arXiv subjects

Bruce Miller

Publications and source records attributed to Bruce Miller.

5 recordsLinked to original sources

arXiv2026

Scaling Accessible Mathematics on arXiv: HTML Conversion and MathML 4

We report on the ongoing development of arXiv's HTML Papers offering, available on every new TeX/LaTeX submission since its initial release in 2023. The main highlights from 2025 and early 2026 are: (i) community-driven improvements to HTML fidelity and service health, with roughly half of 6,000 user reports resolved; (ii) corpus-scale conversion work aimed at 90% error-free HTML (currently 75%); (iii) initial MathML 4 Intent annotations for accessible speech output; (iv) an in-progress Rust port of LaTeXML, reducing compute costs and enabling faster previews on submission. The arXiv HTML Papers project remains experimental, but is gradually maturing as we better understand the needs of arXiv's readers and the technical opportunities presented by new standards and by advances in programming languages and AI.

cs.CL↗

arXiv2026

The Bondi universe: Can negative mass drive the cosmological expansion?

We identify a new cosmological coincidence that parallels the well-known matter/dark-energy coincidence: the present-epoch transition of the universe from a weakly coupled (collisionless) to a strongly coupled (collisional) gravitational regime. Within a cosmological model containing equal amounts of positive and negative Bondi masses -- consistent with the weak equivalence principle and momentum conservation -- we show that this coupling transition naturally coincides with the shift from a coasting to an accelerating expansion. A linear response analysis of the corresponding Vlasov-Poisson system reveals that mixed positive-negative mass configurations are always unstable, with growth rates that increase at shorter wavelengths, thereby driving the system toward strong coupling. Using long-time, exact one-dimensional N-body simulations, we demonstrate that the universe undergoes three successive expansion phases: an initial ballistic regime, an intermediate random-walk acceleration driven by sporadic Bondi encounters, and finally a uniformly accelerating phase triggered by the formation of stable positive/negative mass pairs. The onset of this last phase occurs precisely when the coupling parameter crosses unity, linking the two cosmological coincidences through a single dynamical mechanism. These results suggest that cosmic acceleration may arise from the nonlinear dynamics of a gravitationally neutral mixed-mass universe, without invoking dark energy or a cosmological constant.

astro-ph.CO↗

arXiv2021

MOND-like behavior in the Dirac-Milne universe -- Flat rotation curves and mass/velocity relations in galaxies and clusters

We show that in the Dirac-Milne universe (a matter-antimatter symmetric universe where the two components repel each other), rotation curves are generically flat beyond the characteristic distance of about 3 virial radii, and that a Tully-Fisher relation with exponent $\approx 3$ is satisfied. Using 3D simulations with a modified version of the RAMSES code, we show that the Dirac-Milne cosmology presents a Faber-Jackson relation with a very small scatter and an exponent equal to $\approx 3$ between the mass and the velocity dispersion. We also show that the mass derived from the rotation curves assuming Newtonian gravity is systematically overestimated compared to the mass really present. We also show that the Dirac-Milne universe, featuring a polarization between its matter and antimatter components, presents a behavior similar to that of MOND (Modified Newtonian Dynamics), characterized by an additional surface gravity compared to the Newtonian case. We show that in the Dirac-Milne universe, at the present epoch, the intensity of the additional gravitational field $g_{am}$ due to the presence of clouds of antimatter is of the order of a few $10^{-11}$ m/s$^2$, similar to the characteristic acceleration of MOND. We study the evolution of this additional acceleration $g_{am}$ and show that it depends on the redshift, and is therefore not a fundamental constant. Combined with its known concordance properties on SNIa luminosity distance, age, nucleosynthesis and structure formation, the Dirac-Milne cosmology may then represent an interesting alternative to the $\Lambda$CDM, MOND, and other scenarios for explaining the Dark Matter and Dark Energy conundrum.

astro-ph.GA↗

arXiv2018

Cosmological structure formation with negative mass

We construct a family of models with negative gravitational mass in the context of Newtonian gravity. We focus in particular on a model that reproduces the features of the so-called Dirac-Milne universe, a matter-antimatter symmetric universe that was recently proposed as an alternative cosmological scenario [A. Benoit-Levy and G. Chardin, A&A 537, A78 (2012)]. We perform one-dimensional N-body simulations of these negative-mass models for an expanding universe and study the associated formation of gravitational structures. The similarities and differences with the standard cosmological model are highlighted and discussed.

gr-qc↗

arXiv2015

Cosmology in One Dimension: Vlasov Dynamics

Numerical simulations of self-gravitating systems are generally based on N-body codes, which solve the equations of motion of a large number of interacting particles. This approach suffers from poor statistical sampling in regions of low density. In contrast, Vlasov codes, by meshing the entire phase space, can reach higher accuracy irrespective of the density. Here, we performed one-dimensional Vlasov simulations of a long-standing cosmological problem, namely the fractal properties of an expanding Einstein-de Sitter universe in Newtonian gravity. The N-body results were confirmed for high-density regions and extended to regions of low matter density, where the N-body approach usually fails.

astro-ph.CO↗