Sunday, January 06, 2013

Higgs and Dyson papers

From PNAS commentary on Dyson paper
Catching up on some scientific reading:

  • Iterated Prisoner’s Dilemma contains strategies that dominate any evolutionary opponent is a paper by William H. Press and Freeman Dyson in PNAS that, remarkably, discovers a fundamental new property of Iterated Prisoner's Dilemma games. It turns out that there are strategies whereby "a player X ...can (i) deterministically set her opponent Y’s score, independently of his strategy or response, or (ii) enforce an extortionate linear relation between her and his scores. Against such a player, an evolutionary player’s best response is to accede to the extortion. Only a player with a theory of mind about his opponent can do better, in which case Iterated Prisoner’s Dilemma is an Ultimatum Game." (see also commentary here).

    This point about "Theory of Mind" is very interesting and important.  It's a demonstration in microcosm of why the evolution of a Theory of Mind is so important. Similar considerations also push for the evolution of freewill if defined as "the ability to make decisions that cannot be reliably predicted by other creatures with which you interact".

    And of course it's pretty impressive to make a major contribution to a new field when you are 88 - this may be a record and I'd be interested to know who has published a Nature/Science/PNAS paper at a more advanced age.  He is one of the last working scientists to remember Einstein well, they overlapped at the IAS from 1953 to 1955.
  • The Higgs Bosons paper in Science. I hadn't appreciated just how intricate and indirect the observation of the Higgs is. The authors all make the point in different ways that the Higgs points to Supersymmetry,  ("Without new phenomena, quantum loop processes would drive the predicted Higgs boson mass far above the highest energy scale at which the SM is valid." (ATLAS) "It is known that quantum corrections make the mass of a fundamental scalar particle float up to the next highest physical mass scale currently known, which, in the absence of extensions to the SM, is as high as 1015 GeV...In the minimal supersymmetry model, five types of Higgs bosons are predicted to exist. Furthermore, the lightest stable neutral particle of this new family...could be the particle constituting dark matter. If, as conjectured, such particles are light enough, they ought to reveal themselves at the LHC." (summary article). 

    As readers of this blog will know I'm very sceptical about string theory as physics (it's clearly very deep and interesting mathematics) and I can't help feeling that the idea of QM corrections making a mass "float up" almost 12 orders of magnitude is extrapolating ridiculously far. It seems more likely that there will be an adjustment to the corrections, based perhaps on  information-theoretic considerations limiting the number of iterations of correction or maybe from quantisation of space.  But I'm not competent to go into the mathematics. (I do know that Supersymmetry doesn't necessarily imply String Theory, but they are close relatives).

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