Monday, September 24, 2007
Fallacies from string theory
The issue of Physics World on string theory contains much material that is not only wrong, but obviously incorrect. Perhaps the most spectacular is the cosmological constant. It is trivially 0. Putting it in Einstein's equation sets a variable equal to a constant. A variable cannot equal a constant. Even a high school student knows that. There is no cosmological constant, which is unfortunate. If there were gravitation would have a fascinating property. A gravitational wave would be detected an infinitely long time before it is emitted. See the MRPG book (with further discussion in OAIU) or those who want to show this themselves can use the example in MTW. It is amazing that there have been so many esoteric explanations for such a trivial mistake. This is something that sociologists and philosophers of science should study, as should psychiatrists. In physics if a theory makes a wrong prediction just say that it has not advanced to the stage at which it can make predictions. Despite what its adherents say string theory has made a prediction --- the dimension, and that is wildly wrong (which is a reason string theory is so attractive). What is worse it has long been known that physics would be impossible in any dimension but 3+1, quite boring since it agrees with reality. See the OAIU book (and also GTFQM) for a rigorous proof. String theory has been proven with mathematical rigor to be impossible, thus physicists are quite enthusiastic about it. Of course string theory has no rationale (like Bush's Iraq policy) except for the excitement, wishful thinking and daydreaming it stimulates. The proper criteria for a theory in physics are not experiment, not mathematics, but wishful thinking and fantasy. With that criteria it does quite will. (The requirement for truth is tricky. Theories can be complete nonsense but necessary as classical physics and Bohr's theory show. See the OAIU book for discussion. But string theory does not fit into that either. Nor is it simple. It is wildly complicated and hideously ugly. Perhaps that is why so many physicists are so obsessed with it. Occam would be furious that anyone is considering such a theory.) It is strange that anyone would consider investing in a theory that has been proven to be nonsense. Of course no physics journal would consider publishing the proof that the dimension must be what experiment gives. That would spoil all the fun. Physicists are very concerned about ethics. Yet they find it perfectly acceptable to allow people to waste their careers and much public money working on something that is known wrong. Nor do they care about misleading the public (look at the best selling books that are nonsense) which will eventually undermine the support of science. (Of course no one cares about academic freedom. Those who do not want to waste their careers producing nonsense do not have that freedom since they are not allowed to know that what they are doing must be wrong.) As Goldhaber points out this is all quite unscientific. So why isn't it being fought more rigorously? Rather than fighting it "physicists" accept it enthusiastically! Another example of physicists' desire to find the most esoteric, complicated, convoluted explanation for simple results is quantum mechanics. Why nature must be quantum mechanical is almost trivial. See the GTFQM and OAIU books, plus QM,QFT. Then there is the daydream that string theory will produce a quantum theory of gravity. This ignores the fact that there is already one, the only possible one since it is required by geometry: GR. See MRPG. Where did the confusion that it is not quantum mechanical come from? It is completely quantum mechanical, including having uncertainty principles. What more does anyone want? But GR, while correct, isn't much fun. David Gross says we still don't know what string theory is. Sure we do. It is complete nonsense. The best thing that could be done to advance physics would be to bring Occam back to life. For further discussion and other problems with these see the books and my blog.