I'm guessing we are using a useful version of pass through where we do not insist that we have an infinite thickness of medium where nothing can pass through.
Anyways, a finite amount of lead can not completely block off light. Fire enough photons at it and eventually one will be lucky enough to get through.
Indeed. The most powerful one was the so-called EPR paradox. It was conducted. Einstein was shown to be wrong.
Ah well. And that's the end of that.
Photons and wave theory are two sides of the same coin. Physics usually mean "em radiation" when they say light.