Friday, April 12, 2019

Physics Quote Of The Day

String theory is a living proof of the dangers of excessive reliance on non-empirical arguments. It raised great expectations thirty years ago, promising to compute all the parameters of the Standard Model from first principles, to derive from first principles its symmetry group SU(3)×SU(2)×U(1) and the existence of its three families of elementary particles, to predict the sign and the value of the cosmological constant, to predict novel observable physics, to understand the ultimate fate of black holes, and to offer a unique, well-founded unified theory of everything. 
Nothing of this has come true. String theorists, instead, have predicted a negative cosmological constant, deviations from Newton’s 1/r^2 law at sub-millimeters scale, black holes at the European Organization for Nuclear Research(CERN), low-energy super-symmetric particles, and more. All this was false. 
Still, Joe Polchinski, a prominent string theorist, writes that he evaluates the Bayesian probability of string to be correct at 98.5% (!). This is clearly nonsense.
Carlo Rovelli in a paper at a December 2015 string theory conference in Munich, via Not Even Wrong, which also notes that the probability claimed was actually "three sigma" (99.73%), and that with regard to a contribution from physicist Gordon Kane: "As usual with Kane, there’s a string theory “prediction” of the gluino mass (1.5 TeV +/- 10-15%) which has already been falsified."

The situation has not improved in the three years that have elapsed since this conference, although the tides of educated public opinion do seem to be shifting, ever so slightly.


neo said...

Did you ever believe in string theory and when did that belief change?

andrew said...

Yes. When I was in middle school and high school in the late 1980s, I was sure that String Theory would turn out to be real.

Then, I didn't think about the question very much at all as an undergraduate student (despite studying lots of math and physics) and then as a law student and then as a fledgeling lawyer because I had other things on my mind.

I probably started to pay attention to the issue again in the early 2000s. By 2005, when I started sister blog Wash Park Prophet, I was at a minimum agnostic and skeptical about the veracity of String Theory. See I have grown increasingly skeptical of String Theory over time since then, particular in the last two or three years.

neo said...

in the 90s i read Brian Green Elegant Universe to Michio Kaku Beyond Einstein to Stephan Hawking brief moment in time etc

PBS had documentaries on string theory.

I also saw Hawking on star trek next generation, and I saw the Nova documentary on string theory, featuring ed witten.

Brian Green in the documentaries talks about how the LHC may find SUSY particles which shows string theory is on the right track.

sometime i came across Peter Woit's not even wrong and Lee Smolin's the trouble with physics.

well, it's 2019, no SUSY. :(