Recent content by A. Neumaier

Try my book on algebraic quantum physics, it might convince you of the opposite!

Indeed, relativistic multiparticle quantum mechanics is consistent (and useful) but has, compared to relativistic quantum field theory, a much more limited domain of applicability. A good survey article is B.D. Keister and W.N. Polyzou, Relativistic Hamiltonian dynamics in nuclear and particle...

In differential geometry, there is a covariant concept of a 4-vector, and the momentum vector is such a 4-vector. Only the coordinates of this 4-vector depend on the frame. Thus the momentum is an intrinsic property of a particle, which can be used to differentiate between two of them, while...

1. Local and global symmetries are essentially different concepts. Electromagnetism has a local U(1) gauge symmetry that is essential to understand the properties of the e/m field. The other gauge theories are generalization that were found to work well. This is the real justification for their...

Any relativistic quantum field theory needs an underlying globally hyperbolic manifold.

I am beyond this stage and therefore have more freedom!

This is a bug in the rendering by the preprint server. Look at https://arnold-neumaier.at/ms/Laplace.pdf for my own, good version.

The (strongly modified) submitted version is here. A poster for a conference next week in Vienna summarizes everything on one page.

So it is extra structure assumed, beyond the textbook requirenments for a quantum system. Not a good sign for an interpretation of quantum mechanics.

The statement is basis-independent. For example, any ##\rho=\pi\psi^*## with normalized ##\psi## is a rank 1 projector. Given a Hilbert space and a Hamiltonian (and hence a physical system), what is a definite configuration?

One can prove that every finite- rank density matrix can be written as a convex combination of projectors, and that every density matrix can be written as the limit of a family of convex combinations of projectors.

Of course they are well-defined. In a long distance Bell experiment, Alice sees the effects of one of the entangled photons, not even knowing whether there is an entangled partner somewhere. For her, the only system is the subsystem, and it has all the properties a single photon has. This is...

But they amount to unverifiable speculation.

Bohmian mechanics is a different interpretation, limited to nonrelativistic quantum mechanics. Thus this incompatibilty is a plus for the new approach! Yes. This is discussed In Section 13 of my paper.

But only the quasiclassical ones are checkable by us, and hence only these convey an objective physical meaning in the sense used by the physics community.