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Neutrinos, Muons and the Standard Model
scorp1us writes: "I can't believe I haven't seen this posted yet. Apparently experiments in particle physics aren't holding to theory. The result: a search for a new form of energy or matter. Read about it in the Post. No wonder witches weigh as much as a duck."
I think that this is maybe not so surprising. Theories in particle physics are very unlike a lot of other theories. There's not much evidence sitting around for some of these things, and as new evidence comes in, the theories change.
This is true for any scientific endeavor, but the changes are much more rapid in things like high-energy physics.
In short, I'm just saying that it shouldn't be taken as a "radical breakthrough" just because someone had the muon equation wrong, because it was going to happen at some point.
Come on, give it up, that's
This was posted a few days ago, along with links to much better articles:
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http://slashdot.org/article.pl?sid=01/11/08/22212
What the experiment shows is that the plan-vanilla Standard Model doesn't perfectly match reality. This is a surprise to nobody.
The results give a tantalizing look at one region of this breakdown, but proclaiming "a new form of energy or matter" is a bit premature at this point. What this will actually do is help confirm, refute, or fine-tune a few of the new models that are replacement candidates for the Standard Model.
Since neutrinos are so small, most of the time they passed through the nucleus without affecting it. The frequency of collisions told scientists about the electromagnetic forces that affect how neutrinos behave -- the so-called weak forces. The scientists found slightly fewer interactions with one of the weak forces than had been predicted by the Standard Model, physicists' current description of fundamental forces and particles. Since the model is very precise, scientists concluded that the difference was significant. (emphasis mine)
This is what I love about science. Here we have the Standard Model, formed from exhaustively detailed tests over the last 30 years. As the article states, the model is very precise, and slight deviations are significant issues. However, rather than scrap the entire idea, or announce that the tests were probably flawed, or decry the scientists who performed the tests as heathens and radicals, here we see that the community will embrace this new data and reform the model in such a way as to make it work.
This is the beauty of science. If something doesn't work out the way it was supposed to, if a theory doesn't fit with the cold, hard data, the majourity of scientists will go out of their way to fix the theory (not the data). Scientists are always going out of their way to keep each other in check; at any given time one scientist may be checking some prominent theory or another. It keeps them honest, and while the system isn't fool proof, it's damn tight.
Sometimes it's great to be a geek.
~Aaron.
student of animation and the fine arts
Apart from that, it is an interesting result, but only three sigma from the standard model, which is not really too much if you want to announce something groundbreaking. Sometimes even four sigma results turn out to be just experimental outliers.
Absolutes and hyperbole are the refuge of the close minded. They are simply not ruling out any possibilities without further confirmation.. this is an excellent practice I feel. They suspect they could be onto something big, but don't want to "over hype" it.
"The wise man is the one who realizes that he knows nothing." - Socrates
"Mind, as manifested by the capacity to make choices, is to some extent present in every electron." -Freeman Dyson
That's the mark of a good scientist.
Really.
When you have beliefs about the world and universe that are absolute, the term for that is "religion". Good scientists know that they don't know.
i don't believe you. ideas have momentum, but historically, science has gotten more and more accurate at describing the natural world.
many times existing theory has inertia, but if the evidence is strong enough, the more correct hypothesis will subplant the weaker one.
now, if you are going to accuse people who resist new ideas of small mindedness, then you are doing them a great disservice. Skepticism must be on both sides of a scientific dispute. Fawning over and prematurely accepting new theory is just as bad for Good Science as being to stubborn to accept that your idea is wrong.
if you want to dispute this, show me some evidence. Recall that astronomy has gone from a geo-centric world (with heaven in the out spheres)to a helio-centric universe. Newtonian mechanics were replaced by general relativity. the whole history of science shows the same trends.
A: None. The Universe spins the bulb, and the Zen master merely stays out of the way.
I think the principle of falsifiability has gone out of vogue almost entirely. Karl Popper, who popularized the principle of falsifiability, shifted to a weaker form of the principle in his own lifetime, and post-modern critiques of the principle have eroded its popularity greatly.
The main critique against the principle is that scientific propositions require auxilliary hypotheses to have any predictive value. When a specific prediction is falsified, it is possible to "get around" the problem by modifying the auxilliary hypotheses. Since such modification to auxilliary hypotheses is considered a normal part of the scientific process, falsifiability doesn't really work very well.
Or something like that... it's been a couple of years since I studied this stuff.
Disclaimer: I used to study gravity, not particle physics. That said...
Neutrinos only interact with other particles through the electroweak force (ignoring gravity for the moment). There are three bosons which "carry" the electroweak force, called W+, W-, and Z0. The discrepency with the Standard Model seems to occur with the Z0 (called the neutral current in the paper).
There are several things it could be other than a new force. The scientists will have to eliminate all forms of background noise and detector errors, the possibility that it was just some sort of hadron resonance, and a lot of other things.
It is amazing how sensitive particle experiments can be. I remember reading about one that had to filter out (among other things) the noise caused by the motion of the moon orbiting the earth in order to extract the signal.
That said, I think they may be on to something.
going to sacrifice a couple karma points by going wildly off topic, but this is something that's been bugging me lately - the continual bitching when the occasional article gets rerun. (please note, i am not accusing the parent poster of this. that was just a helpful link for those that weren't reading the science section).
newspapers rerun stories all the time. the news networks are 90% recycled, content free info. as a general rule, /. does a pretty fine job of delivering up spanking fresh content, filtered for interest, packaged and delivered free (free, goddamnit!) to my desktop.
it wasn't that many years ago when i had to make do with the anemic science and technology section of the daily rag.
damn. i feel better. thanks /.
This is the voice of World Control. I bring you Peace.
I wouldn't make any long term plans based on this paper. The "one chance in 400" is misleading -- if you look at the paper, what it's really saying is that their experimental result differed from their theoretical result by three standard deviations (three sigma). On the face of it, this isn't very impressive. The trouble with straightforward statistical analysis in this fasion is that particle physics is hard. Experiments are being done at the limits of detectability, and often in ways that have never been done before. Because of this, it's extremely hard to tell what one sigma is, since it's entirely possible (and somewhat likely) that you just don't understand the pitfalls yet. Particle physicists have a rule of thumb for cases like this: a six sigma effect pans out about half the time. This is only a three sigma result, so adjust your expectations accordingly. A result like this is worth publishing, but won't persuade many people unless followup experiments get the same results (with *much* better statistics).
Please don't be so hasty!
Consider what this result (if it bears up) will mean. There is of course a difference between electromagnetic and weak forces below electroweak unification energy (about 1 TeV) due to the spontaneous symmetry breaking at the EWPT (electroweak phase transition)... it is this which makes the "B" singlet and W0 mix into the photon and Z0. According to the standard model, the charge of the neutrino is 0 and the photon does not couple with it, so the poster you reply to was actually correct about that.
The electroweak mixing parameter is called the Weinberg angle, theta_W. This experiment was intended as a new, precise, independent measurement of theta_W. It seems that this new measurement is inconsistent with the previous world average. This leads us to believe there is something wrong with the measurement (quite possible), or something wrong with our understanding of electroweak unification (also quite possible).
If the latter is true, your entire post is founded on a theory which, although it seems to be mostly correct, may need a certain amount of fixing up. Just because some people got a Nobel Prize, it does not follow that their theory will stand the ultimate test.
I am looking forward to seeing how this will turn out. Even if there is "something" here, I personally suspect that the standard model will need only minor adjustments.
But then, that's what people though when Michelson and Morley got their famous null result (and the first time they published, they had only a 2.5 sigma result... of course, physicists (and everyone else) know even less about statistics back then.)