I have recently read Richard Feynman's "QED" and in it Feynman describes positrons as 'how we view electrons when they are going back in time and we are stuck traveling forwards in time'. I was wondering, are all positrons electrons traveling back in time? Or can you have an electron with a positive charge (positron) that is not traveling backwards? Furthermore, if all positrons are (from a quantum dynamics standpoint) traveling backwards in time, then why (again from a quantum dynamics standpoint) would an element, such as Fludeoxyglucose (18F) emit these positrons so much more than other elements?
Thanks a bunch! I hope I was clear with my question, if not please let me know.