My Science & Epistemology Researches
Tag indicating that the post contains a document of my work and that it is listed on the Portfolio page.
In stellar astrophysics, opacity ( k ) is a measure of a material’s resistance to the flow of radiative energy. One analytical descriptions of this phenomenon is Kramers’ opacity law, a power-law relation derived from atomic physics that characterizes how stellar matter interacts with radiation under specific thermodynamic conditions.
Brussi 2026_Brief on Kramers’ Opacity Law in Stellar Astrophysics
Brief analysis of Chandrasekhar’s formula on dynamic friction in the general case of galactic encounters in the study of Galactic Dynamics.
Spoiler: we get a result for the dynamical friction timescale which means that in a time span of a few Gyr, for instance with the values of our assumptions applied to the Milky Way, the orbit of a massive satellite has substantially reduced, while the orbit of lower mass satellites (such as globular clusters) has not been significantly affected by dynamic friction.
Brussi 2026_Chandrasekhar dynamical friction formula
The first to observe that the propagation of light was not instantaneous was the astronomer Giovanni Domenico Cassini (1625-1712); the first to estimate its speed, in 1676, was the Danish astronomer Ole Christensen Rømer (1644-1710), both based their observations on the solar system.
Brussi 2026_Ole Rømer and the finite speed of light
Some personal notes on the strange relativistic rotation effect, the Penrose-Terrell rotation, of a body moving at high speed; written in italian.
Brussi 2026_The Penrose-Terrell rotation
Some personal notes on the famous relativistic garage paradox, written in italian.
Brussi 2026_The Garage Paradox
At school, 50 years ago, they taught me a proof of the Pythagorean theorem.
I didn’t remember it and tried to make my own.
Among the dozen I’ve made, I’ll list a couple of demonstration drafts.
Brussi 2026_Pythagorean theorem 2
Brussi 2026_Pythagorean theorem 9
A brief note on the dispersion of low-redshift measurements in the Pantheon+ database. This is part of my study of the alternative interpretation of redshift that does not involve the expansion of the universe.
The Pantheon+ database is one of the largest and most precise cosmological data collections in the world, consisting of 1,701 light curves from 1,550 Type Ia supernovae (SnIa).
Brussi 2026_Pantheon+ low z issue
My thesis work (written in italian) is published in the University of Padova archive:
Brussi 2025_Epistemology of time and cosmological interpretations
As an appendix to the same thesis I put a first development draft of the non-standard framework, which, after significant revisions, later became my work
The URD Framework.
Abstract
The aims of this study on time are first to explore its ontological meaning in the historical developments that have accompanied its interpretative evolution, and then to examine some theoretical critical issues raised by recent literature. With some original theses, some alternative explanations for the expansion of the universe are then analyzed, which the current interpretation claims to be observed experimentally, by means of a model based on the ‘specific time’ of photons as an alternative to the ‘universal time’. Furthermore, it is hypothesized a model that considers the presence of an energy density in the cosmic fluid (called aether) that interacts with the incident radiation, thus determining a redshift effect in the wavelength, or an even longer time for the same radiation to diffuse. The consistency of ‘specific time’ has been verified with Minkowski spacetime, with Einstein’s principles of special relativity, and with Friedman’s equations of cosmic dynamics. Having demonstrated the fallacy of this ‘specific time’ hypothesis, the positive conclusion is that there is no need to postulate a universal time. Once one is defined, its uniqueness or universality can be demonstrated (within the limits of the adopted models). To complement the study, possible causes of the redshift, alternative to the standard cosmological model, were analyzed. It has been taken in consideration the hypothesis that the same universe behaves like a black body, emitting a radiation (the cosmic microwave radiation) that can interact with the observed photons coming from remote sources, attenuating their energy and determining their redshift. A cross section for photons, and a model for photon-photon interactions that respects the law of conservation of energy have therefore been hypothesized. As a basis for the conjectures, direct observational evidence was considered, not interpreted by means of theories, obtaining (from the comparison with other standard candles) better distance estimates than the official ones based on Hubble’s law. This addendum is included as an Annex, believing that the same conjectures and some original models can represent a reference for future in-depth studies.
The work is written in Italian (1.8 MB):
Brussi 2025_Epistemologia del tempo e interpretazioni cosmologiche
My opinion on anthropic prejudices.
A personal perspective, not just an epistemological one.
It’s a work developed to complement another on the epistemology of time, and it’s written in italian.
Brussi 2025_Sui pregiudizi antropici
A personal perspective, not just an epistemological one.
It’s a work developed to complement another on the epistemology of time, and it’s written in italian.
