This basic idea has been floating around in quantum gravity circles for a while, but Hossenfelder's take is more cogent and careful than many of these attempts. Her model is basically a superdeterministic one.
I present a simple argument for why a fundamental theory that unifies matter and gravity gives rise to what seems to be a collapse of the wavefunction. The resulting model is local, parameter-free and makes testable predictions.
Sabine Hossenfelder, "How Gravity Can Explain the Collapse of the Wavefunction" arXiv:2510.11037 (October 13, 2025).
The conclusion states:
I have shown here how the assumption that matter and geometry have the same fundamental origin requires the time evolution of a quantum state to differ from the Schr¨odinger equation. This has the consequence that the ideal time evolutions which minimise the action are those with end states that are to good approximation classical. We can then identify these end states with the eigenstates of the measurement device.
This new model therefore explains why quantum states seem to ‘collapse’ into eigenstates of the measurement observable, and how this can happen while preserving locality. Since the collapse process is governed by quantum gravitational contributions whose strength is known, the resulting model is parameter free.
Collapse happens in this model whenever the accumulated phase difference between dislocated branches, τm|Φ12|, exceeds ∼ 1. The model’s phenomenology—notably the collapse itself—can be tested in roughly the same parameter range as other tests of the weak field limit of quantum gravity.
3 comments:
do you have any opinions of GraviGUT unification ?
follow up to SU2 weak -gravity unification
arXiv:2510.11674 (hep-th)
[Submitted on 13 Oct 2025]
GraviGUT unification with revisited Pati-Salam model
Stephon Alexander, Bruno Alexandre, Michael Fine, João Magueijo, Edžus Nākums
We propose a graviGUT unification scheme based on the simple orthogonal group that resolves the chiral duplication of weak isospin in Pati--Salam models. In the conventional framework, the unobserved second chiral is typically removed by ad hoc high-energy scale breaking. Here we instead \emph{geometrize} it: one factor is identified with a chiral half of the Lorentz group, so it belongs to gravity rather than to an additional weak force. This identification becomes natural inside , where the algebra decomposes as . We construct a parity-symmetric chiral action that, upon breaking \emph{dynamically} selects one chirality: the surviving Yang--Mills factor is identified with , while the opposite chirality persists as the gravitational chiral connection. These lead to concrete phenomenological handles, including graviton and weak-boson vertices with the other fundamental forces in and and parity-sensitive gravitational-wave signatures, that distinguish the construction from both traditional Pati--Salam and larger, less economical unifications.
Comments: 9 pages
Subjects: High Energy Physics - Theory (hep-th); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Phenomenology (hep-ph)
This GraviGUT paper develops something that I thought about. Pati-Salam has as its gauge group SU(4) x SU(2)L x SU(2)R, and I wondered if the SU(2)R could be used as Ashtekar gravity. The problem is that in orthodox Pati-Salam, you get standard model hypercharge U(1)Y (which is an ingredient of electromagnetic U(1)em) from SU(2)R, and I doubted that you could do this while using SU(2)R as the gravitational connection too.
I even mentioned this to GPT-5 a month or two ago, and it agreed with me. :-) It points out that in this paper, U(1)em is taken directly from SU(4), with no contribution from SU(2)R, and expresses doubt that the fermions will have the right properties in this case.
is this graviGUT unification scheme by Stephon Alexander violate the Coleman–Mandula theorem? as for fermions, could this graviGUT unification scheme include octonions by Fuery and Baez et al
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