pulse shape (but with some features). They also measured the proton beam profile at CERN, which has an equivalent shape (although I have reservations about what they have shown so far on this point). They then aligned those distributions, finding that they line up best if they introduce this 60 ns shift relative to what is expected. ---
**Author:** ![IAmError403](https://avatars.discourse-cdn.com/v4/letter/i/dec6dc/32.png) [@IAmError403](https://boards.straightdope.com/u/IAmError403)\ **Post date:** [September 27, 2011, 1:25am UTC](https://boards.straightdope.com/t/can-neutrinos-travel-faster-than-light/597266/166 "2011-09-27T01:25:25Z")
Since neutrinos pass through matter like this and travel faster than light (possibly), wouldn’t our worldwide telecommunications be improved by setting up neutrino emitters/detectors that shoot through the ground to the other side of the planet instead of bouncing data from satellite to satellite? It would also cut down on space debris. ---
**Author:** ![Ludovic](https://avatars.discourse-cdn.com/v4/letter/l/7ab992/32.png) [@Ludovic](https://boards.straightdope.com/u/Ludovic)\ **Post date:** [September 27, 2011, 1:29am UTC](https://boards.straightdope.com/t/can-neutrinos-travel-faster-than-light/597266/167 "2011-09-27T01:29:38Z")
> [@IAmError403](#): > > Since neutrinos pass through matter like this and travel faster than light (possibly), wouldn’t our worldwide telecommunications be improved by setting up neutrino emitters/detectors that shoot through the ground to the other side of the planet instead of bouncing data from satellite to satellite? That’s very true. It would be a practical application of this. Round-the-world is not quite realtime , whereas straight through is realtime for a lot more practical purposes (1/7th of a second versus 1/20th IIRC), so it would improve playability of games and two-way global conversations. ---
**Author:** ![Pasta](https://avatars.discourse-cdn.com/v4/letter/p/ecccb3/32.png) [@Pasta](https://boards.straightdope.com/u/Pasta)\ **Post date:** [September 27, 2011, 1:53am UTC](https://boards.straightdope.com/t/can-neutrinos-travel-faster-than-light/597266/168 "2011-09-27T01:53:24Z")
> [@IAmError403](#): > > Since neutrinos pass through matter like this and travel faster than light (possibly), wouldn’t our worldwide telecommunications be improved by setting up neutrino emitters/detectors that shoot through the ground to the other side of the planet instead of bouncing data from satellite to satellite? You underestimate how hard it is to make and detect neutrinos. Also, the Earth is big. Going right through the middle would reduce the neutrino flux relative to the OPERA experiment by a factor of 300, and OPERA only got one neutrino interaction every couple of hours. So, you’d be talking about a month or so between single interactions. Not exactly broadband-ready. Also, note that the last stage of the neutrino production line is a 1-km-long evacuated decay channel inside of which the neutrinos are born. This structure doesn’t lend itself to arbitrary aiming. If you only wanted point-to-point communication, you could make a kilometer (or so) deep hole in the ground. But you’d still be many orders of magnitude away from useful communication. (One way to help the numbers, at least, is to put the detector in a natural body of water. You can instrument a very large volume of water for not too much money, and more volume means a higher interaction rate. But, you will still be tied to point-to-point communication, and you will still need to amp up your beamline by several orders of magnitude beyond what we know how to do right now just to become competitive with a 2400 baud modem.) ---
**Author:** ![IAmError403](https://avatars.discourse-cdn.com/v4/letter/i/dec6dc/32.png) [@IAmError403](https://boards.straightdope.com/u/IAmError403)\ **Post date:** [September 27, 2011, 1:57am UTC](https://boards.straightdope.com/t/can-neutrinos-travel-faster-than-light/597266/169 "2011-09-27T01:57:54Z")
> [@Pasta](#): > > You underestimate how hard it is to make and detect neutrinos. Also, the Earth is big. Going right through the middle would reduce the neutrino flux relative to the OPERA experiment by a factor of 300, and OPERA only got one neutrino interaction every couple of hours. So, you’d be talking about a month or so between single interactions. Not exactly broadband-ready. > > Also, note that the last stage of the neutrino production line is a 1-km-long evacuated decay channel inside of which the neutrinos are born. This structure doesn’t lend itself to arbitrary aiming. If you only wanted point-to-point communication, you could make a kilometer (or so) deep hole in the ground. But you’d still be many orders of magnitude away from useful communication. > > (One way to help the numbers, at least, is to put the detector in a natural body of water. You can instrument a very large volume of water for not too much money, and more volume means a higher interaction rate. But, you will still be tied to point-to-point communication, and you will still need to amp up your beamline by several orders of magnitude beyond what we know how to do right now just to become competitive with a 2400 baud modem.) So you’re saying that in ten years I’ll be wearing an accurate neutrino transmitter on my wrist watch. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [September 27, 2011, 2:36am UTC](https://boards.straightdope.com/t/can-neutrinos-travel-faster-than-light/597266/170 "2011-09-27T02:36:58Z")
The factors which limit miniaturization of neutrino instruments are unrelated to the factors which limit miniaturization of electronics, and are much more fundamental. We can make electronics smaller just by figuring out ways to arrange atoms on finer and finer scales. But neutrino detectors aren’t limited by _arrangement_ of atoms, but by sheer _number_ of them. It’s conceivable, of course, that someone will come up with such a huge revolution in how we understand neutrinos that we could figure out how to detect them far more efficiently. But such a revolution would take at least a decade (and probably two or three) just to make its way through science, before anyone even started implementing technologies based on it. ---
**Author:** ![ZenBeam](https://avatars.discourse-cdn.com/v4/letter/z/3ab097/32.png) [@ZenBeam](https://boards.straightdope.com/u/ZenBeam)\ **Post date:** [September 27, 2011, 2:53am UTC](https://boards.straightdope.com/t/can-neutrinos-travel-faster-than-light/597266/171 "2011-09-27T02:53:35Z")
> [@Chronos](#): > > But such a revolution would take at least a decade (and probably two or three) just to make its way through science, before anyone even started implementing technologies based on it. And the then they’ll send the directions back to us here in the past. Duh. Really, should only take a year or two to hit the market. ---
**Author:** ![Triskadecamus](https://avatars.discourse-cdn.com/v4/letter/t/b19c9b/32.png) [@Triskadecamus](https://boards.straightdope.com/u/Triskadecamus)\ **Post date:** [September 27, 2011, 3:25am UTC](https://boards.straightdope.com/t/can-neutrinos-travel-faster-than-light/597266/172 "2011-09-27T03:25:55Z")
All this talk of tachyons that don’t interact, and have uniformly greater than c velocity leaves me with a mind image that puzzles me. Throughout time, from the big Bang to the end of the epoch of proton decay, it seems to me that some rather large number, or zero are the only possible answers to how many tachyons get produced in the universe. Since they cannot interact, without really pissing Chronos off, and they move backwards in time, and through space at greater that c, don’t they all have to arrive at the singularity, at Universal Time 0? Sorry to stick my foot in this, but I have been imagining it all day. Tris ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [September 27, 2011, 3:51am UTC](https://boards.straightdope.com/t/can-neutrinos-travel-faster-than-light/597266/173 "2011-09-27T03:51:20Z")
[Bleg] Can someone post the link where I can dload the article, for free if possible. I read the concluding paragraph and it is magnificent, science at it’s best (plus it will be famous one day…). But I lost the damn URL for that paragraph. [/Bleg] ---
**Author:** ![billfish678](https://avatars.discourse-cdn.com/v4/letter/b/7bcc69/32.png) [@billfish678](https://boards.straightdope.com/u/billfish678)\ **Post date:** [September 27, 2011, 3:52am UTC](https://boards.straightdope.com/t/can-neutrinos-travel-faster-than-light/597266/174 "2011-09-27T03:52:11Z")
> [@Triskadecamus](#): > > . Since they cannot interact, without really pissing Chronos off, and they move backwards in time, and through space at greater that c, don’t they all have to arrive at the singularity, at Universal Time 0? > > Sorry to stick my foot in this, but I have been imagining it all day. > > Tris Thats the beauty of it. All those particles from the future arriving at the exact same place at time 0 is what CAUSED the Big Bang. Its ALL that future time/space stuff that created the beginning. ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [September 27, 2011, 3:58am UTC](https://boards.straightdope.com/t/can-neutrinos-travel-faster-than-light/597266/175 "2011-09-27T03:58:38Z")
> [@billfish678](#): > > Thats the beauty of it. All those particles from the future arriving at the exact same place at time 0 is what CAUSED the Big Bang. Its ALL that future time/space stuff that created the beginning. Nice. ---
**Author:** ![billfish678](https://avatars.discourse-cdn.com/v4/letter/b/7bcc69/32.png) [@billfish678](https://boards.straightdope.com/u/billfish678)\ **Post date:** [September 27, 2011, 4:14am UTC](https://boards.straightdope.com/t/can-neutrinos-travel-faster-than-light/597266/176 "2011-09-27T04:14:09Z")
> [@Leo\_Bloom](#): > > Nice. Naw, its more a “whoah dude” puff puff “thats deep man” puff puff. But its vodka induced in this case not stuff you inhale. But it does sound scarily plausible doesn’t it? ---
**Author:** ![Askance](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/askance/32/8281_2.png) [@Askance](https://boards.straightdope.com/u/Askance)\ **Post date:** [September 27, 2011, 4:51am UTC](https://boards.straightdope.com/t/can-neutrinos-travel-faster-than-light/597266/177 "2011-09-27T04:51:35Z")
> [@Chronos](#): > > **Askance** , it was long believed that neutrinos were massless, but neutrino flavor oscillation (which has now been observed, and is pretty conclusively established) can only work if they have mass (or at the minimum, that at least two of the three varieties have mass). We know very little about what the masses are, though, beyond the fact that they’re very small: All of them are less than about 1 eV, and at least two of them are greater than about 10[sup]-5[/sup] eV. Note that, for most purposes, neutrinos having a very small mass produces experimental results that are almost the same as we would expect if they were massless. > > The same is true for photons, incidentally: A photon with very small mass would produce experimental results very similar to a truly massless photon. For any given experiment, there is some sufficiently small mass such that photons of that mass would be experimentally indistinguishable from massless ones. What this means is that we can never actually experimentally prove that photons are massless: All we can do is set upper bounds on what the mass can be. IIRC, the current upper bounds on the photon mass are somewhere in the vicinity of 10[sup]-6[/sup] eV: That is to say, we know that if they do have mass, it must be less than that. > > Neither the mass of neutrinos nor of photons could possibly account for all of the dark matter. Neutrinos are a part of it, but current measurements seem to show that they’re only a small part of it. And photons are certainly not enough to be even worth mentioning. One of my points still remains: any object with mass, no matter how small, by Einstein can never reach the"cosmic speed limit" as it would have to reach infinite mass to do so. How then can either photons or neutrinos be said to do that? ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [September 27, 2011, 5:00am UTC](https://boards.straightdope.com/t/can-neutrinos-travel-faster-than-light/597266/178 "2011-09-27T05:00:46Z")
> [@Askance](#): > > One of my points still remains: any object with mass, no matter how small, by Einstein can never reach the"cosmic speed limit" as it would have to reach infinite mass to do so. How then can either photons or neutrinos be said to do that? And if someone wouldn’t mind, a brief explanation of \*relativistic mass \*might be nice. I understood this to be the reason (a reason that I don’t understand) why sometimes photons are said to be massless, and sometimes not. ---
**Author:** ![DSeid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dseid/32/20194_2.png) [@DSeid](https://boards.straightdope.com/u/DSeid)\ **Post date:** [September 27, 2011, 5:04am UTC](https://boards.straightdope.com/t/can-neutrinos-travel-faster-than-light/597266/179 "2011-09-27T05:04:27Z")
> [@billfish678](#): > > Naw, its more a “whoah dude” puff puff “thats deep man” puff puff. > > But its vodka induced in this case not stuff you inhale. But it does sound scarily plausible doesn’t it? Well if the universe in all its time just “is” … then yeah. The end of time for a tachyon that cannot interact with normal matter would be the start of time for us. And the end of time for normal matter would be the start of time from a tachyon POV. Causation being infinitely recursive, no more problematic than infinity and no “first cause” (or having a “first cause” too) always is, really. ---
**Author:** ![Wizard\_One](https://avatars.discourse-cdn.com/v4/letter/w/6a8cbe/32.png) [@Wizard\_One](https://boards.straightdope.com/u/Wizard_One)\ **Post date:** [September 27, 2011, 5:11am UTC](https://boards.straightdope.com/t/can-neutrinos-travel-faster-than-light/597266/180 "2011-09-27T05:11:05Z")
> [@billfish678](#): > > Naw, its more a “whoah dude” puff puff “thats deep man” puff puff. > > But its vodka induced in this case not stuff you inhale. But it does sound scarily plausible doesn’t it? In other words, Dr McCoy’s gift glasses emerged intact from the Big Bang, to eventually land on Earth intact and be gifted to Jim Kirk? 😉 As probable as a mother in law visiting detector… ]😉 [Previous page](https://boards.straightdope.com/t/can-neutrinos-travel-faster-than-light/597266.md?page=8) [Next page](https://boards.straightdope.com/t/can-neutrinos-travel-faster-than-light/597266.md?page=10)