arXiv subjects

Theodorus Maria Nieuwenhuizen

Publications and source records attributed to Theodorus Maria Nieuwenhuizen.

10 recordsLinked to original sources

arXiv2026

Hopfield model for patterns with internal structure

The spherical version of the Hopfield model for pattern recognition is considered in the static limit. Structures inside the patterns are modeled by Gaussian random variables that reward correlation between pairs of spins in a given pattern. The free energy is derived analytically with the replica method. The overlap distribution obeys a self-consistent equation. Coming from high temperatures, a spin glass phase is entered, in which patterns and correlations appear at lower temperatures. For small enough loading capacity, also a glass phase with patterns and correlations appears.

cond-mat.dis-nn↗

arXiv2026

Dynamics of ideal quantum measurement of a spin 1 with a Curie-Weiss magnet

Quantum measurement is a dynamical process of an apparatus coupled to a test system. Ideal measurement of the $z$-component of a spin-$\frac{1}{2}$ ($s_z=\pm\frac{1}{2}$) has been modeled by the Curie-Weiss model for quantum measurement. Recently, the model was generalized to higher spin and the thermodynamics was solved. Here the dynamics is considered. To this end, the dynamics for spin-$\frac{1}{2}$ case are cast in general notation. The dynamics of the measurement of the $z$-component of a spin-1 ($s_z=0,\pm 1$) are solved in detail and evaluated numerically. Energy costs of the measurement, which are macroscopic, are evaluated. Generalization to higher spin is straightforward.

quant-ph↗

arXiv2024

Indefinitely flat rotation curves from Mpc sized charged cocoons

Weak lensing exhibits that rotation curves of isolated galaxies remain flat up to Mpc scale (Mistele et al, 2024). Recently we proposed that dark matter is a combination of electrostatic and vacuum energy in standard physics. In this theory, isolated galaxies may be embedded in ``charged cocoons'', spheres with $\pm 1/r^2$ charge density. The related circular rotation curves decay at the Mpc scale. The analytic solution is extended to the early Universe. A peak in the cosmic microwave background spectrum is expected at the arcsec scale. The induced nanometer size of the cocoons at the Big Bang makes the initial state inhomogeneous.

physics.gen-ph↗

arXiv2024

Solution of the dark matter riddle within standard model physics: From black holes, galaxies and clusters to cosmology

It is postulated that the energy density of the (quantum) vacuum acts firstly as dark energy and secondly as a part of dark matter. Assisted by electric fields arising from a small charge mismatch in the cosmic plasma, it can condense on mass concentrations. No longer participating in the cosmic expansion, this constitutes ``electro-aether-energy'' (EAE), ``electro-zero-point-energy'' or ``electro-vacuum-energy'', which solves the dark matter riddle without new physics. A radial electric field of 1 kV/m is predicted in the Galaxy. For proper electric fields, EAE can cover the results deduced with MOND. An instability allows a speedy filling of dark matter cores. Hydrostatic equilibrium in galaxy clusters is obeyed. Flowing in of EAE explains why black holes become supermassive, do not have mass gaps and overcome the final parsec problem. Rupture of charged clouds reduces, e. g., the primordial baryon cloud to the cosmic web. The large coherence scale of the electric field acts as a scaffold for gentle galaxy formation and their vast polar structures. In galaxy merging and bars, there occurs no dynamical friction. At cosmological scales, EAE acts as pressureless dark matter. Its amount increases in time, which likely solves the Hubble tension by its late time physics. A big crunch can occur. Of the large cosmological constant injected at the Big Bang, a small part kept that form, without fine-tuning.

physics.gen-ph↗

arXiv2024

The smeared-horizon observer of a black hole

A class of observers is introduced that interpolate smoothly between the Schwarzschild observer, stable at spatial infinity, and the Kerr-Schild observer, who falls into a black hole. For these observers the passing of the event and inner horizon takes a finite time, which diverges logarithmically when the interpolation parameter $σ$ goes to zero. In the field theoretic approach to gravitation, the behavior at the horizons becomes regular, making the mass of the metric well defined.

physics.gen-ph↗

arXiv2023

Contra multos verbos: On scandals of quantum mechanics

In 2008 Nico van Kampen wrote in his letter {\it The scandal of quantum mechanics}: ``The scandal is that there are still many articles, discussions and textbooks, which advertise various interpretations and philosophical profundities." Not much has changed since then, while social media have given a platform for more of what Nico would term ``a scandal''. A detailed viewpoint is presented on the status of quantum mechanics, distilled from two decades of work with Armen Allahverdyan and Roger Balian on the dynamical solution of Curie-Weiss models for quantum measurement. It embodies a certain minimal form of the statistical interpretation and stays clear of ontological connections. Along the way, comments on various related subjects, terms and interpretations are given.

quant-ph↗

arXiv2023

Models for quantum measurement of particles with higher spin

The Curie-Weiss model for quantum measurement describes the dynamical measurement of a spin-$\frac{1}{2}$ by an apparatus consisting of an Ising magnet of many spins $\frac{1}{2}$ coupled to a thermal phonon bath. To measure the $z$-component $s=-l,-l+1,\cdots,l$ of a spin $l$, a class of models is designed along the same lines, which involve $2l$ order parameters. As required for unbiased measurement, the Hamiltonian of the magnet, its entropy and the interaction Hamiltonian possess an invariance under the permutation $s\to s+1$ mod $2l+1$. The theory is worked out for the spin-1 case, where the thermodynamics is analyzed in detail, and for spins $\frac{3}{2},2,\frac{5}{2}$ the thermodynamics and the invariance is presented.

quant-ph↗

arXiv2023

Exact solutions for black holes with a smooth quantum core

A class of exact solutions are presented for the interior of black holes of solar mass and beyond. In a core enclosed by the inner horizon, the binding energy released by dissolution of the pre-collapse nuclei is stored in electrostatic and zero point energy. Gravitational collapse is prevented by their negative pressures. In the mantle, the region between the inner and event horizons, there is a standard vacuum. Accounting for the rest masses of the up and down quarks and electrons leads to corrections at the per cent level. Spherically symmetric fluctuations have a spectrum without unstable modes. A surface layer with a charge current can be present on the outer side of the inner horizon; a layer of opposite charges on the event horizon can make an extremely charged black hole neutral. Merging of an extremal black hole with another extremal one or with a neutron star may produce electromagnetic fireworks.

gr-qc↗

arXiv2017

Subjecting dark matter candidates to the cluster test

Galaxy clusters, employed by Zwicky to demonstrate the existence of dark matter, pose new stringent tests. If merging clusters demonstrate that dark matter is self-interacting with cross section $σ/m\sim 2$ cm$^2$/gr, MACHOs, primordial black holes and light axions that build MACHOs are ruled out as cluster dark matter. Recent strong lensing and X-ray gas data of the quite relaxed and quite spherical cluster A1835 allow to test the cases of dark matter with Maxwell-Boltzmann, Bose-Einstein and Fermi-Dirac distribution, next to Navarro-Frenck-White profiles. Fits to all these profiles are formally rejected at over $5σ$, except in the fermionic situation. The interpretation in terms of (nearly) Dirac neutrinos with mass of $1.61^{+0.19}_{-0.30}$ eV/$c^2$ is consistent with results on the cluster A1689, with the WMAP, Planck and DES dark matter fractions and with the nondetection of neutrinoless double $β$-decay. The case will be tested in the 2018 KATRIN experiment.

astro-ph.CO↗

arXiv2017

How Zwicky already ruled out modified gravity theories without dark matter

Various theories, such as MOND, MOG, Emergent Gravity and $f(R)$ theories avoid dark matter by assuming a change in General Relativity and/or in Newton's law. Galactic rotation curves are typically described well. Here the application to galaxy clusters is considered, focussed on the good lensing and X-ray data for A1689. As a start, the no-dark-matter case is confirmed to work badly: the need for dark matter starts near the cluster centre, where Newton's law is still supposed to be valid. This leads to the conundrum discovered by Zwicky, which is likely only solvable in his way, namely by assuming additional (dark) matter. Neutrinos with eV masses serve well without altering the successes in (dwarf) galaxies.

astro-ph.CO↗