Thirty years of the Standard Model
Sep. 28th, 2004 09:30 pm![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
mmcirvinThis fall is the thirtieth anniversary of the "November Revolution", the shift in particle physics that happened as a result of the discovery of the J/Ψ particle, which fulfilled the clearest testable prediction of the emerging quark model and electroweak theory.
Ever since then, particle physics has been to some extent the victim of its own success. There has been a pretty stable picture, called the Standard Model, of what the most fundamental well-established laws of physics are, and new experimental discoveries have been embellishments around the edges: the third generation of fundamental particles, the not-very-surprising discovery of neutrino mass, the narrowing of ranges in which the Higgs particle or something like it might be found. It's easy to tweak the Standard Model to incorporate this stuff without it seeming terribly forced. There are ideas out beyond the edge of current observation—grand unified theories, supersymmetry, strings, quantum gravity—but the connection to things we can measure hasn't arisen, except in a gradual winnowing of the simplest and most outrageous ideas through negative results.
Which is why the phenomena of dark matter and especially dark energy are so exciting. This is clearly fundamental physics way, way beyond the Standard Model, and not off in some unobservable realm but accessible, at least in its gravitational effects, to telescopes. We might be escaping beyond the Standard Model at last.
Ever since then, particle physics has been to some extent the victim of its own success. There has been a pretty stable picture, called the Standard Model, of what the most fundamental well-established laws of physics are, and new experimental discoveries have been embellishments around the edges: the third generation of fundamental particles, the not-very-surprising discovery of neutrino mass, the narrowing of ranges in which the Higgs particle or something like it might be found. It's easy to tweak the Standard Model to incorporate this stuff without it seeming terribly forced. There are ideas out beyond the edge of current observation—grand unified theories, supersymmetry, strings, quantum gravity—but the connection to things we can measure hasn't arisen, except in a gradual winnowing of the simplest and most outrageous ideas through negative results.
Which is why the phenomena of dark matter and especially dark energy are so exciting. This is clearly fundamental physics way, way beyond the Standard Model, and not off in some unobservable realm but accessible, at least in its gravitational effects, to telescopes. We might be escaping beyond the Standard Model at last.
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Date: 2004-09-29 03:24 am (UTC)Not everyone would agree with you on that. I had a bit of a discussion with a theorist -- sorry, now I can't remember who it was -- who maintains massive neutrinos are outside the Standard Model. I think what he said when pressed on the question was, yes, you can put neutrino masses into the theory just like the other particle masses, and that will work; but then you're left with trying to explain the huge difference between neutrino masses and all the other masses. You can put that huge mass difference in by fiat, but it cries out for an explanation not provided by the Standard Model.
I wasn't particularly convinced by this line of reasoning -- it wouldn't be the first fine tuning problem found in the Standard Model -- but apparently some theorists are. Of course to some extent it's an argument over terminology; what, really, is the Standard Model?