I am not sure if that means that our notion of _time_ is completely broken. You're assuming an electron is a sphere, that goes like a tennis ball through one s

I am not sure if that means that our notion of _time_ is completely broken. You're assuming an electron is a sphere, that goes like a tennis ball through one slit, then goes back in time through another slit to interfere with itself. In Quantum Mechanics, there is no such thing as a _particle_ taking _this single path_. There is a continuum---that of the probability distribution of the position of the particle in a region of space, by the very axioms of QM. By definition, the statement "an electron exists here" has no meaning in QM.