theory-of-relativity

On KK-compactification of 11-dimensional supergravity on a squashed 7-sphere with G₂-holonomy (M-theory on G₂-manifolds): On Kaluza-Klein compactification in supergravity: Mike Duff, Bengt Nilsson, Christopher Pope, Kaluza-Klein supergravity, Physics Reports Volume 130, Issues 1–2, January 1986, Pages 1-142 (spire:229417, doi:10.1016/0370-1573(86)90163-8) Michael Duff, Bengt Nilsson, Christopher …

Michael Duff is professor of theoretical physics at Imperial College London. He made foundational contributions to string theory and M-theory. Autobiographical notes around encountering Chris Isham: See also: 478 (2022) 2259 [doi:10.1098/rspa.2022.0166] On KK-compactification of 11-dimensional supergravity on a squashed 7-sphere with G₂-holonomy (M-theory on G₂-manifolds): Moustafa A. Awada, Mike…

Bengt E. W. Nilsson On Kaluza-Klein compactification in supergravity: Mike Duff, Bengt Nilsson, Christopher Pope, Kaluza-Klein supergravity, Physics Reports Volume 130, Issues 1–2, January 1986, Pages 1-142 (spire:229417, doi:10.1016/0370-1573(86)90163-8) Michael Duff, Bengt Nilsson, Christopher Pope: Kaluza-Klein Supergravity 2025, in: Half a Century of Supergravity – Part II: Structure and Prop…

I don't see how special relativity is necessary to explain the Michelson Morley null result. Surely the simplest solution to the experiment was just to abandon the aether, and continue using Galilean ...

What seems like bending the laws of physics is actually just using them to our advantage.

A quantum “mini universe” made from ultracold atoms revealed that time can emerge from entropy changes inside a system, offering experimental insight into one of physics’ deepest mysteries. A scientist at the University of Birmingham has created a “mini universe” that could help answer one of science’s most fundamental questions: What is time? In a [...]

Can humanity ever travel faster than light, or does every shortcut through spacetime break causality itself? We explore warp drives, wormholes, tachyons, and why the universe pushes back. Get Nebula using my link for 50% off an annual subscription: https://go.nebula.tv/isaacarthur. Watch my exclusive video Nearby Supernovae: https://nebula.tv/videos/isaacarthur–… SFIA Merchandise: https://isaac-a…

General Relativity and Quantum Cosmology Title:Semiclassical Gravity Efficiently Solves $\mathsf{NP}$-Complete Problems View PDF HTML (experimental)Abstract:Assuming the gravitational field is classical and that it couples to quantum fields via the semiclassical Einstein field equations, we show that the weak-field dynamics of a massive and non-relativistic qubit can in principle be used to solve…

This paper completes the triptych on black holes in Transformative Semalgebraic Ontology (OTS). The first panel treated the event horizon topologically, as the boundary of outward inactualisability. The second panel treated the event-horizon crossing dynamically, as the irreversibility of actualisation seen from outside. The present panel treats the four magnitudes that make the black-hole case a…

We think of atomic clocks as the definitive timekeepers. They are famous for being accurate down to the picosecond. Unfortunately, they are still subject to general relativity, so if you put them on a different planet, they will track time slightly faster or slower than on Earth, depending on the planet’s gravity. In Mars’ case, an atomic clock on its surface is sitting in a slightly shallower gr…

Landau & Lifshitz introduce what are known as Lemaître coordinates (the coordinates and associated Schwarzschild metric were first used by G. Lemaître in 1932-1935). The figure (Figure 20) on p. 310 is a magnificent illustration of why all timelike and null paths within the black hole region... Read more

As was repeatedly shown by Anders Persson, https://rmets.onlinelibrary.wiley.com/doi/10.1002/qj.2477 http://rus.ums.rshu.ru/file1654 the "carousel experiment" is a poor case to show the Coriolis force despite claims it show the "Coriolis effect". Indeed, the Coriolis force, if it... Read more

This piece was published in 1921, so five years after Einstein wrote "Relativity: The Special and the General Theory" for a general audience... Read more

I would like to explain to someone about why the Sun's gravity does not pull the Earth into the Sun. I know that the reason that the Sun's gravity does not pull the Earth into the Sun is that the momentum of the Earth orbiting the Sun is in equilibrium with the Sun's gravity. What I need to... Read more

I solved gravity After deconstructing the complexities of general relativity and tensor calculus, I have developed a single, unified F= equation that accurately calculates gravitational force across all environments from gravitational orbits to Mercury's precession, and super massive... Read more

Einstein’s famous equation has grown into one of the great symbols of the 20th century. It is the one equation in science that people recognize, if any is. It has a kind of iconic status and dual connotations: the brilliance and insight of Einstein and the darkness of atomic bombs. Images. The basic idea behind […]

New claims challenge inconsistencies in one of the foundational principles of physics.

New research says time only exists where space is curved enough to support it, implying that our expanding universe is slowly losing its grip on time itself.

A humble elevator shaft was recently used in a test of the constancy of the speed of light. Credit: Jason Wong/Flickr , CC BY-NC-ND 2.0

Extremely curved spacetime can warp cause and effect, creating channels for backward communication