An op-ed article in the New York Times notwithstanding, string theory is still a failure.
The claim is that if it hasn't been experimentally disproven, and it is mathematically beautiful, we should study it. But, of course, you can't experimentally disprove it, because there isn't even a version of it that is suggested at the one that actually explains our reality.
The near definitive ruling out of supersymmetry which most scholars see as a precondition for it and low energy approximation of it doesn't help. The dubiousness of a Majorana neutrino theory doesn't help either. Its reliance of theories that only work in an anti-de Sitter universe which we don't live in also fails to recommend it. And, its claimed need for ten or eleven dimensions, in a four dimensional world, has not found satisfactory solutions.
Woit further develops this theme.
mitchell porter is a believer
ReplyDeleteI'll let him speak for himself. His views are quite a bit more nuanced than yours.
ReplyDeletewhat is your favorite uv-complete qg and bsm?
ReplyDeleteMy favorite BSM or at least not widely accepted physics ideas are: Deur's approach to gravity (with no dark matter or dark energy) or something similar which could permit a quantum gravity extension but wouldn't have to, the idea of QCD squared/double copy as a path to tractable quantum gravity math, conformal invariance as a path to a DM/DE free universe, the Mirror Universe cosmology with a pre-Big Bang anti-universe, a W boson and self-interaction driven source for neutrino masses and for the masses of the fundamental SM particles (extending Koide's rule and the LC&P relation), the possibility of a maximum mass-energy density to match the maximum speed limit of the universe, and the possibility that sphalerons are a non-physical possibility because the conditions to create them can't arise even though the equations permit them. I'm also curious how problematic spin-2 massless gravitons in a space-time that is merely Minkowski space rather than the space-time of GR would actually turn out to be (I suspect that the problems are overstated but I don't know that). I also like equations of gravity that are put in a force form analogous to Newtonian gravity and Maxwell's equations with extra terms, as opposed to the Einstein Field Equations hydrodynamic flow form that can impair understanding despite being very simply on their face. I think that a fairly small number of achievable within my lifetime developments could greatly reduce the number of experimentally determined parameters in the SM + GR. I think that all sorts of popular BSM models from SUSY to string theory to extra Higgs doublets to see-saw neutrino mass to Majorana neutrino mass to dark matter to dark energy to cosmological inflation to preons to fourth generation fundamental fermions, to extra fundamental bosons are probably all inconsistent with reality. I think that it still isn't impossible that the Higgs boson is some sort of superposition of the W+, W-, and Z bosons and the photon. I think that there is room to improve our interpretation and understanding of QM. I think that there is a path we haven't found yet to be profoundly more efficient in how we do QCD calculations. I'm intrigued by graviweak unification (which also ties into Woit's Euclidean spinors and right handed space-time concepts). I'm skeptical of physical theories with more than 3+1 space-time dimensions and even more skeptical of those with more than five. I'm intrigued by matter and locality and dimensionality being emergent concepts as in most loop quantum gravity theories. I am prone to favor ditching causality rather than locality or realism, knowing from quantum mechanics that you can't have all three. Superdeterminism is interesting.
ReplyDeleteI'm also quite interesting in how adding quantum gravity to the three SM fundamental forces (plus the Higgs field) would change the running of the experimentally determined constants of the SM at high energies. I think that there are no sterile/right handed neutrinos. I think that there are no non-standard neutrino interactions, and that there is no X17 particle. I think that CPT symmetry and conservation of mass-energy in end states (as opposed to virtual particle SM states) are absolute. I think that either virtual or real by vanishingly rare violations of Lorenz invariance (i.e. of the speed of light speed limit) might be possible due to the way that the path integral of the photon propagator is calculated. I like thinking of anti-matter as matter particles moving backward in time. I also think that the seeming tolerance of Lorenz invariance violation in the photon propagator might be a hint of a discrete space-time in which the distance from point A to point B by different paths might actually not be exactly the same due to the nature of the links between nodes in the a discrete space-time network, although at extremely tiny scales. I don't think that gravitons are massive. A think that charged lepton universality might be almost but not perfectly true due to W boson interactions with neutrinos which do not display universality in their W boson interactions. I'm intrigued by the idea that CP violation in the SM CKM and PMNS matrixes might have a source that manifests in these matrixes but is fundamentally distinct from transitions from one quark to another or one lepton to another via a W boson. I think that the W boson is much more deserving of the title "the God particle" than the Higgs boson that has claimed that title. I'm intrigued by Mach's principle and emergent gravity theories like Verlinde's, which would be truly awesome if they could be made to work. I am curious about dimensionless formulations of the coupling constant of gravity (usually handled with the dimensionful Newton's constant). I have some suspicions that we still can't cleanly predict all possible hadrons and their properties because we are missing some important QCD principle that explains what blends of simple valence quark structures do and don't happen and why. I am interested in the very standard model development of general parton distribution functions from first principles. I think that with the little bit more theory and cleverness that it might be possible to reduce the number of degrees of freedom in the CKM and PMNS matrixes from the current four each (which is the most that a 3x3 matrix that codes probabilities of transitions from three things to three things can have) to two or three free parameters.
ReplyDeleteI think that baryon number and lepton number may be absolute unbreakable symmetries (related to the possible barrier to sphalerons due, e.g., to a maximum mass-energy density).
ReplyDeleteI don't think that there are new physics hiding between the energies of the LHC and the GUT scale. I don't think that there are any primordial black holes of less than 3 stellar masses left today, even if there might once have been some in the very early universe that weren't a meaningful source of dark matter phenomena. I don't think that isotropic and homogeneous is a good description of the observable universe at the largest scales.
ReplyDeleteI don't dismiss asymptotic freedom gravity theory out of hand although it isn't my favorite.
ReplyDeletei was just about to ask about loop quantum gravity cdt twister etc. octonions,
ReplyDeletex17 research results are taking forever
My opinion on string theory is that they need to aim at a different kinds of phenomenology, e.g. standard model all the way to Planck scale, and correctness of MOND at galactic scales. There may also need to be theoretical innovations.
ReplyDeletemitchell porter so do you believe in susy, 10 dimensions gut? what about anti-ds and swamp regards
ReplyDeleteAnything could be true at Planck scale.
ReplyDeleteis it fair to say mitchell porter is a believer
ReplyDelete