I want to study a QFT, given by an action $S$ which is defined in $(2+1)$ dimensions, i.e. $$ S=\int d^3x \mathcal{L}[\phi,\,\partial\phi]. $$ This QFT is invariant under rotations, i.e. in radial coordinates $r=\sqrt{x^2+y^2}$ and $\theta=\tan^{-1}(y/x)$, the action is invariant under a transfor...

for some context: I was self-studying and got confused about this question. This is a past paper question from the CAIE O Levels Board and its reference code is shown in the image attached below. I don't need help with the actual question, but rather the underlying concept. My Thinking: As seen i...

If an object is accelerating when it enters water, will the buoyant force equation be changed to $B = V\rho(g + \text{acceleration})$? Or will it remain the same?

I am all the time reading that gravity is actually the curvature of spacetime according to General Relativity established theory and not a force like the known three fundamental forces of nature, Electromagnetism, and the strong and weak nuclear quantum forces. However, my intuition says, that th...