Mastodawn

My #paperOfTheDay was "Galilei invariance, action-reaction principle, and center of mass theorem" from 1983.
This is an article about #generalRelativity , without anything quantum. From daily experience, we know that every object has a mass, but thinking more closely, the parameter we call mass actually appears in different ways in #physics, and it is not a priory clear how they are logically related. Einstein's famous thought experiment was about the "falling elevator", that is, if you are in a box and can't look outside, you can not distinguish whether you fall freely, or you are located far away from a planet where there is no gravitational field. This "weak equivalence principle" asserts the equivalence between "inertial mass", the parameter which determines how hard it is to accelerate something, and "passive gravitational mass", the parameter that determines how strongly a gravitational field acts on an object.
But there is a third type of mass, the "active gravitational mass", which determines how much gravitational field is generated by an object. The "strong equivalence principle" asserts that all three masses are the same.
The present article demonstrates that, as far as classical celestial mechanics is concerned, the strong equivalence principle can not been distinguished from the weak one. That is, the observed motion of celestial bodies can already be explained by the weak equivalence principle, regardless of whether the strong one holds or not.
I don't know what the current state of affairs is in that question, in particular regarding quantum theory.
https://link.springer.com/article/10.1007/BF01889417

Galilei invariance, action-reaction principle, and center of mass theorem - Foundations of Physics

The Galilei invariance of classical dynamics does not automatically imply the third Newtonian axiom and the center of mass theorem. For the deduction of these theorems from Galilei invariance we must have, generally, a “kinematical potential” (Helmholtz) and a “potential function” (Clausius), respectively. In celestial mechanics it is possible to have conservation of the motion of the center of gravity but not of the mass center. In this case, the active and the passive masses are different quantities.

SpringerLink

Scientific World Apr 18

Discover whether Einstein’s theory of relativity can fully explain black hole singularities, where gravity becomes infinite, or if quantum physics is needed to solve the mystery.
#EinsteinRelativity #BlackHoleSingularity #QuantumGravity #GeneralRelativity #UniverseSecrets
https://www.scientificworldinfo.com/2026/04/can-relativity-explain-black-hole-singularities.html

Can Einstein’s Relativity Explain the Behavior of Black Hole Singularities?

Einstein’s Theory of General Relativity predicts the existence of black hole singularities but cannot fully explain their behavior, as the e...

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BGDon 🇨🇦 🇺🇸 👨‍💻Apr 16

Well that takes a load of my mind - I'm glad we got to the bottom of this!

Researchers @ University of Pennsylvania have confirmed that gravity's strength weakens with distance almost exactly as predicted by the equations developed by Newton and later incorporated into Einstein's theory of general relativity. https://phys.org/news/2026-04-gravity-newton-einstein-cosmic-scales.html #Gravity #Newton #Einstein #GeneralRelativity #TheoreticalPhysics #Physics #Astrophysics #Universe #Galaxies #UniversityofPennsylvania

FundamentalTime Mar 26

New preprint submitted to Classical and Quantum Gravity:

GR is time-symmetric. That symmetry is the root of singularities, information loss, and the arrow of time.

We propose the opposite: irreversibility is fundamental.

Main result: gravitational collapse halts before any trapped surface forms. C_max < 1. No quantum gravity needed.

📎 https://doi.org/10.5281/zenodo.19240251

#GeneralRelativity #ArrowOfTime #TheoreticalPhysics

Entropic I‑Field Theory: Fundamental Irreversibility and the Resolution of Singularities, Information Loss, and the Arrow of Time

General relativity is time-symmetric. This symmetry is the root of its three deepest puzzles: singularities, information loss, and the arrow of time. All existing approaches treat irreversibility as emergent — a statistical mirage atop a reversible microreality. We propose the opposite. Irreversibility is fundamental. It is encoded in a classical scalar field $I$ — the I-field — that couples universally to gravity and matter. Its dynamics are governed by an Euler-Lagrange-Rayleigh action, where a dissipation term $\gamma u^\mu \nabla_\mu I$ breaks time-reversal symmetry at the level of the field equation. The modified Einstein equations introduce a dimensionless stabilization index $\eta$ that quantifies I-field backreaction. The consequences are direct: - Gravitational collapse halts at a finite critical density $\rho_c$, before a trapped surface can form. The maximal compactness satisfies $\mathcal{C}_{\max} < 1$. - No event horizon ever appears — information remains causally accessible throughout the evolution. - The arrow of time emerges from the field dynamics, not from boundary conditions or statistical postulates. Three foundational problems are thus resolved within a single classical framework, from first principles, without invoking quantum gravity.

Zenodo

Xavier Mareca Mar 24

The long‑term tracking of star S2 orbiting Sagittarius A* continues to be one of the most compelling confirmations of General Relativity. Over 27 years of observations show a clear Schwarzschild precession: the orbit doesn’t close but slowly rotates due to the intense curvature of spacetime near the supermassive black hole.
A beautiful example of how precision astronomy can test fundamental physics.

#Astrophysics #GeneralRelativity #BlackHoles #Science

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KilleansRow 🇺🇲 🇺🇦🍀Mar 18

2/n…somewhat inelastic view of #GeneralRelativity , along with preferred avoidance of #Engineering.
Those likely to be recruited into a reverse engineering program setting are tasked with giving data on craft and observables context. #GR gives you a set of bounds at the origin , a starting point. In one approach to fitting for the data and observables you need your vehicle to become effectively massless. If you find a path to that you’ve not “ broken relativity “. Gravity will still be there...

FundamentalTime Mar 17

I developed a new field theory of gravitational collapse — no singularities,
no event horizons, information preserved by construction.

Submitted to EPJC: desk rejected, not read.
Submitted to GRG: rejected after review, zero reviewer comments.

I am an independent researcher. The mathematics does not change
depending on who signs the cover letter.
The paper is publicly available: https://doi.org/10.5281/zenodo.18818991
Genuine criticism welcome.
#physics #generalrelativity #openscience #independentresearch

The I-Field Theory: Fundamental Irreversibility and Gravitational Collapse Without Horizons

We introduce the Entropic I-Field Theory, establishing fundamental irreversibility as a new physical principle through an Euler-Lagrange-Rayleigh action formalism. The framework extends Einstein's equations by coupling to a universal scalar field—the I-field—whose dynamics break time-reversal symmetry via an explicit dissipation term $\gamma u^\mu \nabla_\mu I$. The field couples to matter through $\mathcal{J} = \rho/m_I$, where $\rho$ is the energy density and $m_I$ the I-field mass scale, ensuring dimensional consistency. We define the dimensionless **Stabilization Index** $\eta = (g_I^2 m_I/\gamma) \cdot [\lambda I^2/(\lambda I^2 + m_I^2)]$, which quantifies I-field backreaction strength and exhibits natural saturation behavior. Through rigorous analysis of the modified Friedmann equations, we prove that the I-field generates negative pressure $p_I \propto -\rho^2$ at high densities. This pressure opposes gravitational attraction, causing collapse to halt at a critical density $\rho_c$ where the acceleration reverses. The system reaches a finite minimal radius and subsequently re-expands, with maximal compactness $C_{\text{max}} < 1$ that precludes trapped surface formation. The framework provides unified conceptual resolution of three foundational problems: (1) **Singularity avoidance**—gravitational collapse stabilizes at finite radius without horizons or curvature singularities; (2) **Information preservation**—the absence of event horizons ensures all information remains causally accessible; (3) **Arrow of time**—temporal asymmetry emerges from fundamental field dynamics encoded in the dissipation term, rather than from statistical postulates or boundary conditions. The theory satisfies the correspondence principle, smoothly recovering general relativity in the limit $\gamma \to 0$ while preserving all established tests. This work establishes irreversibility as a fundamental rather than emergent feature of gravitational dynamics, extending physics from the time-symmetric framework of "Being" to the irreversible dynamics of "Becoming.

Zenodo

Ars Technica News Mar 13

Magnetars drag spacetime to power superluminous supernovae https://arstechni.ca/Q8qw #generalrelativity #astrophysics #supernova #magnetar #Science #Physics

Magnetars drag spacetime to power superluminous supernovae

Frame-dragging may explain an odd pattern seen in the brightest supernovae.

Ars Technica

KilleansRow 🇺🇲 🇺🇦🍀Mar 6

1/n Notes on #UAP Discussions : This particular exploration is a milestone. If we map what they eventually wind up talking about to vexing questions in current #Physics we have a direct confrontation with #GeneralRelativity, #QuantumMechanics, and the applied mass- energy firewall problem that lies at at the heart of several open problems in #Cosmology and the SM. It should be noted that the intuition of #Engineers in this case is capable of beating #Physicists to the punch.
There is a bit…

C.Mar 1

This is way above my pay grade, and I've only read the article, not the actual technical work underneath it (because my maths is insufficient to know what it's talking about, so there's not a lot of point). But it sounds really interesting.

https://muellerberndt.medium.com/how-observer-path-holography-improves-on-the-standard-model-and-general-relativity-c971c376027e

I've never heard of "observer patch holography" (note typo in slug text), but a theoretical framework which has just a single free variable but lets you derive general relativity and the standard model, correctly predicting a bunch of magic numbers that we input as free variables into the standard model, is interesting as hell.

Maybe someone smarter than me has already looked at this and debunked it. Sabine doesn't seem to have done a video on it (or I missed it). And "one guy with four information theory axioms solves all of physics' problems" is definitely on the Hollywood-script end of the plausibility scale, but who knows? Weirder things have happened.

@cenobyte - thought of you, of course.

#StandardModel #physics #GeneralRelativity #GR #ObserverPatchHolography #OPH #quantum

How Observer Patch Holography Improves on the Standard Model and General Relativity

The Standard Model can’t predict a single particle mass. General Relativity needs invisible matter to work. OPH solves these issues, and…

Medium