(no subject)
(Obligatory squee at the time and how FAST it seems to be passing: AIEEEIEIEIE!)
The thing about SoB Crit is that it's so timely. As found in this article from the New Yorker:
It is strange to think that such sordid motives might affect something as pure and objective as physics. But these are strange days in the discipline. For the first time in its history, theory has caught up with experiment. In the absence of new data, physicists must steer by something other than hard empirical evidence in their quest for a final theory. And that something they call “beauty.” But in physics, as in the rest of life, beauty can be a slippery thing.
The gold standard for beauty in physics is Albert Einstein’s theory of general relativity. What makes it beautiful? First, there is its simplicity. In a single equation, it explains the force of gravity as a curving in the geometry of space-time caused by the presence of mass: mass tells space-time how to curve, space-time tells mass how to move. Then, there is its surprise: who would have imagined that this whole theory would flow from the natural assumption that all frames of reference are equal, that the laws of physics should not change when you hop on a merry-go-round? Finally, there is its aura of inevitability. Nothing about it can be modified without destroying its logical structure. The physicist Steven Weinberg has compared it to Raphael’s “Holy Family,” in which every figure on the canvas is perfectly placed and there is nothing you would have wanted the artist to do differently.
[...]
Is physics, then, going postmodern? (At Harvard, as Smolin notes, the string-theory seminar was for a time actually called “Postmodern Physics.”) The modern era of particle physics was empirical; theory developed in concert with experiment. The standard model may be ugly, but it works, so presumably it is at least an approximation of the truth. In the postmodern era, we are told, aesthetics must take over where experiment leaves off. Since string theory does not deign to be tested directly, its beauty must be the warrant of its truth.
In the past century, physicists who have followed their aesthetic sense in the absence of experimental data seem to have done quite well. As Paul Dirac said, “Anyone who appreciates the fundamental harmony connecting the way Nature runs and general mathematical principles must feel that a theory with the beauty and elegance of Einstein’s theory has to be substantially correct.” The idea that “beauty is truth, truth beauty” may be a beautiful one, but is there any reason to think it is true? Truth, after all, is a relationship between a theory and the world, whereas beauty is a relationship between a theory and the mind. Perhaps, some have conjectured, a kind of cultural Darwinism has drilled it into us to take aesthetic pleasure in theories that are more likely to be true. Or perhaps physicists are somehow inclined to choose problems that have beautiful solutions rather than messy ones. Or perhaps nature itself, at its most fundamental level, possesses an abstract beauty that a true theory is bound to mirror. What makes all these explanations suspect is that standards of theoretical beauty tend to be ephemeral, routinely getting overthrown in scientific revolutions. “Every property that has at some date been seen as aesthetically attractive in theories has at other times been judged as displeasing or aesthetically neutral,” James W. McAllister, a philosopher of science, has observed.
The closest thing to an enduring mark of beauty is simplicity; Pythagoras and Euclid prized it, and contemporary physicists continue to pay lip service to it. All else being equal, the fewer the equations, the greater the elegance. And how does string theory do by this criterion? Pretty darn well, one of its partisans has facetiously observed, since the number of defining equations it has so far produced remains precisely zero. At first, string theory seemed the very Tao of simplicity, reducing all known particles and forces to the notes of a vibrating string. As one of its pioneers commented, “String theory was too beautiful a mathematical structure to be completely irrelevant to nature.” Over the years, though, it has repeatedly had to be jury-rigged in the face of new difficulties, so that it has become a Rube Goldberg machine-or, rather, a vast landscape of them. Its proponents now inveigh against what they call “the myth of uniqueness and elegance.” Nature is not simple, they maintain, nor should our ultimate theory of it be. “A good, honest look at the real world does not suggest a pattern of mathematical minimality,” says the Stanford physicist Leonard Susskind, who seems to have no regrets about string theory’s having “gone from being Beauty to the Beast.”
If neither predictive value nor beauty explains the persistence of string theory, then what does?
The thing about SoB Crit is that it's so timely. As found in this article from the New Yorker:
It is strange to think that such sordid motives might affect something as pure and objective as physics. But these are strange days in the discipline. For the first time in its history, theory has caught up with experiment. In the absence of new data, physicists must steer by something other than hard empirical evidence in their quest for a final theory. And that something they call “beauty.” But in physics, as in the rest of life, beauty can be a slippery thing.
The gold standard for beauty in physics is Albert Einstein’s theory of general relativity. What makes it beautiful? First, there is its simplicity. In a single equation, it explains the force of gravity as a curving in the geometry of space-time caused by the presence of mass: mass tells space-time how to curve, space-time tells mass how to move. Then, there is its surprise: who would have imagined that this whole theory would flow from the natural assumption that all frames of reference are equal, that the laws of physics should not change when you hop on a merry-go-round? Finally, there is its aura of inevitability. Nothing about it can be modified without destroying its logical structure. The physicist Steven Weinberg has compared it to Raphael’s “Holy Family,” in which every figure on the canvas is perfectly placed and there is nothing you would have wanted the artist to do differently.
[...]
Is physics, then, going postmodern? (At Harvard, as Smolin notes, the string-theory seminar was for a time actually called “Postmodern Physics.”) The modern era of particle physics was empirical; theory developed in concert with experiment. The standard model may be ugly, but it works, so presumably it is at least an approximation of the truth. In the postmodern era, we are told, aesthetics must take over where experiment leaves off. Since string theory does not deign to be tested directly, its beauty must be the warrant of its truth.
In the past century, physicists who have followed their aesthetic sense in the absence of experimental data seem to have done quite well. As Paul Dirac said, “Anyone who appreciates the fundamental harmony connecting the way Nature runs and general mathematical principles must feel that a theory with the beauty and elegance of Einstein’s theory has to be substantially correct.” The idea that “beauty is truth, truth beauty” may be a beautiful one, but is there any reason to think it is true? Truth, after all, is a relationship between a theory and the world, whereas beauty is a relationship between a theory and the mind. Perhaps, some have conjectured, a kind of cultural Darwinism has drilled it into us to take aesthetic pleasure in theories that are more likely to be true. Or perhaps physicists are somehow inclined to choose problems that have beautiful solutions rather than messy ones. Or perhaps nature itself, at its most fundamental level, possesses an abstract beauty that a true theory is bound to mirror. What makes all these explanations suspect is that standards of theoretical beauty tend to be ephemeral, routinely getting overthrown in scientific revolutions. “Every property that has at some date been seen as aesthetically attractive in theories has at other times been judged as displeasing or aesthetically neutral,” James W. McAllister, a philosopher of science, has observed.
The closest thing to an enduring mark of beauty is simplicity; Pythagoras and Euclid prized it, and contemporary physicists continue to pay lip service to it. All else being equal, the fewer the equations, the greater the elegance. And how does string theory do by this criterion? Pretty darn well, one of its partisans has facetiously observed, since the number of defining equations it has so far produced remains precisely zero. At first, string theory seemed the very Tao of simplicity, reducing all known particles and forces to the notes of a vibrating string. As one of its pioneers commented, “String theory was too beautiful a mathematical structure to be completely irrelevant to nature.” Over the years, though, it has repeatedly had to be jury-rigged in the face of new difficulties, so that it has become a Rube Goldberg machine-or, rather, a vast landscape of them. Its proponents now inveigh against what they call “the myth of uniqueness and elegance.” Nature is not simple, they maintain, nor should our ultimate theory of it be. “A good, honest look at the real world does not suggest a pattern of mathematical minimality,” says the Stanford physicist Leonard Susskind, who seems to have no regrets about string theory’s having “gone from being Beauty to the Beast.”
If neither predictive value nor beauty explains the persistence of string theory, then what does?