Eigenstates of, for example, $\hat p$, are not elements of the standard quantum mechanical Hilbert space, i.e. $\psi(x)=e^{ipx}\notin\mathcal L^2(\Bbb R)$. This prompts the question of - given that after measurement the state of the system becomes one of these seemingly problematic states - how t...

If 'quantum foam'-generated particles are made of matter and antimatter in equal amounts, why don't the matter particles that fall into the black hole add to the black hole's mass just as much as the antimatter particles subtract from it? How, then, can the black hole evaporate due to Hawking rad...

I've got a ladder at some angle that is leaned on the wall. There is friction T1 and T2, and reaction forces R1 and R2. According to the rule that horizontal and vertical forces must equal 0 I've got result that R1 and R2 forces are independent on the alpha angle. Is it possible? Because it seems...