Thursday, October 24, 2013

Death of SUSY

Tom Siegfried writes in Science News about his belief in physics ideas in spite of the evidence:
SUSY is shorthand for supersymmetry, the odds-on favorite to solve many of the mysteries about the physical world that have stumped theorists for decades. Supposedly the LHC should produce actual evidence for SUSY, but it hasn’t. And so some physicists have begun to declare SUSY dead, or at least on life-support. Consequently, they say, physics now faces one of the greatest crises in its history. A typical lament, from one recent paper:

“After three years of very successful experimental work at Large Hadron Collider (LHC) at CERN, theoretical physics is apparently in the greatest crisis in its history.” The experimental findings “have nearly eliminated supersymmetry as a possible physical theory. It seems inevitable that we have to face the Nightmare Scenario (i.e. no signs of new physics at LHC) and the unprecedented collapse of decades of speculative work.”

In September, Neil Turok, director of the Perimeter Institute in Canada, squirted lighter fluid into the flames during a lecture to students.  “Theoretical physics is at a crossroads right now. In a sense we’ve entered a very deep crisis,” he said. SUSY (and other theories) predicted that the LHC would find new particles. “And they’re not there,” Turok declared. “And so to a large extent, the theories have failed.”

Well, maybe. But it might not really be so bad. Perhaps a little context is in order, starting with why physicists loved SUSY so much in the first place and then investigating the reasons for concern a little more deeply. There may turn out to be various ways the play could end without everybody having to die.

First of all, supersymmetry seems like such a good idea to physicists because symmetry even without the super was so successful. (After all, isn’t a supernova better than a nova? Supermodel better than a model? Superman better than Clark Kent?) Symmetry showed its power in Einstein’s theory of relativity, for example, and later on in the development of the modern theory of particles and forces, the standard model (or as Nobel laureate Frank Wilczek likes to call it, the Theory of Matter).

This is the nightmare for theoretical physicists. We got a very nice theory of everything in the 1970s, and since then all the big shots have been telling us that the theory must be wrong and we need to spend tens of billions of dollars building accelerators to prove it.

So far, the LHC has only confirmed the Standard Model of the 1970s.

Note how all these guys go out of their way to credit Einstein, even when he has nothing to do with the subject. Einstein did not discover the power of symmetry in relativity. The symmetry group is called the Lorentz group, because Poincare named it before Einstein ever wrote a paper on relativity.
Einstein was particularly skillful when it came to symmetry. His theory of relativity embodies the principle that the laws of physics stay the same no matter how you move.
No it was Lorentz who figured out how the laws of electromagnetism stayed the same no matter how you move, and Poincare who looked for a relativistic gravity by looking for laws invariant under the Lorentz group.

The only symmetry argument that Einstein discovered on his own, as far as I know, was that the inverse Lorentz transformation had the same form. Apparently Lorentz did not notice that in his 1904 paper. Of course Poincare had it all, and had it before Einstein.

Siegfried also believes in the multiverse, but not the Higgs.

Quantum Frontiers names the 10 biggest breakthroughs in physics over the past 25 years. My problem with the list is that several of them have no known relation to the real world: Shor’s Algorithm, Quantum Error Correction (QEC), AdS/CFT, Quantum Teleportation. The first two are pure math and might be realizable if quantum computers were possible, but all attempts have fails. AdS/CFT is math, and is not realizable. Teleportation is an interpretation given to certain experiments, but it is not really teleportation and none of the supposed practical advantages of teleportation have ever been realized.

The blog also promises to list the biggest open problems, including quantum gravity, firewalls, harnessing quantum weirdness, and what is time. I'll have to wait and see what he says, but I do not agree that these are open problems.

No comments:

Post a Comment