relativity

We formulate a condition for the admissibility of parametrized trajectories in relativistic spacetime based on compatibility between worldline ordering and causal structure. A trajectory represents the history of a single physical system only if its parameter ordering agrees with the causal ordering defined by the spacetime metric. It follows that any trajectory for which this condition fails can…

Contemporary relationalism, most notably the program developed by Carlo Rov- elli, posits that time is not a fundamental dimension but an emergent effect of correlations between physical systems. However, this framework faces a significant ontological gap: the problem of insufficient specification of the conditions under which temporal order arises. By treating relations as generative of time, re…

In the context of Schwarzschild coordinates, a distant observer describes infalling matter as asymptotically freezing near the event horizon, due to gravitational time dilation and infinite redshift. ...

We challenge the common view that relativity and quantum formalisms compel a static block-universe ontology. Instead, we show that Existential Realism (ER) – can be formulated as an ontological extension of the specific physical models studied here, leaving empirical predictions unchanged so long as the added ER structure remains empirically idle. First, we clarify that the mathematical formalism…

Passionate about physics since my earliest childhood, I was dazzled when I read this statement : “In speaking of the Energy of the field, however, I wish to be understood literally. All energy is the same as mechanical energy, whether it exists in the form of motion or in that of elasticity, or... Read more

Check out the Universe in a Black Hole Merch at the Space Time Merch Store https://www.pbsspacetime.com/shop. Kurt Gödel discovered a solution to General Relativity that allows time travel without any exotic physics, revealing that the theory doesn’t actually guarantee a consistent chain of cause and effect. His “Gödel universe” shows that under certain conditions, the […]

These are solutions to Einstein's equations which are black holes in spacetimes that far away from the black hole are asymptotic (not to Minkowski spacetime but) to anti de Sitter spacetime. Under the AdS-CFT correspondence black holes in the anti-de Sitter spacetime translate to the conformal field theory on the asymptotic boundary being at positive temperature (e.g. Duff 99, section 6, Natsuume…

Physicists are rethinking one of quantum mechanics’ biggest puzzles: how fuzzy possibilities become definite reality. New research suggests that spontaneous “collapse” processes—possibly linked to gravity—could subtly blur time itself. This wouldn’t affect clocks we use today, but it reveals a hidden limit to how precise time can ever be. The findings open a new path toward uniting quantum physic…

In class, the prof. gave the following explanation for why the wheel precesses: Whenever the wheel is spinning, it has a angular momentum perpendicular to its face. The torque due to gravity changes the direction of the angular momentum, causing precession. However, this does not seem like a... Read more

This paper contends that if Lorentz covariance in General Relativity (GR) is claimed to be universal, the burden of proof lies with Einstein and his proponents to demonstrate its validity at the Planck scale. Based on the Logical Cost/Residual (LCR) framework, we argue that spacetime geometry is not a fundamental ontology but rather the result of "pruning" within underlying logical operations. Du…

Bizarre Hawking radiation may smooth the jagged hearts of black holes Adrian Cho https://www.science.org/content/art...adiation-may-smooth-jagged-hearts-black-holes Radiating black holes in general relativity need not be singular Francesco Di Filippo... Read more

Penrose's twistor programme, initiated in 1967, encodes massless fields through holomorphic structures on projective twistor space PT ≅ CP³. The Penrose–Ward correspondence gives a bijection between anti-self-dual solutions of the vacuum Yang–Mills and Einstein equations and holomorphic vector bundles over PT trivial on every twistor line, but naturally produces only one helicity sector. Completi…

The speed of light is not fundamental. It never was. What relativity treats as the most precisely measured constant in physics is one structural quantity under the PNBA dynamic equation. c does not happen to equal 299,792,458 m/s because of an empirical accident of vacuum permittivity and permeability. c is the propagation velocity at zero manifold impedance, which occurs uniquely at the sovereig…

A recent experiment revealed that individual dark points on a light wave can move faster than the wave itself

In this post , Peter Donis says: If an Alcubierre warp drive could actually be built (which, since it requires exotic matter, it probably can't), it would allow you to, for example, travel to Alpha Centauri in much less than 4.3 years, even as seen by observers on Earth or Alpha... Read more

The modern conception of the black hole, arising from the equations of General Relativity, presents us with a paradoxical entity: a region of spacetime defined not by substance, but by limit. It is a boundary condition—a locus where curvature becomes extreme, where conventional description falters, and where the known laws of physics approach their terminus. At its mathematical core lies the so-c…

A new recipe of "quadratic gravity" could help to better define the picture of the Big Bang and the singularity that existed prior to the dawn of time.

I pose this mostly as a question for people who understand more than I do. I would appreciate feedback for, or against this concept, so I can understand it better. I have not studied enough physics to be able to test this concept, or even know if it is original, but here goes. My... Read more

Imagine that there is a universe with no gravity (G=0), and the spacetime is perfectly flat. Suddenly a “fireball” emerges from a point and expands at the speed of light. This fireball is made of a ...