I would add at least a couple more.
There are false problems that ask "why doesn't the universe act like I think (for no good reason) that it should?" This includes the hierarchy problem, the strong CP problem, the baryon asymmetry of the universe, and all research invoking the concept of "naturalness."
And, there are contradictory data problems, where one asks why multiple measurements of the same thing (in your current theory) are producing irreconcilable results. These have included the proton radius puzzle, the data based calculation of muon g-2, the measurement of the mean lifetime of unbound neutrons, the reanalysis of CDF data to determine the W boson mass that produced an anomalous result, and the Hubble tension. Usually, in these cases, the answer is that somebody screwed up in one or both of the experiments (at a minimum by overstating the uncertainty in the result), or the theoretical analysis involved, but sometimes, the theory that said the measurements should be the same was wrong.
Quantum modified inertia: an application to galaxy rotation curves
ReplyDeleteAuthors: Jonathan Gillot
Abstract: This study explores the field of modified inertia through a novel model involving maximal and minimal acceleration bounds. A principle of dynamics is developed within special relativity and has direct implications in astrophysics, especially for galaxy rotation curves. The presence of a minimal acceleration significantly reduces the amount of dark matter required to account for these curves. The model presented here is however conceptually different from fiduciary Modified Newtonian Dynamics (MOND). The modified inertia with the minimal acceleration bound closely matches with many observed galaxy rotation curves and the radial acceleration relation, showing a better agreement than MOND in the m s regime. Additionally, the minimal acceleration is predicted to evolve with redshift. △ Less
Interesting, the main QI guy is someone different. https://physicsfromtheedge.blogspot.com/
ReplyDeleteProbing the nature of gravity in the low-acceleration limit: wide binaries of extreme separations with perspective effects
ReplyDeleteAuthors: Youngsub Yoon, Yong Tian, Kyu-Hyun Chae
Abstract: Recent statistical analyses of wide binaries have revealed a boost in gravitational acceleration with respect to the prediction by Newtonian gravity at low internal accelerations m\,s . This phenomenon is important because it does not permit the dark matter interpretation, unlike galaxy rotation curves. We extend previous analyses by increasing the maximum sky-projected separation from 30 to 50 kilo astronomical units (kau). We show that the so-called ``perspective effects'' are not negligible at this extended separation and, thus, incorporate it in our analysis. With wide binaries selected with very stringent criteria, we find that the gravitational acceleration boost factor, , is (from ) at Newtonian accelerations m\,s , corresponding to separations of tens of kau for solar-mass binaries. At Newtonian accelerations m\,s , we find ( ). For all binaries with m\, from our sample, we find ( ). These results are consistent with the generic prediction of MOND-type modified gravity, although the current data are not sufficient to pin down the low-acceleration limiting behavior. Finally, we emphasize that the observed deviation from Newtonian gravity cannot be explained by the perspective effects or any separation-dependent eccentricity variation which we take into account. △ Less
Submitted 17 July, 2025; originally announced July 2025.
Thanks for the heads up. I've been traveling to visit family since Thursday, so I might have missed it otherwise.
ReplyDeleteok, when you get back could i have your opinion, or Mitchel Porter on this latest paper
ReplyDeletearXiv:2504.16465 (hep-th)
[Submitted on 23 Apr 2025]
Octonions, complex structures and Standard Model fermions
Kirill Krasnov
This article is a write-up of the talk given in one of the mini-symposia of the 2024 European Congress of Mathematicians. I will explain some basics of the representation theory underlying Spin(10) and SU(5) Grand Unified Theories. I will also explain the characterisation of the Standard Model gauge group G_SM as a subgroup of Spin(10) that was developed in [1]. Thus, the symmetry breaking required to obtain G_SM can be seen to rely on two suitably aligned commuting complex structures on R10. The required complex structures can in turn be encoded in a pair of pure spinors of Spin(10). The condition that the complex structures are commuting and suitably aligned translates into the requirement that the respective pure spinors are orthogonal and that their sum is again a pure spinor. The most efficient description of spinors, and in particular pure spinors of Spin(10) is via the octonionic model of the latter, and this is how octonions enter the story.
2 Kirill Krasnov
as the one that relies on two suitably aligned complex structures in R10. Also pure
spinors and the octonionic model of Spin(10) are going to play an important role.
We start, in Section 2, with the description of the elementary particle content
of the Standard Model (SM) of particle theory. As is was known since the 70’s,
i.e. almost immediately after the SM was formulated, this particle content arises
very naturally if one embeds the SM gauge group 𝐺SM into a larger gauge group
such as SU(5) or Spin(10). Particle physicists usually refer to the later as SO(10).
However, since spinors are going to play a very important role in our description
of the symmetry breaking, we will refer to the relevant gauge group as Spin(10), to
justify our usage of the spinor representations of the latter.
Section 3 is central to our presentation. Here we remind the reader the concept of
the complex structure on a vector space, and also describe what happens when one
has two commuting complex structures. We then describe the well-known relation
between (complex lines of) pure spinors of Spin(2𝑛) and complex structures on R2𝑛.
We end this section with Theorem 1detailing the characterisation of 𝐺SM ⊂ Spin(10)
that was developed in [1].
Section 4 describes the octonionic model of Spin(10), in which Weyl spinors
become identified with 2-component columns with entries in complexified octonions
OC. This model allows for a very explicit description of pure spinors of Spin(10),
detailed in Proposition 1. We then explicitly describe the two pure spinors that are
relevant for the symmetry breaking Spin(10) → 𝐺SM. We end with some discussion.
There is a large literature on the topics of this contribution. Some of the most
relevant references are [3]-[17]
2 Particle content of the SM, SU(5) and Spin(10) unification
2.1 Particles
Particles of the Standard Model come in three generations that are exact copies of
each other as far as their 𝐺SM transformation properties are concerned. We will only
consider a single generation in this exposition. For readers without background in
physics we remind that the factors of the SM gauge group 𝐺SM have the following
purpose. The SU(3) factor describes the strong force, which is the force that is
responsible for keeping together the constituents (quarks) of particles such as proton
and neutron (making up the atomic nuclei). The SU(2) factor describes the weak
force that is behind nuclear reactions and the atomic bomb. Finally, the U(1) factor,
or rather its certain combination with U(1) ⊂ SU(2) describes the electromagnetic
force
octonions acting on weyl pure spinors in a complex structures gives rise to the standard model (SO 10) including three generations of fermions
Kirill Krasnov is someone whose work in general interests me. But I have the same problem I have e.g. with algebrologists like Cohl Furey - I don't understand how to retain the connection with division algebras, when the time comes to do physics (e.g. in dynamical equations).
ReplyDeleteWhat I mean by this: Krasnov, Furey, etc will make a mapping or association, between objects in the standard model, and something to do with octonions. But as far as I know, we can't actually write the equations in terms of octonions, we can't do standard model calculations in terms of octonions. I certainly don't know how to write an octonionic equation for the dynamical breaking of grand unification symmetries, for example.
Murat Gunaydin recently posted a talk from 10 years ago, in which he *does* talk about a genuinely octonionic quantum theory:
https://arxiv.org/abs/2507.17938
This is the quantum theory associated with the "exceptional Jordan algebra". John Baez talked about this on Physics Forums, I think... If you could express any of these ideas, as occurring for a particular branch of the J3(O) quantum theory, then you really would have given the octonionic association a physical meaning.
Despite these reservations, I do think works like these are very worthwhile, they add to the tapestry of mathematical knowledge surrounding the options for physics, and may yet translate to physics.
I'll add that for several months, the main theory I've studied has been Eric Weinstein's extremely controversial Geometric Unity theory, which is in this general territory of mutant modern forms of grand unification, but also has a lot of other stuff going on.
I mentioned Geometric Unity because some of Krasnov's other work overlaps with it. GU deals with spin groups in a 14-dimensional space and so does Krasnov (he has papers on getting the standard model from Spin(7,7) and Spin(11,3), some of which also explore the octonionic aspect).
ReplyDeletethanks so are octonions acting on weyl pure spinors in a complex structures imply that weyl pure spinors are similar to preons or even strings, fundamental objects to get the standard model
ReplyDelete