Comment encourager des physiciens (jeunes ou vieux, apprentis ou chevronnés) à s'intéresser à la géométrie non commutative (GNC)?
Peter Shor says:Matt: you say “If you think you have better ideas, then please join the fray!”Alain Connes has tried to do precisely that with his non-commutative geometry. He has been completely ignored by the physics community. It may be that his ideas don’t work (this wouldn’t be the first time a Fields-medal-winning mathematician has been wrong about things), but I have not found anyone who is able to explain why they don’t work. I would love to hear a good explanation for why these ideas have been ignored...
May 28, 2013 at 3:19 pm
Do you really think that Connes’ ideas are being ignored because this fields medalist overlooked something that every 3rd year graduate student recognizes? That the entire community has evaluated his ideas and decided they can’t lead anywhere? See Peter Shor’s comment about the fact that no one can give him a good explanation for why Connes’ ideas aren’t being pursued. How come nobody at the IAS, Harvard, etc. is working on alternatives to string theory? Why aren’t new PhDs at American universities writing dissertations about Connes’ ideas?
May 28, 2013 at 4:00 pm
I don’t think that its a valid objection that the mathematics Connes is applying/developing is difficult (I think that “extremely mathematically inaccessible” is an exaggeration): isn’t it rather conceivable that what theoretical physics needs now is a complete change in perspective and that such a change might very well involve new mathematics? And by way, people like Thomas Schucker have done much work to make the noncommutative framework of Connes’ more accessible to physicists.
May 28, 2013 at 4:06 pm
The biggest obstacle to attracting more people to work on this stuff is that C&C predicted a Higgs at ~180 GeV. At the time, it was claimed that this was a make-or-break prediction. (Maybe things have changed there; I don’t know.)A secondary problem is that it’s difficult for an outsider to tell whether the spectral action principle is actually a deep physical principle or just a clever notation in which nearly any QFT can be expressed. It’s an appealing idea and C&C have claimed that the non-commutative geometries which can reduce to the Standard Model are highly constrained. But it takes more expertise than I have to tell what assumptions they are really making. No-go theorems in QFT tend to have loopholes you can drive a bus through.
May 28, 2013 at 4:37 pmThe failed Higgs prediction of Connes’ was perhaps sold too hard – if you read his recent papers the Higgs mass is not a problem for his approach.
To me, the interesting point about Connes’ work is that the entire SM couple to GR is formulated as a single gravitational theory – with the entire gauge sector arising through inner automorphisms (including the Higgs sector). So probably Einstein would have been thrilled by this. There are challenges, of course, but I think its a very interesting change of perspective that deserves attention. The fact that the SM fits into this framework is not trivial.
May 28, 2013 at 5:29 pm
It seems to me that string theory grew as a field as more and more intelligent people thought about the issues in it. To expect a single person such as Lisi or Connes to invent a fully developed, alternative BEFORE receiving input from the lager community is simply preposterous. That there are flaws in their work should be expected, as they haven’t had the benefit of having dozens or hundreds of other people helping to refine their ideas. The physics community should exhibit some more openness about pursuing non-stringy ideas.
Instead of looking for the magic effective operator in a vast landscape randomly (Nature/God will select/choose the good one), may be courageous model-building physicists (dépités mais pas décapités/dismayed but not beheaded ;-) could use and test the hypothetical educated guess from algebraic constraints of the non-commutative geometric framework? Anyway it could be that the naturalness paradigm in "standard" quantum field theory living on a Minkowski space-time is heuristically obsolete and it is required to understand better the compass role of the spin to blend somehow 4D-spacetime and internal gauge degrees of freedom before contemplating any super-space and extra-dimensions...
laboussoleestmonpays, commentaire au billet A kingdom for a scale, 13/08/2013
(On signale en passant la référence shakespearienne du titre du billet de Jester qui résonne rétrospectivement à nos oreilles avec la formule de D. Kastler évoquée récemment dans un billet d'un autre blog ;-)