# Weekly Papers on Quantum Foundations (14)

Mechanical Jurisprudence and Domain Distortion: How Predictive Algorithms Warp the Law

Pruss, Dasha (2021) Mechanical Jurisprudence and Domain Distortion: How Predictive Algorithms Warp the Law. [Preprint]

Approaching probabilistic and deterministic nomic truths in an inductive probabilistic way

Kuipers, Theo A.F. (2021) Approaching probabilistic and deterministic nomic truths in an inductive probabilistic way. [Preprint]

The Philosophy of the Future of Science

Virmajoki, Veli (2021) The Philosophy of the Future of Science. [Preprint]

What Theoretical Equivalence Could Not Be

Teitel, Trevor (2021) What Theoretical Equivalence Could Not Be. [Preprint]

Physics and Metaphysics of Wigner’s Friends: Even Performed Premeasurements Have No Results

Author(s): Marek Żukowski and Marcin Markiewicz

“The unambiguous account of proper quantum phenomena must, in principle, include a description of all relevant features of experimental arrangement” (Bohr). The measurement process is composed of premeasurement (quantum correlation of the system with the pointer variable) and an irreversible decoher…

[Phys. Rev. Lett. 126, 130402] Published Fri Apr 02, 2021

What Is the Generalized Representation of Dirac Equation in Two Dimensions?. (arXiv:2104.00388v1 [quant-ph])

In this work, the general form of $2\times2$ Dirac matrices for 2+1 dimension is found. In order to find this general representation, all relations among the elements of the matrices and matrices themselves are found,and the generalized Lorentz transform matrix is also found under the effect of the general representation of Dirac matrices. As we know, the well known equation of Dirac, $\left( i\gamma^{\mu}\partial_{\mu}-m\right) \Psi=0$, is consist of matrices of even dimension known as the general representation of Dirac matrices or Dirac matrices. Our motivation for this study was lack of the general representation of these matrices despite the fact that more than nine decades have been passed since the discovery of this well known equation. Everyone has used a specific representation of this equation according to their need; such as the standard representation known as Dirac-Pauli Representation, Weyl Representation or Majorana representation. In this work, the general form which these matrices can have is found once for all.

Why is AI hard and Physics simple?. (arXiv:2104.00008v1 [cs.LG])

Authors: Daniel A. Roberts

We discuss why AI is hard and why physics is simple. We discuss how physical intuition and the approach of theoretical physics can be brought to bear on the field of artificial intelligence and specifically machine learning. We suggest that the underlying project of machine learning and the underlying project of physics are strongly coupled through the principle of sparsity, and we call upon theoretical physicists to work on AI as physicists. As a first step in that direction, we discuss an upcoming book on the principles of deep learning theory that attempts to realize this approach.

Time Symmetry in Operational Theories. (arXiv:2104.00071v1 [quant-ph])

Authors: Lucien Hardy

The standard operational probabilistic framework (within which we can formulate Operational Quantum Theory) is time asymmetric. This is clear because the conditions on allowed operations are time asymmetric. It is odd, though, because Schoedinger’s equation is time symmetric and probability theory does not care about time direction. In this work we provide a time symmetric framework for operational theories in general and for Quantum Theory in particular.

The clearest expression of the time asymmetry of standard Operational Quantum Theory is that the deterministic effect is unique – meaning there is only one way to ignore the future – while deterministic (i.e normalised) states are not unique. In this paper, this time asymmetry is traced back to a time asymmetric understanding of the most basic elements of an operational theory – namely the operations (or boxes) out of which circuits are built. We modify this allowing operations to have classical incomes as well as classical outcomes on these operations. We establish a time symmetric operational framework for circuits built out of operations. In particular, we demand that the probability associated with a circuit is the same whether we calculate it forwards in time or backwards in time. We do this by imposing various double properties. These are properties wherein a forward in time and a backward in time version of the same property are required. In this paper we provide a new causality condition which we call double causality.

The topological order of the space. (arXiv:2104.00227v1 [gr-qc])

Authors: Jingbo Wang

Topological order is a new type order that beyond Landau’s symmetry breaking theory. The topological entanglement entropy provides a universal quantum number to characterize the topological order in a system. The topological entanglement entropy of the BTZ black hole was calculated and found that it coincides with that for fractional quantum Hall state. So the BTZ black holes have the same topological order with the fractional quantum Hall state. We conjecture that black holes in higher dimensions also have topological orders. Next we want to study the topological order of ordinary spaces which can be described by spin network states in loop quantum gravity. We advise to bring in the methods and results in string-net condensation to loop quantum gravity to solve some difficult problems.

A peek outside our Universe. (arXiv:2104.00521v1 [gr-qc])

Authors: Enrique GaztanagaPablo Fosalba

According to General Relativity (GR) a universe with a cosmological constant, Lambda, like ours, is trapped inside an event horizon r< sqrt(3/Lambda). What is outside? We show, using Israel (1967) junction conditions, that there could be a different universe outside. Our Universe looks like a Black Hole for an outside observer. Outgoing radial null geodesics can not escape our universe, but incoming photons can enter and leave an imprint on our CMB sky. We present a picture of such a fossil record from the analysis of CMB maps that agrees with the Black Hole universe predictions but challenge our understanding of the origin of the primordial universe.

Quantum Measurement of Space-Time Events. (arXiv:2011.11541v3 [quant-ph] UPDATED)

Authors: Dorje C. BrodyLane P. Hughston

The phase space of a relativistic system can be identified with the future tube of complexified Minkowski space. As well as a complex structure and a symplectic structure, the future tube, seen as an eight-dimensional real manifold, is endowed with a natural positive-definite Riemannian metric that accommodates the underlying geometry of the indefinite Minkowski space metric, together with its symmetry group. A unitary representation of the 15-parameter group of conformal transformations can then be constructed that acts upon the Hilbert space of square-integrable holomorphic functions on the future tube. These structures are enough to allow one to put forward a quantum theory of phase-space events. In particular, a theory of quantum measurement can be formulated in a relativistic setting, based on the use of positive operator valued measures, for the detection of phase-space events, hence allowing one to assign probabilities to the outcomes of joint space-time and four-momentum measurements in a manifestly covariant framework. This leads to a localization theorem for phase-space events in relativistic quantum theory, determined by the associated Compton wavelength.

Maxwellian mirages in general relativity. (arXiv:2012.08077v2 [gr-qc] UPDATED)

Authors: L.L. WilliamsN. Inan

Maxwellian approximations to linear general relativity are revisited in light of relatively recent results on the degrees of freedom in the linear gravitational field. The well-known Maxwellian formalism obtained in harmonic coordinates is compared with a Maxwellian formalism obtained under a coordinate choice where each of the metric components corresponds to each of the coordinate-invariant degrees of freedom of the linear gravitational field. The coordinate freedom of general relativity can be exploited to cast the field equations into Maxwellian form, but such forms can be mere mirages of the coordinate choice — mirages such as vector gravitational waves. A coordinate choice that yields perfectly-Maxwellian field equations, will yield a force equation that is not Lorentzian. If field definitions are chosen to obtain Lorentz-like terms in the force equation, then Maxwellian forms are compromised in the field equations. Many treatments of gravito-electromagnetism will make inconsistent ordering choices between the field equations and force equations, or else truncate terms of relevant order from the force equation. Often such mistakes reflect an attempt to force exact Maxwellian analogs simultaneously in both the field equations and the force equation, with the result that terms dropped are as large as those kept.

Knock-out interpretability

Nature Physics, Published online: 02 April 2021; doi:10.1038/s41567-021-01224-0

A detailed analysis of a nucleon-knockout experiment has put forward a methodological roadmap for overcoming ambiguities in the interpretation of the data — promising access to the nuclear wave functions in unstable nuclei.

Unreal art and hidden physics

Nature Physics, Published online: 01 April 2021; doi:10.1038/s41567-021-01220-4

Unreal art and hidden physics

Mind-body interaction and modern physics

Anastopoulos, Charis (2020) Mind-body interaction and modern physics. [Preprint]

Noether’s Theorems and Energy in General Relativity

De Haro, Sebastian (2021) Noether’s Theorems and Energy in General Relativity. [Preprint]

QBism and the Limits of Scientific Realism

Glick, David (2021) QBism and the Limits of Scientific Realism. [Preprint]

Representation in Measurement

Vessonen, Elina (2021) Representation in Measurement. [Preprint]

Were EPR correct after all; did Bell miss a point

Thompson, John F (2021) Were EPR correct after all; did Bell miss a point. UNSPECIFIED.