Tag: Time

Tag that highlights when time is the characteristic topic of the post.

Galactic Energy Profiles I

Galactic Energy Profiles: GEP I. Radiant and Relativistic Fluxes

Update: I decided to publish this work, part of the GEP series, on Zenodo without peer review and to use it as a basic tool for building a subsequent dataset (GEP III). Note: This work is version 2.0 of the previous NAGE I work, which has been superseded.

Abstract
Standard galactic energy inventories typically focus on the virialized components of the system, namely the kinetic and gravitational potential energy, derived from baryonic mass distributions and stellar luminosity. This paper, the first in the Galactic Energy Profiles series, introduces a reproducible geometric framework for accounting radiant and relativistic fluxes as a standing energy reservoir. By considering the photon and neutrino escape time τ across the galactic Halo, we quantify the energy density of radiation currently in transit as a component of the total galactic budget, complementary to the standard flux-based description. The resulting closed-form expressions, together with the accompanying open-source Python implementation, are intended as a calibrated methodological baseline for the subsequent application of this framework to observed galactic samples.

Keywords
galactic energy inventory; energy residence time; galactic radiant fluxes; galactic Halo energy; galaxy morphology

Here is the Zenodo version of the paper (1.1 MB):

pdf Brussi 2026 GEP I

GEP I mean escape trajectory length

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References for laymen: What is energy?

The great physicist Richard Feynman (1918-1988) honestly admitted that in modern physics we have no idea what energy ‘per se’ is. He described it as a kind of magical accounting: in the universe (or rather, in an isolated system), a lot of things happen, but at the end of each day, if we add up certain numbers characteristic of each event, the total is always the same. That number that never changes is energy. It is never created or destroyed, but always transformed.

The scholastic answer, “Energy is the capacity to do work” (given as known the concepts of work, force, etc.), is actually incorrect, because energy naturally tends to ‘spread’; that is, it prefers disorder. And as described by Ludwig Boltzmann (1844-1906), the measure of this disorder, called entropy, always increases in an isolated system. But since entropy also defines energy’s ability to do work, this ability actually always decreases, whereas energy is always conserved.

A more technical way to think about energy comes from Emmy Noether (1882-1935), who demonstrated that every conservation law in physics derives from a symmetry: energy is conserved because the Universe has a “translational time symmetry,” meaning the laws of physics remain the same as time passes, and the quantity that mathematically must remain constant is energy. In these terms, one could say that energy is time.

One way to calculate energy is the one defined by Einstein (see Einstein’s formula for energy), even if we don’t know what ‘stuff’ it’s made of. Simply put: even if an object is still and tiny, it hides a monstrous amount of energy within itself thanks to its mass (the constant of proportionality c² is a really huge number). And if it then begins to move due to external action, this energy increases.

Conclusion
We could define energy as the invisible ‘engine’ of reality. We can’t ‘touch’ it, but it ensures that the universe keeps its accounts in order (including the symmetry of time). Every time we do something, or even simply exist, we participate in this immense exchange of ‘tokens’ that has been going on ‘forever’.

Richard Feynman e Emmy Noether

Richard FeynmanEmmy Noether

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Ontology vs. Epistemology of Time

My belief is that time does not exist in Nature.

To understand how time can be nonexistent in Nature while general relativity (GR) remains valid, it is necessary to distinguish between what the world is and how we describe it:
– Ontological Plane (Nature): Reality is an accident of events according to a ‘grammar’ of cause and effect. In this view, time does not exist as an external container or clock; there is only the logical necessity that certain events presuppose the occurrence of others. Nature does not ‘wait’ for time to pass: it acts according to an intrinsic causal ladder.
– Epistemological Plane (GR): General Relativity is our logical ‘map’. Since the human mind cannot perceive the entire network of atomic and discrete events, it uses the construct of spacetime to organize, measure, and, above all, predict.

Causality as the Skeleton of GR
In physics, the causal structure of a manifold is defined by the set of precedence relations between events. If Nature operates according to a ‘causal ladder’ (A must precede B), GR encodes this necessity through the metric tensor*.
The fact that GR ‘works’ means that its mathematical architecture faithfully respects the logical sequence of natural events. The coordinated time t of GR is nothing more than a numerical index that we assign to events to keep track of their causal succession.

Predictability vs. Occurrence
The difference between the anthropic and natural visions lies in the concept of determinism vs. necessity:
– For Nature: Things happen when they are meant to happen. There is no delay or waiting; there is only the satisfaction of causal conditions.
– For Human Beings (GR): We need predictability. For us, it is not enough to know that B will follow A; We want to know when (according to our parameters) and where. GR introduces tools like Cauchy hypersurfaces to allow us to calculate the ‘future’. This computational capacity is a human need: Nature does not calculate its next state, it simply executes it.

GR as a relational model
GR remains valid because it describes how matter-energy influences the configuration of causal links. Even if we eliminate the idea of ​​a ‘container’ time, GR continues to tell us how the logical proximity between events is altered by the presence of mass. In this sense, the curvature of spacetime is not the deformation of a ‘time substance’, but the deformation of the network of causal relations that constitutes the world.

In short: Nature is the ‘ladder’ of facts, GR is the technical manual that humanity has written to index that ladder and transform it into prediction.

Universe line (credits: wikipedia)


universe line

* The Metric Tensor (gμν)
Mathematically, a tensor can be understood here as a matrix that establishes how coordinates—representing spacetime events—transform from one reference frame to another while preserving physical invariants. The metric tensor specifically dictates the geometry of this manifold. In every point of the universe, it acts as a local ‘ruler’ and ‘chronometer’ by defining the spacetime interval (ds2 = gμνdxμdxν). Most crucially for causality, it shapes and tilts the light cones, which delineate the absolute geometric boundaries beyond which information cannot travel. Therefore, the metric tensor is the mathematical structure that translates the causal sequence (event A preceding event B) into the invariant fabric of spacetime geometry.

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Leonard Susskind about the c constant

An in-depth analysis by Leonard Susskind of the constant c, commonly referred to as the “speed of light.” It is essentially a collection of familiar concepts, but reinterpreted in an illuminating way, that are well worth considering.

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Cosmology for a static universe

Abstract

This brief work, then became an Appendix to my URD Framework study, proposes a cosmological model characterized by a globally flat, spatially infinite, and non-time-limited spacetime. It challenges the standard application of the Friedmann-Lemaître-Robertson-Walker metric by reinterpreting general relativity as a strictly local phenomenon within a non-continuum matter distribution. In this framework, the observed flatness of the universe is a fundamental geometric property rather than a dynamical result of inflation, and cosmological redshift is modeled as a cumulative energy dissipation process rather than metric expansion.

pdf  Brussi 2026_Cosmology for a static universe

gravitational emotion

Ai generated image from free Adobe stock

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My thesis work

My thesis work (written in italian) is published in the University of Padova archive:
pdf_ita  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
link  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):

pdf_ita  Brussi 2025_Epistemologia del tempo e interpretazioni cosmologiche

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Overview of time at the beginning of modern science

A short essay on Time at the beginning of modern science.
A personal perspective, not just an epistemological one.
It’s part of a work developed on the epistemology of time, and it’s written in italian.

pdf_ita  Brussi 2024_Panoramica sul tempo agli inizi della scienza moderna

 

Brussi 2024_Panoramica sul tempo agli inizi della scienza moderna

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Gödel’s conjecture on the unreality of time

A brief look at the conjecture on the unreality of time of Kurt Gödel (1906-1978).
It’s a work developed to complement another on the epistemology of time, and it’s written in italian.

pdf_ita  Brussi 2023_Congettura di Gödel sull’irrealtà del tempo

 

Brussi 2023_Congettura di Gödel sull’irrealtà del tempo

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