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Chameleon-Like Behavior of Neutrino Confirmed 191

Posted by Soulskill
from the yes,-neutrinos-eat-bugs dept.
Anonymous Apcoheur writes "Scientists from CERN and INFN of the OPERA Collaboration have announced the first direct observation of a muon neutrino turning into a tau neutrino. 'The OPERA result follows seven years of preparation and over three years of beam provided by CERN. During that time, billions of billions of muon-neutrinos have been sent from CERN to Gran Sasso, taking just 2.4 milliseconds to make the trip. The rarity of neutrino oscillation, coupled with the fact that neutrinos interact very weakly with matter, makes this kind of experiment extremely subtle to conduct. ... While closing a chapter on understanding the nature of neutrinos, the observation of neutrino oscillations is strong evidence for new physics. The Standard Model of fundamental particles posits no mass for the neutrino. For them to be able to oscillate, however, they must have mass.'"
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Chameleon-Like Behavior of Neutrino Confirmed

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  • Excited! (Score:5, Insightful)

    by SpeedyDX (1014595) <speedyphoenix AT gmail DOT com> on Monday May 31, 2010 @05:57PM (#32411462)

    Reading TFS made me very excited about the potential fundamental developments in physics. Except I don't know a thing about physics, so I'm really not sure what I'm excited about. All these words like muon, tau, and neutrino have little place in my everyday life, but they sound so interesting!

    This is what the Average American must feel like when they hear stories about Web x.0 laden with the latest buzzwords on CNN. I can finally relate!

    • The significance of this discovery is that the Standard Model is wrong. The transformation of neutrinos mean they have mass, whereas the Standard Model predicts that they have no mass. Neutrinos having mass mean they interact with matter, and that they can constitute dark matter. Or something like that. This is about all I know/or think I know about the subject.

      I hope I'm alive when the Next Big Nerd figures out the Next Big Thing regarding a Theory of Everything.

      • by Entropius (188861)

        How exactly does the standard model demand that neutrinos have mass?

        The SM works just fine with massive neutrinos. After all, most of the fun stuff in the SM concerns the gauge couplings; whether or not a few fermions have mass doesn't affect the overall theory.

        Neutrinos could constitute dark matter if they had *more* mass. But we can put an upper limit on the masses of the electron, muon, and tau neutrinos, and that's not enough to account for the amount of dark matter we know is out there. Some sort of ex

  • I don't see how changing from one thing into another is "chameleon-like behavior". I have never heard of a chameleon turning into a skink, or anything else for that matter

    • Re: (Score:3, Informative)

      by dumuzi (1497471)
      I agree. In QCD quarks and gluons can undergo colour changes [wikipedia.org], this would be "chameleon-like behavior". Neutrinos on the other hand change flavour [wikipedia.org], this would be "Willy Wonka like behavior".
    • I don't see how changing from one thing into another is "chameleon-like behavior". I have never heard of a chameleon turning into a skink, or anything else for that matter

      Try combining a chameleon with a hammer or a microwave. Then you will understand the experiments analogy.

  • Just find the people from the Movie 2012 to help you figure out how to make the Neutrinos act like Microwaves, then you could totally make this experiment easy! ... seriously... did anyone else need a friend to "dumb up" the science dialog for them?

    • Just find the people from the Movie 2012 to help you figure out how to make the Neutrinos act like Microwaves, then you could totally make this experiment easy! ... seriously... did anyone else need a friend to "dumb up" the science dialog for them?

      I had the pleasure of (involuntarily) watching that piece of shit this weekend. Sadly, the liberties taken with science were the least of that movie's problems. I'd start with the terrible script, lack of editing (solid hour too long), screwed up pacing, repe

      • by snowgirl (978879)

        Compared to that, they could have said that neutrinos turn into faerie dust and I'd have been fine.

        This I at least could have understood.

        None of their scientific babbling made any sense to me until my friend's boyfriend explained what the heck they were trying to say.

  • oscillation (Score:3, Interesting)

    by Spazmania (174582) on Monday May 31, 2010 @06:05PM (#32411544) Homepage

    The Standard Model of fundamental particles posits no mass for the neutrino. For them to be able to oscillate, however, they must have mass.

    Unless oscillation is the fundamental thing and mass is just a sometimes effect of oscillation... but then IANAP.

    • Doesn't matter what we call the two things. We just know that in this case, one requires the other.
    • Basically oscillations are repeated changes with respect to time. According to general relativity massless particles move at light speed and as a consequence do not experience the passage of time. So if neutrino's were massless they'd move at light speed and wouldn't experience time and therefore wouldn't be able to oscillate into different forms.
  • How in the universe? (Score:4, Interesting)

    by MyLongNickName (822545) on Monday May 31, 2010 @06:06PM (#32411554) Journal

    How could something have mass and so weakly interact with normal matter? My understanding is that most neutrinos pass through the earth unmolested.

    (insert obligatory Catholic priest joke here).

    I's thought that neutrinos being massless made this possible.

    • by rogeriomgatto (1364629) on Monday May 31, 2010 @06:18PM (#32411686)
      That's how they managed to escape the priests... They avoid mass.
    • by pz (113803) on Monday May 31, 2010 @06:23PM (#32411738) Journal

      How could something have mass and so weakly interact with normal matter?

      Neutrinos are thought to have a very small mass. So exceedingly small that they barely interact with anything (they also have no charge, so they are even less likely to interact). But zero mass and really, really, really small but not zero mass, are two different things.

      • by BitterOak (537666) on Monday May 31, 2010 @06:49PM (#32411982)

        How could something have mass and so weakly interact with normal matter?

        Neutrinos are thought to have a very small mass. So exceedingly small that they barely interact with anything (they also have no charge, so they are even less likely to interact).

        The fact that they barely interact with anything has nothing to do with the fact that they are nearly massless. Photons are massless and they interact with anything that carries an electric charge. Electrons are much lighter than muons, but they are just as likely to interact with something. The only force that gets weaker as the mass goes down is gravity, which is by far the weakest of the fundamental forces.

        • Re: (Score:2, Interesting)

          by Nimey (114278)

          Photons also interact with gravity - stellar masses and above can cause gravitational lensing.

        • by pz (113803)

          The fact that they barely interact with anything has nothing to do with the fact that they are nearly massless. Photons are massless and they interact with anything that carries an electric charge. Electrons are much lighter than muons, but they are just as likely to interact with something. The only force that gets weaker as the mass goes down is gravity, which is by far the weakest of the fundamental forces.

          Good point, I should have been more expansive. There are definitely many more reasons that neutrinos are non-interactive.

      • I once read somewhere that the fundamental difference between something with mass and something without mass is that "at rest" (a purely theoretical state) an object with mass it would be stationary (that is to say absolute zero motion and temperature). An object without mass "at rest" would move at the speed of light. It would take an infinite amount of energy to accelerate an object with mass to the speed of light, and an infinite amount of energy to decelerate an object without mass to absolute zero.

        I
    • by hoytak (1148181) on Monday May 31, 2010 @06:31PM (#32411824) Homepage

      Neutrinos only interact through the weak forces, which require them to be extremely close to other particles with which they interact. Such interactions also require the neutrino to have a lot of energy, since the force-carrying particles are quite massive. This is why all these experiments use neutrinos generated by very energetic reactions (accelerators, the sun, cosmic rays, etc.).

      When I worked with BooNE, an experiment researching neutrino osculations, our detector was a 40 ft tank lined filled with clear, food-grade mineral oil and lined with photo tubes capable of detecting a few photons. The neutrinos were generated by bursts of protons crashing into a special block (I don't remember the material), and the byproducts at the given energy levels would be one type of neutrino. The interactions from different types of neutrinos would have different decays, which produced different signature rings of photons on the walls of the detector. In generating 10^9 + neutrinos, we only expected a handful of interactions.

      Gravity is also on the table, but it's impossible to measure neutrinos based on that.

    • by dimeglio (456244)

      Photons are also massless and also interact with matter. Photons/electrons are also waves/particles which make them rather interesting. There might be different types of neutrinos. Some with mass, other with none. Since neutrinos are the results of a proton collision, the opposite - recreating a proton with a neutrino/strange quark collision might also explain this "mass-like" behaviour. Interesting nonetheless.

    • by BitterOak (537666)

      How could something have mass and so weakly interact with normal matter? My understanding is that most neutrinos pass through the earth unmolested.

      (insert obligatory Catholic priest joke here).

      I's thought that neutrinos being massless made this possible.

      I'm not sure why this was modded flamebait (is a reference to our propensity to joke about the Catholic church flamebait?), but to answer the question, being massless has nothing to do with a particle's ability to interact weakly. Quarks can interact weakly (as well as strongly and electromagnetically) and they certainly have mass. The top quark, in fact, is quite heavy.

    • by Snowhare (263311) on Monday May 31, 2010 @06:50PM (#32411998) Homepage

      It isn't their mass that makes them so unlikely to interact with ordinary matter. It is because they don't interact via the Electromagnetic or Strong Nuclear forces (at least not at the energies we are discussing here). Because we can't use gravity to directly detect them (or any other elementary particle) because of its incredible weakness, that leaves only the Weak Nuclear force, which is *extremely* short range. That short range means that a neutrino must pass *very* close to an electron or a quark to have any chance what-so-ever of interacting: Something like 10 to the minus 16th power meters. For comparison, a hydrogen atom has a diameter of around 10 to the minus 10th meters - or a million times larger.

      A single *proton* has a diameter of around 10 to the minus 15th meters - or still 10 times larger than the distance in question.

      So hundreds of neutrinos could pass directly through the very nucleus of an atom and *still* not interact with anything. And that is matter with a density more than a trillion times as dense as anything in your ordinary experience.

      To neutrinos, other matter barely exists at all.

    • by sjames (1099)

      You have mass. Now, tackle an elephant.

      In a similar way, neutrinos have so little mass compared to even hydrogen that they don't really interact.

    • by cowscows (103644)

      Supposedly if you took a hydrogen atom and scaled it up so that the single proton nucleus was the size of a basketball, the electron would end up as a tiny spec "orbiting" miles away. The proton is the center, and the electron forms the outer edge of the atom. But all of that space in between is empty. Even take a heavier atom, like lead and scale it up. You get more basketballs hanging out at the center, then a whole bunch of empty space, then a bunch of tiny electrons flying around. The heaviest, most d

  • We finally understood the universe, so it has been replaced with something even more perplexing.
  • Robust result? (Score:3, Insightful)

    by harryjohnston (1118069) <harry.maurice.johnston@gmail.com> on Monday May 31, 2010 @10:02PM (#32413454) Homepage

    Offhand, this doesn't seem like a very robust result - we're only talking about a single observation, after all. Does the equipment allow them to determine the source of the observed tau neutrino? How can they be sure that it came from the muon neutrino stream from CERN rather than being random background?

    There's also no mention of a control, e.g., another tau neutrino detector close to the same muon neutrino source. Even if there was, is a single detection versus no detections statistically significant?

  • by SigNick (670060) on Tuesday June 01, 2010 @05:22AM (#32416070)

    1. If an electron neutrino can spontaneously transform to a tau neutrino with higher mass, where exactly does the required energy come from? Alternatively, when a tau neutrino transforms to an electron neutrino, where does the extra energy disappear?

    2. If neutrinos have mass, then they are restricted to speeds below c. If they are accelerated to near c, then according to the relativistic energy-momentum equations they should have colossal mass, not miniscule (just like electrons, for example). Is there any evidence of observing neutrinos with huge energies?

    The Wiki article about neutrino oscillation paints the picture that the oscillation is a pseudo-illusionary quantum mechanical effect, and therefore questions like the two above are meaningless. Smells more like handwavium to me.

    Could a real physicist push back the veil of shadows one bit? Pretty please? =)

    • by volpe (58112)

      If they are accelerated to near c, then according to the relativistic energy-momentum equations they should have colossal mass, not miniscule

      (ob-IANAP)
      "Mass" means "proper mass" (or "rest mass"). The concept of "relativistic mass" (i.e. calling it such) has been out of vogue for more than 40 years.

      • the mass is a scalar, so it cannot change in Lorentz transformations. Scalars are not subject to change in Lorentz transformations. Therefore it's mot mass that increases, but momentum, you know p=m*v. Velocity is a vector, and in fact that vector is the value that makes momentum going to infinity. It seems as if mass was increasing, but in fact it is momentum increasing. But also it is not velocity strictly increasing to inf, because velocity isn't going to infinity either. I'd need to show you the derivat

    • by Young Master Ploppy (729877) on Tuesday June 01, 2010 @08:30AM (#32417022) Homepage Journal

      I'm not a "real" physicist - but I did study this at undergrad level, so here goes:

      Heisenberg's Uncertainty Principle ( http://en.wikipedia.org/wiki/Uncertainty_principle [wikipedia.org] ) states that there must always be a minimum uncertainty in certain pairs of related variables - e.g. position and momentum, i.e. the more accurately you know the position of something, the less accurately you know how it's moving. Another related pair is energy and time - the more accurately you know the energy of something, the less accurately you know when the measurement was taken.

      (disclaimer - this makes perfect sense when expressed mathematically, it onlysounds like handwavery when you translate it into English, as words are ambiguous and mean different things to different people)

      Anyway, this uncertainty means that there is a small but non-zero probability of a higher-energy event occuring in the history of a lower-energy particle (often mis-stated as "particles can borrow energy for a short time, but check the wiki page for a more accurate statement). It sounds nuts, I know, but it has many real-world implications that have no explanation in non-quantum physics. Particles can "tunnel" through barriers that they shouldn't be able to cross, for instance - this is how semi-conductors work.

      By implication, there is a small probability of the neutrino acting as if it had a higher energy, and *this* is how neutrino-flipping occurs without violating conservation of energy.

    • > 1. If an electron neutrino can spontaneously transform to a tau neutrino
      > with higher mass, where exactly does the required energy come from?
      > Alternatively, when a tau neutrino transforms to an electron neutrino, where
      > does the extra energy disappear?

      Think of it as oscillating between a higher rest-mass state moving slower and a lower rest-mass state moving faster (yes, I know that isn't "really" what happens). The momentum doesn't change.

      > 2. If neutrinos have mass, then they are restri

  • by ProteusQ (665382) <dontbother@n o w here.com> on Tuesday June 01, 2010 @01:22PM (#32420656) Journal

    This reminds me of the /. post a few days ago about those who are ignorant of science and proud to be so. This is how I think some of them might perceive this situation:

    Last week, a Normal would have been told by Those Who Do Science that a neutrino has no mass, and that is the end of the matter. A non-physicist has nothing to contribute to the discussion. Persistent disagreement amounts to sheer ignorance, so keep quiet.

    But now, it would appear that either neutrinos have mass or the Standard Model is wrong. Science has revealed its own ignorance. Everyone who was wrong last week is right this week. But the message to the Normals remains the same: it doesn't matter that we were wrong last week; eventually, We Who Do Science get it right. You still have nothing to say. Keep quiet.

    The Normals perceive the above and conclude that it's hypocrisy. Hence, they can ignore science and be proud that they are smart enough to avoid hypocritical know-it-all's.

    BTW: Yes, this is post if Offtopic, but it's not Flamebait or Troll. I'm not agreeing with this POV; I'm passing on my perception of it. And how else can one discuss the interrelationship between topics without being regarded as Offtopic in regards to one post or the another?

    I wish I had an answer of how to fix the above problem. Eliminating arrogant PhD's would be helpful, but that would leave all of the arrogant Normals -- and the rest of us aren't free from shocking amounts of arrogance at times, either. We could use another Sagan to highlight that math+science is a process that anyone can join in on once the ground-rules are mastered. However, it would me imperative that the next spokesperson not be hostile to religion -- the Normals are hypersensitive to this issue, and getting in their face about the matter only increases the alienation. [Not saying that Sagan was hostile to religion -- just saying then next spokesperson cannot be.]

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