I have personally been deeply fascinated by the processes and principles that underlie the QED and have done some recent research myself. However, recently my teacher posted me a question that stunned me. He went,"Why do like charges repel and unlike attract?" In QED I understand that this is due to electromagnetic interactions between charged particles by exchanging virtual photons. However, what left me hanging in curiosity was how the virtual photons cause the difference between attraction and repulsion. Does it have something to do with the momentum of photons? And how does this translate to the macro world? Essentially, why do "unlikes" attract and "likes" repel?