When a photon produces an electron-positron pair, do both these particles have mass? Why or why not?

I had read from several sources that electric field inside a conductor is zero. This is attributed to the fact that the electrons are loosely bound to the nuclei and they are free to rearrange themselves until the net field becomes zero. But in an insulator the electrons are tightly bound to the...

This is from Pierre J. Clavier and Viet Dang Nguyen's paper Batalin-Vilkovisky formalism as a theory of integration for polyvectors. In section 2.3, it states: A symmetry is said to be open when it is fulfilled only on-shell, that is on the critical domain of the action $S_0$, i.e. on the subman...

The equivalence principal as I understand it goes something like this: Let's suppose you're in a black box in the middle of nowhere in space, and we accelerate this black box in some direction. You'd feel a force just like you would if you were in a gravitational field which was casing the same ...