A Universal quantum physics

[A. Neumaier]

TL;DR

a quantum version of Laplace's classical, mechanical universe

Based on the thermal interpretation, I developed a quantum version of the classical, mechanical universe suggested by Laplace over 200 years ago.

Abstract. The purpose of this paper is to propose a quantum version of the classical, mechanical universe suggested by Laplace over 200 years ago. The proposed theory operates fully within the established mathematical formalism of quantum field theory.
The proposed theory unifies the classical and quantum intuition about the macroscopic and microscopic, deterministic and stochastic, local and nonlocal aspects of our world. It entails the best features of several traditional strands of fundamental research, but avoids many of their drawbacks and limitations.

The proposed theory shares
(i) with quantum field theory the local dynamics of quantum fields;
(ii) with statistical mechanics the reduced density operator and coarse graining techniques, but gives them a deterministic meaning for single quantum systems;
(iii) with the statistical interpretation the effective stochastic quantum properties, but explains its deterministic origin;
(iv) with quantum information theory the maximum entropy principle, but gives it an objective meaning;
(v) with the Copenhagen interpretation the importance of classical aspects in quantum experiments, but realized in a pure quantum context;
(vi) with quantum chemistry nonlinear models for mixed quantum-classical dynamics;
(vii) with quantum cosmology the assumption of a universal quantum state, but not assumed to be pure;
(viii) with the thermal interpretation the focus on quantum values for the description of measurements, rather than on eigenvalues;
(ix) with hidden variable theories a nonlocal deterministic dynamics of quantum values, but given by the familiar N-point functions; and
(x) with the many worlds interpretation the unitary dynamics of the universe, but realized in a single world.

In particular, the proposed theory is made compatible with scientific realism by a simple but powerful reinterpretation of some of the formal terms in quantum field theory as in the thermal interpretation. As a result, there is a coherent story to be told about how quantum physics works.

 

[renormalize]

TL;DR: a quantum version of Laplace's classical, mechanical universe

Is your paper submitted for, or in the process of, publication?

 

[A. Neumaier]

Is your paper submitted for, or in the process of, publication?

It is finished for submission, and I put it online to get some early feedback before actually submitting it (in a few weeks). So the submitted version will perhaps be a little different.

 

[Morbert]

From the paper:

Universal quantum physics is fully compatible with scientific realism ([92]; cf. Fraser [42]) in the sense that one may take every feature expressible in terms of N -point functions for N = 0, 1, 2, . . . as being real and objective, independent of human perception.

I suspect this is the part of the paper that will be most alien to readers (apart from the algebraic QFT which will be esoteric to readers in general). But I think this is not surprising as this thermal interpretation aspect is also the most novel aspect of the paper.

 

[Ben vdP]

The article is interesting, but a lot to absorb. Just a few minor points:

-
You could say a quantum particle has a wave aspect and a particle aspect.
In above sentence "particle" has two different meanings.

In the article the term "particle" is also used for both.
Sometimes for the quantum field; sometimes for the classical everyday particle as in section 8.
I have no good suggestion here, but it is a bit confusing.

-
page 6

6C. The universal dynamics has no collapse. State reduction (or collapse) of the state of a
physical system is a time-resolved, continuous process.

Would this be equivalent to say that in an experiment when making a measurement with a device (e.g. double slit) then
there is an interaction that impacts the quantum particle causing it to change state?
Do you provide a mechanism within this formalism?


page 8 bottom

basis of this beleiv. -> believe.

page 27

very close to a perticle -> particle or quantum particle

 

[A. Neumaier]

In the article the term "particle" is also used for both.
Sometimes for the quantum field; sometimes for the classical everyday particle as in section 8.
I have no good suggestion here, but it is a bit confusing.

A (classical or quantum) particle is a quantum field concentrated at each time in a small region of space.
I tried to avoid the use of ''particle'' in any other way; if you see other uses, please let me know.

6C. The universal dynamics has no collapse. State reduction (or collapse) of the state of a
physical system is a time-resolved, continuous process.

Would this be equivalent to say that in an experiment when making a measurement with a device (e.g. double slit) then
there is an interaction that impacts the quantum particle causing it to change state?

Yes. Without interaction no measurement. And an interaction works in both directions, changing the state of all participants.

Do you provide a mechanism within this formalism?

This is the measurement problem, analyzed in Section 12. In a semiclassical approximation, this is well understood, see ref. [3], but in a full quantum treatment there are still open problems, discussed there.

page 8 bottom
page 27

Thanks for your close reading!

 

[A. Neumaier]

From the paper: I suspect this is the part of the paper that will be most alien to readers (apart from the algebraic QFT which will be esoteric to readers in general). But I think this is not surprising as this thermal interpretation aspect is also the most novel aspect of the paper.

I tried to define everything that is not in typical textbooks.

For a single field $\phi$, the N-point function is simply the map (and in fact for $N>1$ the distribution) defined by all quantum values
$$W(x_1\ldots,x_N):=\langle\phi(x_1)\cdots\phi(x_N)\rangle.$$