Friday, March 09, 2007
when the detractors are away
Now that one detractor is away for the next week and a half, a lot more pro-string blog posts will be written. This, obviously, is one of them.
I explored the physics department at Rutgers yesterday in order to find out about their graduate programs in high energy/string and condensed matter physics. Apparently they only have about a dozen professors and just slightly more graduate students in high energy theory, with only around half of the aforementioned concentrating in string theory. The numbers in condensed matter theory and experiment (each) are about the same as in high energy theory. Even at a very large university with a lot of physics professors, clearly not "everyone" is concentrating in string theory.
So, what is groupthink? I think it's evident that groupthink is a Lie group (additional meaning intended). Not everyone is dropping what they're doing in order to concentrate on some untestable figment of pseudo-mathematicians' collective imagination.
After the LHC is completed, theoretical physics will become more data-driven. The high-energy physicists I talked to seemed very excited over this (understandably) since phenomenology will play a greater role. After the success of the Standard Model and the (electroweak) unification of electromagnetism with the weak nuclear force earned three physicists the Nobel Prize in 1979, there really haven't been too many exciting breakthroughs in experimental physics. Phenomenology- connecting theory with experiment- will become more vital than ever once the LHC is finished, particularly if the Higgs boson or extra dimensions are discovered. The high-energy physicists I talked to considered the "extra dimensions" part highly unlikely, but not impossible. Hopefully the physics job market will prosper with more data coming in... more "phenomenologists" will be required.
So, will the LHC discover anything about "loop quantum gravity"? It was evident- from talking to string theorists yesterday- that they were in fact string theorists; LQG to them was "not serious physics" and "bad for young physicists to get involved in" as opposed to "good quantum gravity" or something more serious like AdS/CFT. I got the impression that the reason why more physicists weren't working on LQG was that it was rife with problems. That didn't surprise me at all. Is string theorists' view of LQG disparaging or reflective of "groupthink", or is it a correct, honest view? I would have to agree with the latter.
String theory is based on the foundations of quantum field theory. If you don't know QFT, you can't do very much string theory. (If you don't know math, you can't learn very much physics, even of the classical variety.) QFT extends beyond quantum mechanics, which is based on linear algebra. I am only an undergrad, so I haven't taken a field theory course yet. However, the problems with LQG are obvious even for someone who hasn't taken QFT or who hasn't been "brainwashed" by pro-string PhD advisors yet :)
Quantum mechanics is the study of quantum states. The wavefunction |psi> is the most important of these (the Schrodinger equation equates E|psi> to H|psi>). A wavefunction evolves in time by the equation e^(-iHt/hbar)|psi(0)> = |psi(t)>. Nothing too complicated there (once you get used to bra-ket notation). But QFT is much harder and requires more abstract mathematical techniques. And string theory is based on this, making it harder still. It is an extension of our present knowledge, not something completely "out there" or "not even science anymore." Its critics (especially the bad science journalists whom I've discussed before) don't see this connection.
I hope the LHC will change that.
¶ 3:38 PM
I explored the physics department at Rutgers yesterday in order to find out about their graduate programs in high energy/string and condensed matter physics. Apparently they only have about a dozen professors and just slightly more graduate students in high energy theory, with only around half of the aforementioned concentrating in string theory. The numbers in condensed matter theory and experiment (each) are about the same as in high energy theory. Even at a very large university with a lot of physics professors, clearly not "everyone" is concentrating in string theory.
So, what is groupthink? I think it's evident that groupthink is a Lie group (additional meaning intended). Not everyone is dropping what they're doing in order to concentrate on some untestable figment of pseudo-mathematicians' collective imagination.
After the LHC is completed, theoretical physics will become more data-driven. The high-energy physicists I talked to seemed very excited over this (understandably) since phenomenology will play a greater role. After the success of the Standard Model and the (electroweak) unification of electromagnetism with the weak nuclear force earned three physicists the Nobel Prize in 1979, there really haven't been too many exciting breakthroughs in experimental physics. Phenomenology- connecting theory with experiment- will become more vital than ever once the LHC is finished, particularly if the Higgs boson or extra dimensions are discovered. The high-energy physicists I talked to considered the "extra dimensions" part highly unlikely, but not impossible. Hopefully the physics job market will prosper with more data coming in... more "phenomenologists" will be required.
So, will the LHC discover anything about "loop quantum gravity"? It was evident- from talking to string theorists yesterday- that they were in fact string theorists; LQG to them was "not serious physics" and "bad for young physicists to get involved in" as opposed to "good quantum gravity" or something more serious like AdS/CFT. I got the impression that the reason why more physicists weren't working on LQG was that it was rife with problems. That didn't surprise me at all. Is string theorists' view of LQG disparaging or reflective of "groupthink", or is it a correct, honest view? I would have to agree with the latter.
String theory is based on the foundations of quantum field theory. If you don't know QFT, you can't do very much string theory. (If you don't know math, you can't learn very much physics, even of the classical variety.) QFT extends beyond quantum mechanics, which is based on linear algebra. I am only an undergrad, so I haven't taken a field theory course yet. However, the problems with LQG are obvious even for someone who hasn't taken QFT or who hasn't been "brainwashed" by pro-string PhD advisors yet :)
Quantum mechanics is the study of quantum states. The wavefunction |psi> is the most important of these (the Schrodinger equation equates E|psi> to H|psi>). A wavefunction evolves in time by the equation e^(-iHt/hbar)|psi(0)> = |psi(t)>. Nothing too complicated there (once you get used to bra-ket notation). But QFT is much harder and requires more abstract mathematical techniques. And string theory is based on this, making it harder still. It is an extension of our present knowledge, not something completely "out there" or "not even science anymore." Its critics (especially the bad science journalists whom I've discussed before) don't see this connection.
I hope the LHC will change that.
¶ 3:38 PM
