relativity

this question is a modified version of my previous question:https:[//physics.stackexchange.com/q/875717/589276] Consider the coordinate system S'. In the S' frame, there is a uniform magnetic field of magnitude B' in the x'y'-plane. The magnetic field lines are perpendicular to the x'y'-plane and point outward from the plane. There is also a uniform electric field E' in the x'y'-plane, directed d…

A Lorentzian manifold is called globally hyperbolic if it admits a well-defined time evolution from initial data of physical fields on it. There are several equivalent definitions of global hyperbolicity. A simple one is: A Lorentzian manifold (without boundary) is called globally hyperbolic if it contains a Cauchy surface. In this form the characterization of global hyperbolicity appears for ins…

Consider the coordinate system S'. In the S' frame, there is a uniform magnetic field of magnitude B' in the x'y'-plane. The magnetic field lines are perpendicular to the x'y'-plane and point outward from the plane. There is also a uniform electric field E' in the x'y'-plane, directed downward.In the x'y'-plane, there is a rigid conducting loop as shown in Figure. The sides a,b,and c are fixed, w…

Scientists have observed a long-predicted effect of gravity on a falling quantum object for the first time. The experiment suggests that a key principle in Albert Einstein’s theory of gravity also applies to matter governed by the strange rules of quantum physics. The international study, which included Nobel Prize-winning physicist Professor Sir Roger Penrose, was […] The post Scientists See Ein…

Scientific Reports, Published online: 06 September 2026; doi:10.1038/s41598-026-69947-9 Two scale black holes with a phenomenological suppression profile: extremality, null critical curves, and test field spectra

The Autocremation Paradox (ACP) is a thought experiment designed to close the redundancy problem of the bootstrap paradox. Where standard loops persist an unchanged object or a piece of information without origin, the ACP lets the thermodynamic remainder of an event—the ashes of a cremation—function as the material cause (propellant) of that same event. The resulting State-Change Identity makes t…

Heisenberg said extreme magnetism would make nothingness bend light. A dead star just proved he was right.

On the global structure and spacetime topology of Kerr-Newman-Reissner-Nordström spacetimes (and making explicit their 2-sphere topology): Brandon Carter: Global Structure of the Kerr Family of Gravitational Fields, Phys. Rev. 174 (1968) 1559 [doi:10.1103/PhysRev.174.1559] (including observation that the gyromagnetic ratio of the Kerr-Newman black hole is 2, just as the for electron cf. at anomal…

The Focusing Theorem from General Relatativity states that if the Strong energy condition is satisfied ( $R_{\alpha\beta}u^\alpha u^\beta\ge 0$ ), then the expansion parameter $\theta$ of a congruence of timelike geodesics (which, roughly, gives the fractional rate of change of volume of the local fluid ensemble around a refernce fluid particle) that is hypersurface orthogonal has a negative rate…

Directly visualising the inherent uncertainty within empty space has long remained an elusive goal. Now, images from a Bose, Einstein condensate reveal spatial patterns arising from quantum vacuum fluctuations, a feat previously limited to observing their indirect effects via electromagnetic sampling. This system uniquely emulates a massive relativistic sine-Gordon field, enabling laboratory stud…

In the initial kinematics of Special Relativity the rod clocks are synchronized to the stationary system clocks, then Einstein sends a light from A to B and back to A that shows TAB≠TBA How does he then justify claiming the clocks are not synchronized instead of the time of flight of light in the rod frame is not the same from A to B as it is from B to A?