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Not all physicists think they are incompatible. Mark Hadley [0][1] for example suggests that: "On spacetimes that are not time orientable we construct a U(1) b

Not all physicists think they are incompatible. Mark Hadley [0][1] for example suggests that: "On spacetimes that are not time orientable we construct a U(1) bundle [model of a particle as an asymptotically flat spacetime manifold with a region of non trivial topology where time is not orientable] to measure the twisting of the time axis. This single assumption, and simple construction, gives rise to Maxwell’s equations of electromagnetism, the Lorentz force law and the Einstein-Maxwell equations for electromagnetism coupled to General relativity. The derivations follow the Kaluza Klein theory, but with the constraints required for connections on a U(1) bundle rather than five spacetime dimensions. The non time orientability is seen to justify and constrain Kaluza Klein theories exactly as required to unify gravitation with electromagnetism. Unlike any other schemes, apparent net electric charges arise naturally because the direction of the electric field reverses along a time reversing path." "Deriving the U(1) bundle as a measure of the twisting of the time axis is new, as is the application to manifolds that are not time orientable. Like Kaluza Klein theory, it is purely classical, but free of the complications and ad hoc assumptions required by full 5D Kaluza Klein theories. It is remarkable how so much is derived from such a simple construction without additional assumptions." "The connection with quantum theory is intriguing. Classical structures that are not time orientable have close links with quantum phenomena such as the logical structure [4], particle creation and annihilation [14] and spin half [7] The derivation of Maxwell’s equations and electric charge is just another result from the same premise of non time orientability." Electric charges are a natural feature of the model, but quantisation only appears naturally for magnetic monopoles (which arise in pairs). However, adding elements of quantum theory to the monopole structures leads to quantisation of electric charge. The simplest such argument uses quantisation of angular momentum, but the argument fails when more than one monopole is introduced. The other approach uses a wavefunction for a charged particle [1, p262]. Uniqueness of the phase of the wavefunction leads to quantisation of charge. This is a tantalising link between the complex phase of the wavefunction and the orientability of spacetime." [0] https://warwick.ac.uk/fac/sci/physics/staff/academic/mhadley/ https://warwick.ac.uk/fac/sci/physics/staff/academic/mhadley... [1] https://doi.org/10.1007/s10773-017-3344-4 https://doi.org/10.1007/s10773-017-3344-4

T-A 6y ago
In your quote of the abstract, you conveniently left out the last sentence: "The treatment is purely classical, but motivated by links between acausal structures and quantum theory." This is not unification of QM and GR, it's a classical construction which the author speculates might lead to such a thing. Such things have been around for a long time; the obvious (and far more progressed) example is string theory.
- cinquemb 6y ago
  What you quote doesn't deny "no compatability" of the author… (I didnt say it was THE unification theory of QM and GR, you somehow inferred that, why? i dont know) and irrelevant when the author points out where the overlaps lie (what I quoted last). I could add that quote and it would change nothing as far as I'm concerned what the authors stance is on "no compatability". Hell, even in the second quote even mentions "it is purely classical" in reference to the derivation… The author also doesn't also think very highly of string theory: https://warwick.ac.uk/fac/sci/physics/staff/academic/mhadley/heretical/ https://warwick.ac.uk/fac/sci/physics/staff/academic/mhadley... Whether something is "more progressed" hardly matters in matters that still have many questions and more reflective of a consensus of the time that progresses one funeral at a time.
  - T-A 6y ago
    > What you quote doesn't deny "no compatability" of the author What I quote shows that the author knows and acknowledges that he's describing a classical construct. The question of "compatability" (sic) is not even addressed. > I didnt say it was THE unification theory of QM and GR, you somehow inferred that I did not. Here's what I wrote: "This is not unification of QM and GR, it's a classical construction". Not the absence of any "THE", whether capitalized or not. > I could add that quote and it would change nothing as far as I'm concerned what the authors stance is Because you do not understand what the author is saying. He's presenting a purely classical model which displays some features (in particular charge quantization) also seen in quantum mechanical ones. That does not make it a quantum theory, any more than the discrete eigenfrequencies of a vibrating classical string make a classical model of vibrating strings a quantum theory.

T-A 6y ago

In your quote of the abstract, you conveniently left out the last sentence: "The treatment is purely classical, but motivated by links between acausal structures and quantum theory." This is not unification of QM and GR, it's a classical construction which the author speculates might lead to such a thing. Such things have been around for a long time; the obvious (and far more progressed) example is string theory.

cinquemb 6y ago
What you quote doesn't deny "no compatability" of the author… (I didnt say it was THE unification theory of QM and GR, you somehow inferred that, why? i dont know) and irrelevant when the author points out where the overlaps lie (what I quoted last). I could add that quote and it would change nothing as far as I'm concerned what the authors stance is on "no compatability". Hell, even in the second quote even mentions "it is purely classical" in reference to the derivation… The author also doesn't also think very highly of string theory: https://warwick.ac.uk/fac/sci/physics/staff/academic/mhadley/heretical/ https://warwick.ac.uk/fac/sci/physics/staff/academic/mhadley... Whether something is "more progressed" hardly matters in matters that still have many questions and more reflective of a consensus of the time that progresses one funeral at a time.
- T-A 6y ago
  > What you quote doesn't deny "no compatability" of the author What I quote shows that the author knows and acknowledges that he's describing a classical construct. The question of "compatability" (sic) is not even addressed. > I didnt say it was THE unification theory of QM and GR, you somehow inferred that I did not. Here's what I wrote: "This is not unification of QM and GR, it's a classical construction". Not the absence of any "THE", whether capitalized or not. > I could add that quote and it would change nothing as far as I'm concerned what the authors stance is Because you do not understand what the author is saying. He's presenting a purely classical model which displays some features (in particular charge quantization) also seen in quantum mechanical ones. That does not make it a quantum theory, any more than the discrete eigenfrequencies of a vibrating classical string make a classical model of vibrating strings a quantum theory.