Actually there are models that do that, and it would be called a "composite Higgs". If there's a composite Higgs I pay out less in my bet than if it's a single Higgs. It's still a Higgs though.
... the difference between a mathematical model of how some scenario behaves, and a religion, is enormous. Can I check - is that actually your point? Because physics is, ultimately, a collection of algorithms that tell us how we expect a given situation to evolve. Nothing more, and nothing less. The interpretation of gravity as the "bending" of the "fabric" of spacetime comes from an extremely successful (and, when applied outside of its range of validity, inaccurate) set of algorithms. [Total aside: it's extremely persuasive, given that it follows almost directly from pointing out that acceleration cancels gravity and that gravity imparts the same acceleration on objects of wildly different masses, which is the hallmark of fictional forces such as coriolis or centrifugal forces -- they *definitely* exist, and don't let some high-school graduate tell you different, but they only exist when you view them from a weird reference frame. Change the reference frame and the force vanishes. This is a way of approaching the "weak equivalence principle", and is a major underlying philosophy of general relativity. But while it may be extremely persuasive, it's also inaccurate when you apply it outside of its realm of validity, such as in volumes of the order of 10^-40m across.]
So GR gives a good example of physics as a collection of algorithms - and then it's your choice whether you believe the interpretation or not. Personally I find it very convenient to believe the interpretation, at least when I'm working within the theory since it doesn't exactly impact on my everyday life otherwise. But that's a choice and I know of eminent physicists (and Weinberg is a good example, or at least used to be; I don't know if he's changed his viewpoint in the last 35 years though) who don't really entertain the curvature interpretation as anything more than a mathematical convenience.
In that sense, maybe you could judge it as "religion" - but I'd still suggest that that's pushing the definition of "religion" somewhat.
It means there are now tight limits on where it could possibly be. No-one is claiming it's been found (well, other than the tabloid press you mention who've been doing the damndest to do exactly that), but that now there are only narrow ranges where it could lie. The nice thing is that they *are* ranges. I'm old enough to remember when all we could say about the mass of the Higg's boson was that it was above something like 100GeV, and now we know that if it does exist, it's in increasingly narrow sections of parameter space.
What I'd like is that it isn't there. Partly because I've never been entirely comfortable with the Higg's (or in some respects the direction of particle theory since about 1970 or so), but mainly because if it is there I'm liable to lose a bet I'd much rather have won.
Thanks for the reply:) In that case, yes, I agree - there are still some crackpot papers that can come up (and there used to be a lot more before they changed the endorsement system; I remember my favourite was about ball-lightning being produced by primordial black holes), but journalists picking up some paper on the arXiv and running much further with it than the authors would have themselves, that's very irritating...
I disagree, it most definitely is something more. Most papers on the arXiv are "preprint"s - that's what the server is for, after all. It means they're posted before the journal publishes them. If you check most papers on the arXiv about five or six months after submission they're updated with a journal reference. It's a repository for papers. Some are unpublished, yes, and some are unpublished because they failed peer-review (although some are unpublished because for whatever reasons the author didn't submit them), but the vast majority are the same papers that you'd read in Physical Review or the Astrophysical Journal.
Why are you "biased against" arXiv preprints? There is very little crackpot science allowed through to the arXiv these days - so it's what it was intended to be, a place for physicists to post their results before publication. What many do is post their papers after acceptance by a journal; others post them when they first submit. Both approaches are fine. Papers can (and generally are) revised along lines suggested by the journals' referees, or if the author simply sees a way of making something clearer, or corrects some mistake. Working in the field, I can assure you that almost all of us keep up with the literature almost purely via the arXiv.
Yeah but they explode as a result of being unable to fuse iron into anything heavier. Iron is extremely hard to fuse. When the star converts everything into iron and stops burning there's no radiation pressure to support it anymore, and when you consider just how sodding massive a star is, that's pretty serious. It starts to implode, and the temperature rises. In previous times when it exhausted a fuel (when it stopped burning hydrogen, for example) the increase in temperature reached a level at which the star could fuse a heavier element such as helium. This cycle stops when it's onto iron, and the collapse continues, and continues, and the enormous envelope (still mainly hydrogen and some helium) falls faster and faster until it slams into the iron core, and bounces. This bounce is enormously energetic and provides enough energy to restart the entire sequence, and the envelope rapidly fuses its way through hydrogen all the way up to iron - and beyond. (Incidentally, the only natural way to produce even a trace of heavier elements that I'm aware of is in a supernova.)
Because if there was a meltdown you'd trigger a supervolcano or a megaquake on the San Andreas fault, or annihilate Tokyo or some such rubbish, I'm sure.
(Also, you'd irradiate the soil and the groundwater something rotten.)
Fair enough, I'll have to read the new paper - I've not done that yet.
Out of interest, I get the impression you're not a fan of ditching special relativity - have you any other suggestions as to what's happening, be they unaccounted systematics or new physics?
Everything to do with supernovae is model dependant:) But when a "prediction" makes a lot of sense and matches a result reasonably well, it makes sense to assume it at least has some validity. In this case, reactions in the core of an imploding neutron star *will* emit neutrinos, and those neutrinos are not going to interact with the surrounding neutron star to any appreciable degree compared to the photons - instead, it makes sense that the neutrinos will break free before the photons.
Details, of course, are a totally different matter and one on which I'm at least as ignorant as anyone else.
(btw to account for the known results at the minute it would seem more feasible, from a really naive point of view, that neutrinos have both a real and an imaginary mass. i have no idea what that would do to modern particle physics, or to relativity, or to cosmology, but i'm willing to bet that it wouldn't be pretty.)
An imaginary mass would more likely account for it.
What I *don't* know, and genuinely have no idea, is whether a non-positive mass would account for the neutrino oscillations we observe (which guarantee neutrino mass when interpreted through more-or-less standard particle physics). I don't think a negative mass could possibly account for the cosmological hints that neutrinos have mass - the cosmological bounds are actually tighter than the experimental bounds by quite some way, although there are always questions of applicability - but I have no idea if anyone's considered an imaginary mass. My gut instinct says that it wouldn't work at all within the bounds of current theory, and neither would a negative mass, but it would have to be considered. In any event it would involve a very thorough restructuring of cosmology, in a theory where neutrinos somehow have either negative or, potentially a lot more damagingly, imaginary mass.
Further, it would be very interesting to probe any cosmological consequences of causality-violating neutrinos. Neutrinos interact, albeit very weakly, with other particles, and any violations of causality could have interesting effects on cosmology. More directly, though, neutrinos have *energy*, regardless of whether or not they possess mass, and they have pressure, and those generate gravitational effects. Neutrinos that could violate causality could have extremely significant effects on structure formation in the universe.
(by the way, i just re-read my original post and i did just mention "kinks and ripples". you could find a model where those are on scales much larger than the planck scale and most models generically would - cosmological models of branes rely on that - but you're totally right that out of context those ripples would be expected to be basically planck scale. my loose language, sorry)
Quite possibly, but depending on the structure of the brane I could argue it would happen anyway. The model you could most easily base this on is actually 5D rather than 11D -- a hell of a lot easier -- and while you can have a 3+1D brane that's flat (ie obeys special relativity) it's embedded *curved* into the 4+1D bulk. (This is called "extrinsic curvature", as opposed to the "intrinsic curvature" which in this rough model is vanishing.) Then a neutrino could take a shortcut no matter whether there are Planck-scale oscillations or not - because the brane is embedded, on large scales, with a significant extrinsic curvature.
We've no real direct evidence that it propagates at light speed though - also the background behaviour is simply that gravity leaks off the brane and into the bulk, which reduces it from a force of the same rough strength as the others to a force that is enormously weaker than the others. It's the waves through it that look like they could propagate off the brane and scatter back on... or not. I'm five or six years out of date on this, I must admit, so don't trust me that gravitational waves in braneworld theories really are liable to break causality - but there was a genuine, reasoned concern that they did.
So far as I understand it, and this isn't my field, it's one of the possible explanations for the neutrino results. (Much more likely to my mind are unaccounted systematics - most likely due to clock rates *predicted* by relativity... but obviously I don't know that; I'm not a member of OPERA nor even a particle physicist, just a cosmologist.)
Well, that's why it has to be very, very carefully tested. But ultimately if it contradicts special relativity then it contradicts special relativity - we'll get more data on different experiments and see what theories we can build to account for them.
But yes, I very strongly suspect that there's a systematic error they've not accounted for.
A supernova explodes from the inside - so the initial burst of photons and neutrinos from the supernova is shielded behind the rest of the neutron star. Light gets blocked, but neutrinos don't, so they get out first.
It's quite ingrained to think of neutrinos as being massless, which would give them a single velocity, that of light. That might not be helping.
Since at least two of the neutrino species apparently *aren't* massless, they then would certainly have a different, and slightly slower, velocity. But they're so light that that velocity would be somewhere up near the velocity of light - so while they won't have the same velocity, I imagine the spread will be fairly unimportant.
Yes, maybe. My (more or less) professional opinion is that the experiment almost certainly hasn't shown this, and instead it will either turn out to be experimental error or a *demonstration* of relativity (either special or general; both affect clock rates in ways that can be significant for this experiment), but yes, it could finally be some experimental evidence against relativity. And since you're quite right in saying that general relativity is definitely "wrong" in that it's not a fundamental theory and cannot be treated as such, this shouldn't be terrifying - just very exciting.
But I'll withhold judgment for a while - I'm very sceptical about these results.
1) Yes, it could, they've attempted to take that into account. The main error would be in the length of the neutrino pulse; a long pulse is easier to detect (I think ~2000 neutrinos, or perhaps even more) but it's hard to pin down a precise time. The repeat experiment used very short pulses, which are harder to detect (~20 neutrinos) but which yield much more precise timings.
2) All observations so far are suggesting that neutrinos have a positive mass (or, to be more picky, that at least two of the neutrino species have a positive mass) of the order of a tenth of an electron volt or less. (Also, I think it would involve an imaginary mass to move faster than light, at least if you want to stick within current relativity - this result would suggest we might not want to do that, though.)
3) Yes. For instance, if we're confined to a 3-brane -- basically, a three-dimensional sheet that we and everything around us is trapped on -- and neutrinos are allowed to leak slightly from the brane then little kinks and ripples in the brane will let them take short-cuts through the other seven spatial dimensions. Gravity can do the same, but the idea is that neutrinos would be more tightly trapped to the brane, while gravitons can roam freely.
Absolutely. They're planning on rerunning the experiment again and loosening their dependence on GPS to test this. Another possible (and loosely related) contaminant that doesn't involve new physics is the different clock rate at the two labs coming from the different gravitational field strength. Personally I'd expect that to be pretty insignificant, but it has to be checked before we all go haywire shouting that neutrinos are propagating off the brane, or whatever.
Not in a supernova burst. The initial implosion is deep inside the neutron star, and there's a lot of matter shielding it. Light interacts with matter, so it gets delayed on its way out, but the neutrino burst from that initial implosion doesn't. The predicted delay was of the same order of magnitude as the delay seen in SN1987a.
Slashdot Mirror
Someone mod this guy up, especially for point (2).
Actually there are models that do that, and it would be called a "composite Higgs". If there's a composite Higgs I pay out less in my bet than if it's a single Higgs. It's still a Higgs though.
... the difference between a mathematical model of how some scenario behaves, and a religion, is enormous. Can I check - is that actually your point? Because physics is, ultimately, a collection of algorithms that tell us how we expect a given situation to evolve. Nothing more, and nothing less. The interpretation of gravity as the "bending" of the "fabric" of spacetime comes from an extremely successful (and, when applied outside of its range of validity, inaccurate) set of algorithms. [Total aside: it's extremely persuasive, given that it follows almost directly from pointing out that acceleration cancels gravity and that gravity imparts the same acceleration on objects of wildly different masses, which is the hallmark of fictional forces such as coriolis or centrifugal forces -- they *definitely* exist, and don't let some high-school graduate tell you different, but they only exist when you view them from a weird reference frame. Change the reference frame and the force vanishes. This is a way of approaching the "weak equivalence principle", and is a major underlying philosophy of general relativity. But while it may be extremely persuasive, it's also inaccurate when you apply it outside of its realm of validity, such as in volumes of the order of 10^-40m across.]
So GR gives a good example of physics as a collection of algorithms - and then it's your choice whether you believe the interpretation or not. Personally I find it very convenient to believe the interpretation, at least when I'm working within the theory since it doesn't exactly impact on my everyday life otherwise. But that's a choice and I know of eminent physicists (and Weinberg is a good example, or at least used to be; I don't know if he's changed his viewpoint in the last 35 years though) who don't really entertain the curvature interpretation as anything more than a mathematical convenience.
In that sense, maybe you could judge it as "religion" - but I'd still suggest that that's pushing the definition of "religion" somewhat.
It means there are now tight limits on where it could possibly be. No-one is claiming it's been found (well, other than the tabloid press you mention who've been doing the damndest to do exactly that), but that now there are only narrow ranges where it could lie. The nice thing is that they *are* ranges. I'm old enough to remember when all we could say about the mass of the Higg's boson was that it was above something like 100GeV, and now we know that if it does exist, it's in increasingly narrow sections of parameter space.
What I'd like is that it isn't there. Partly because I've never been entirely comfortable with the Higg's (or in some respects the direction of particle theory since about 1970 or so), but mainly because if it is there I'm liable to lose a bet I'd much rather have won.
Thanks for the reply :) In that case, yes, I agree - there are still some crackpot papers that can come up (and there used to be a lot more before they changed the endorsement system; I remember my favourite was about ball-lightning being produced by primordial black holes), but journalists picking up some paper on the arXiv and running much further with it than the authors would have themselves, that's very irritating...
"Nothing more, nothing less."
I disagree, it most definitely is something more. Most papers on the arXiv are "preprint"s - that's what the server is for, after all. It means they're posted before the journal publishes them. If you check most papers on the arXiv about five or six months after submission they're updated with a journal reference. It's a repository for papers. Some are unpublished, yes, and some are unpublished because they failed peer-review (although some are unpublished because for whatever reasons the author didn't submit them), but the vast majority are the same papers that you'd read in Physical Review or the Astrophysical Journal.
Why are you "biased against" arXiv preprints? There is very little crackpot science allowed through to the arXiv these days - so it's what it was intended to be, a place for physicists to post their results before publication. What many do is post their papers after acceptance by a journal; others post them when they first submit. Both approaches are fine. Papers can (and generally are) revised along lines suggested by the journals' referees, or if the author simply sees a way of making something clearer, or corrects some mistake. Working in the field, I can assure you that almost all of us keep up with the literature almost purely via the arXiv.
Yeah but they explode as a result of being unable to fuse iron into anything heavier. Iron is extremely hard to fuse. When the star converts everything into iron and stops burning there's no radiation pressure to support it anymore, and when you consider just how sodding massive a star is, that's pretty serious. It starts to implode, and the temperature rises. In previous times when it exhausted a fuel (when it stopped burning hydrogen, for example) the increase in temperature reached a level at which the star could fuse a heavier element such as helium. This cycle stops when it's onto iron, and the collapse continues, and continues, and the enormous envelope (still mainly hydrogen and some helium) falls faster and faster until it slams into the iron core, and bounces. This bounce is enormously energetic and provides enough energy to restart the entire sequence, and the envelope rapidly fuses its way through hydrogen all the way up to iron - and beyond. (Incidentally, the only natural way to produce even a trace of heavier elements that I'm aware of is in a supernova.)
Don't worry; if they're running beyond safety limits they'll disappear sooner or later.
Because if there was a meltdown you'd trigger a supervolcano or a megaquake on the San Andreas fault, or annihilate Tokyo or some such rubbish, I'm sure.
(Also, you'd irradiate the soil and the groundwater something rotten.)
Fair enough, I'll have to read the new paper - I've not done that yet.
Out of interest, I get the impression you're not a fan of ditching special relativity - have you any other suggestions as to what's happening, be they unaccounted systematics or new physics?
Everything to do with supernovae is model dependant :) But when a "prediction" makes a lot of sense and matches a result reasonably well, it makes sense to assume it at least has some validity. In this case, reactions in the core of an imploding neutron star *will* emit neutrinos, and those neutrinos are not going to interact with the surrounding neutron star to any appreciable degree compared to the photons - instead, it makes sense that the neutrinos will break free before the photons.
Details, of course, are a totally different matter and one on which I'm at least as ignorant as anyone else.
(btw to account for the known results at the minute it would seem more feasible, from a really naive point of view, that neutrinos have both a real and an imaginary mass. i have no idea what that would do to modern particle physics, or to relativity, or to cosmology, but i'm willing to bet that it wouldn't be pretty.)
An imaginary mass would more likely account for it.
What I *don't* know, and genuinely have no idea, is whether a non-positive mass would account for the neutrino oscillations we observe (which guarantee neutrino mass when interpreted through more-or-less standard particle physics). I don't think a negative mass could possibly account for the cosmological hints that neutrinos have mass - the cosmological bounds are actually tighter than the experimental bounds by quite some way, although there are always questions of applicability - but I have no idea if anyone's considered an imaginary mass. My gut instinct says that it wouldn't work at all within the bounds of current theory, and neither would a negative mass, but it would have to be considered. In any event it would involve a very thorough restructuring of cosmology, in a theory where neutrinos somehow have either negative or, potentially a lot more damagingly, imaginary mass.
Further, it would be very interesting to probe any cosmological consequences of causality-violating neutrinos. Neutrinos interact, albeit very weakly, with other particles, and any violations of causality could have interesting effects on cosmology. More directly, though, neutrinos have *energy*, regardless of whether or not they possess mass, and they have pressure, and those generate gravitational effects. Neutrinos that could violate causality could have extremely significant effects on structure formation in the universe.
(by the way, i just re-read my original post and i did just mention "kinks and ripples". you could find a model where those are on scales much larger than the planck scale and most models generically would - cosmological models of branes rely on that - but you're totally right that out of context those ripples would be expected to be basically planck scale. my loose language, sorry)
Quite possibly, but depending on the structure of the brane I could argue it would happen anyway. The model you could most easily base this on is actually 5D rather than 11D -- a hell of a lot easier -- and while you can have a 3+1D brane that's flat (ie obeys special relativity) it's embedded *curved* into the 4+1D bulk. (This is called "extrinsic curvature", as opposed to the "intrinsic curvature" which in this rough model is vanishing.) Then a neutrino could take a shortcut no matter whether there are Planck-scale oscillations or not - because the brane is embedded, on large scales, with a significant extrinsic curvature.
We've no real direct evidence that it propagates at light speed though - also the background behaviour is simply that gravity leaks off the brane and into the bulk, which reduces it from a force of the same rough strength as the others to a force that is enormously weaker than the others. It's the waves through it that look like they could propagate off the brane and scatter back on... or not. I'm five or six years out of date on this, I must admit, so don't trust me that gravitational waves in braneworld theories really are liable to break causality - but there was a genuine, reasoned concern that they did.
So far as I understand it, and this isn't my field, it's one of the possible explanations for the neutrino results. (Much more likely to my mind are unaccounted systematics - most likely due to clock rates *predicted* by relativity... but obviously I don't know that; I'm not a member of OPERA nor even a particle physicist, just a cosmologist.)
Well, that's why it has to be very, very carefully tested. But ultimately if it contradicts special relativity then it contradicts special relativity - we'll get more data on different experiments and see what theories we can build to account for them.
But yes, I very strongly suspect that there's a systematic error they've not accounted for.
Carlo Contaldi disagrees with you. I'm not going to argue relativity with Contaldi, he's very good.
A supernova explodes from the inside - so the initial burst of photons and neutrinos from the supernova is shielded behind the rest of the neutron star. Light gets blocked, but neutrinos don't, so they get out first.
It's quite ingrained to think of neutrinos as being massless, which would give them a single velocity, that of light. That might not be helping.
Since at least two of the neutrino species apparently *aren't* massless, they then would certainly have a different, and slightly slower, velocity. But they're so light that that velocity would be somewhere up near the velocity of light - so while they won't have the same velocity, I imagine the spread will be fairly unimportant.
Yes, maybe. My (more or less) professional opinion is that the experiment almost certainly hasn't shown this, and instead it will either turn out to be experimental error or a *demonstration* of relativity (either special or general; both affect clock rates in ways that can be significant for this experiment), but yes, it could finally be some experimental evidence against relativity. And since you're quite right in saying that general relativity is definitely "wrong" in that it's not a fundamental theory and cannot be treated as such, this shouldn't be terrifying - just very exciting.
But I'll withhold judgment for a while - I'm very sceptical about these results.
1) Yes, it could, they've attempted to take that into account. The main error would be in the length of the neutrino pulse; a long pulse is easier to detect (I think ~2000 neutrinos, or perhaps even more) but it's hard to pin down a precise time. The repeat experiment used very short pulses, which are harder to detect (~20 neutrinos) but which yield much more precise timings.
2) All observations so far are suggesting that neutrinos have a positive mass (or, to be more picky, that at least two of the neutrino species have a positive mass) of the order of a tenth of an electron volt or less. (Also, I think it would involve an imaginary mass to move faster than light, at least if you want to stick within current relativity - this result would suggest we might not want to do that, though.)
3) Yes. For instance, if we're confined to a 3-brane -- basically, a three-dimensional sheet that we and everything around us is trapped on -- and neutrinos are allowed to leak slightly from the brane then little kinks and ripples in the brane will let them take short-cuts through the other seven spatial dimensions. Gravity can do the same, but the idea is that neutrinos would be more tightly trapped to the brane, while gravitons can roam freely.
Absolutely. They're planning on rerunning the experiment again and loosening their dependence on GPS to test this. Another possible (and loosely related) contaminant that doesn't involve new physics is the different clock rate at the two labs coming from the different gravitational field strength. Personally I'd expect that to be pretty insignificant, but it has to be checked before we all go haywire shouting that neutrinos are propagating off the brane, or whatever.
Not in a supernova burst. The initial implosion is deep inside the neutron star, and there's a lot of matter shielding it. Light interacts with matter, so it gets delayed on its way out, but the neutrino burst from that initial implosion doesn't. The predicted delay was of the same order of magnitude as the delay seen in SN1987a.