" In the same movie, Emperor Joseph II offers Mozart some musical advice: "Your work is ingenious. It's quality work. And there are simply too many notes, that's all. Just cut a few and it will be perfect." The emperor was put off by the surface complexity of Mozart's music. He didn't see that each note served a purpose-to make a promise or fulfill one, to complete a pattern or vary one.
Similarly, at first encounter people are sometimes put off by the superficial complexity of fundamental physics. Too many gluons!
But each of the eight color gluons is there for a purpose. Together, they fulfill complete symmetry among the color charges. Take one gluon away, or change its properties, and the structure would fall. Specifically, if you make such a change, then the theory formerly known as QCD begins to predict gibberish; some particles are produced with negative probabilities, and others with probability greater than 1. Such a perfectly rigid theory, one that doesn't allow consistent modification, is extremely vulnerable. If any of its predictions are wrong, there's nowhere to hide. No fudge factors or tweaks are available. On the other hand, a perfectly rigid theory, once it shows significant success, becomes very powerful indeed. Because if it's approximately right and can't be changed, then it must be exactly right!
Salieri's criteria explain why symmetry is such an appealing principle for theory building. Systems with symmetry are well on the path to Salieri's perfection. The equations governing different objects and different situations must be strictly related, or the symmetry is diminished. With enough violations all pattern is lost, and the symmetry falls. Symmetry helps us make perfect theories.
So the crux of the matter is not the number of notes or the number of particles or equations. It is the perfection of the designs they embody. If removing any one would spoil the design, then the number is exactly what it should be. Mozart's answer to the emperor was superb: "Which few did you have in mind, Majesty? "
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Similarly, at first encounter people are sometimes put off by the superficial complexity of fundamental physics. Too many gluons!
But each of the eight color gluons is there for a purpose. Together, they fulfill complete symmetry among the color charges. Take one gluon away, or change its properties, and the structure would fall. Specifically, if you make such a change, then the theory formerly known as QCD begins to predict gibberish; some particles are produced with negative probabilities, and others with probability greater than 1. Such a perfectly rigid theory, one that doesn't allow consistent modification, is extremely vulnerable. If any of its predictions are wrong, there's nowhere to hide. No fudge factors or tweaks are available. On the other hand, a perfectly rigid theory, once it shows significant success, becomes very powerful indeed. Because if it's approximately right and can't be changed, then it must be exactly right!
Salieri's criteria explain why symmetry is such an appealing principle for theory building. Systems with symmetry are well on the path to Salieri's perfection. The equations governing different objects and different situations must be strictly related, or the symmetry is diminished. With enough violations all pattern is lost, and the symmetry falls. Symmetry helps us make perfect theories.
So the crux of the matter is not the number of notes or the number of particles or equations. It is the perfection of the designs they embody. If removing any one would spoil the design, then the number is exactly what it should be. Mozart's answer to the emperor was superb: "Which few did you have in mind, Majesty?" style="width:100%;margin:20px 0;"/>