Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: DoctorBeaver on 02/01/2009 21:34:25
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I've just watched a program about the LHC. The presenter, Brian Cox (1 of the lead scientists at the LHC) was talking about the Higgs boson. He said that heavy particles are unstable and decay quickly so, as Higgs bosons are heavy, they no longer exist in the universe having long ago decayed.
No Higgs bosons have so far been detected. But particles such as the muon have been produced. So, if particles get their mass by interacting with Higgs bosons, how do these artificially created particles get their mass if Higgs bosons no longer exist in the universe and are too heavy to have been produced in accelerators so far?
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Good question. Assuming that this Brian Cox is right, then it would imply a flaw in the Higgs Model.
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He might have meant that the HBs decay quickly in the current conditions where the energy density is relatively low when compared with conditions just after the BB. The whole point of the LHC is to achieve higher energy levels than have been possible with other accelerators, to the point where the HB may exist long enough to detect, even if only through secondary reactions. In any case, the creation of electron/positron pairs from gamma photons raises the same issue.
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LeeE - if they had been created, no matter how quickly they decayed, there would have been a trace of some kind. What Professor Cox said was that they are too massive to have been produced so far. He worked with the Tevatron (prior to moving to the LHC) which, I believe, has a maximum energy of around 1.5-2TEv. The implication of what he said was that the Higgs boson must be more massive than that.
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I thought the Tevatron was on the boundary of HB creation, but the LHC should be well inside it. Not sure about that though - I'm not a particle scientist and thats just the impression I got.
However, I'm a bit confused by the statement that HBs no longer exist. If it is the HBs that confer mass, and things now have mass, how can a particle that no longer exists anywhere in the universe continue to do it's stuff? Hence the mention of electron/positron pair creation, which is occurring all the time somewhere in the universe. How can these newly created particles have mass if there are no HBs to confer it?
I think I must have missed something somewhere [???]
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LeeE - that's 1 of the things tht confused me about what he said. I just picked on particles created in colliders. He wouldn't confuse me half as much if he'd stuck to music.
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He wouldn't confuse me half as much if he'd stuck to music.
Yes, if he'd stuck to music we wouldn't feel so compelled to listen to him.
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He wouldn't confuse me half as much if he'd stuck to music.
Yes, if he'd stuck to music we wouldn't feel so compelled to listen to him.
Well, he (or, rather, his band) did have a Top 10 hit record a few years back. "Things Can Only Get Better", D-Ream
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Yes, I remember, and that's why I said what I did. <tongue-in-cheek-mode>I guess some people must have liked it though.</tongue-in-cheek-mode>
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I never liked it. But it was Tony Blair's favourite record, wasn't it? I know it was the Labour Party anthem.
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Exactly. While I'll admit that it was a catchy little number, it's association with New Labour(tm) has left it in the same category as Nazi SS uniforms, which arguably were very smart.
Heh - I was trying to be funny but only seem to be sounding even more serious.
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However, I'm a bit confused by the statement that HBs no longer exist. If it is the HBs that confer mass, and things now have mass, how can a particle that no longer exists anywhere in the universe continue to do it's stuff? Hence the mention of electron/positron pair creation, which is occurring all the time somewhere in the universe. How can these newly created particles have mass if there are no HBs to confer it?
I'm going to speculate here, but if the Higgs field behaves like other fields, the interactions that give particles mass might just be due to the exchange of virtual Higgs particles. (Just like electromagnetic interactions often involve virtual photons). By their virtue of being virtual, these Higgs particles would be undetectable. The Higgs particle they want to measure would have to be a real particle, which takes a lot of energy to make.
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jpetrucelli - you could well be right. That seems to sound familiar.
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Yes, that sounds reasonable.
Even though the idea of virtual particles clearly works, I've got to admit that there's something about them that bothers me (this probably being the fact that they don't actually exist, but only virtually exist). I'm not going to nay-say them just on that basis though.
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Lee - I know what you mean. I have trouble accepting them. They just seem wrong. I know that's no scientific basis for an opinion and so much of QM is counter-intuitive.
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However, I'm a bit confused by the statement that HBs no longer exist. If it is the HBs that confer mass, and things now have mass, how can a particle that no longer exists anywhere in the universe continue to do it's stuff? Hence the mention of electron/positron pair creation, which is occurring all the time somewhere in the universe. How can these newly created particles have mass if there are no HBs to confer it?
I'm going to speculate here, but if the Higgs field behaves like other fields, the interactions that give particles mass might just be due to the exchange of virtual Higgs particles. (Just like electromagnetic interactions often involve virtual photons). By their virtue of being virtual, these Higgs particles would be undetectable. The Higgs particle they want to measure would have to be a real particle, which takes a lot of energy to make.
That sounds very reasonable.
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You seem here to have concluded that the correct answer is the explanation. You have to remember that quantum mechanical interactions are always a blend of the effects of ALL THE POSSIBLE ACTIONS that could have taken place in any given interaction scenario this will include interactions with virtual Higgs particles. That is assuming that the Higgs model is correct and the Higgs boson can be found. If it can't then it's back to the drawing board folks!
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QM is considered, quite rightfully, to be very successful; without it, we wouldn't have the computers with which to post on this forum. However, QM only manages to describe what occurs in a causal way; it doesn't really explain why those things happen except in terms of abstract laws. In this sense, QM is more like a behavioural study of something rather than a theory; it doesn't attempt to describe what the particles are, only what they will do. It won't ever say what a quark or an electron actually is.
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So, in summary, artificially created particles acquire their mass by interactng with virtual Higgs bosons. Is that right?
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I have trouble with the idea that QM somehow allowed transistors and computers to be invented. I was around most of that time. It seemed to me that it was us lowly engineers that brought it about. [:)] And I never could understand how the Higgs Boson could give mass to a particle.
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Particles gain mass/energy when they move through electromagnetic fields it's back to the old question does the univese have an ether.
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I have trouble with the idea that QM somehow allowed transistors and computers to be invented.
I've wondered that myself. I remember a physicist once telling me that without QM I wouldn't have a microwave oven. [???]
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Semi conductor amplifiers were discovered by amateurs poking about with "cat whiskers" and adding batteries on the Galena Crystal's of their wirelesses in the twenties it was no Manhattan like scientific project.