So scientists are finding that the Universe is expanding at an accelerating rate. It is said 'Dark Energy' is the cause. Ok. But the Universe expanded at a reaally accelerated rate just after the Big Bang too! Presumably at a faster rate then 'now' (whatever time the observations stem from) So, i...

I took a course on GR and I am revising it after a while. I am heavily confused about the equivalence principle. Consider the following two statements: On a Riemannian manifold, we can always choose coordinates such that the metric looks like the Minkowski metric ($\eta_{\mu\nu}$) locally. From...

I guess absolute time is associated to classical mechanics because people like Newton believed in that concept, but are there actually any statements whose derivation is based on this assumption? I've looked into the Noether's theorem and some proofs regarding the Lagrange equations and it didn't...

The goto answer to that question is that the electron is a pointlike particle and cannot spin. The electron is not pointlike though. It is described by a wavefunction. One can prepare the wavefunction to describe a very small electron, but not a point-like electron. Is there a genuine answer to t...