While on a short stay in hospital last week I had too much time on my hands to think. One particular train of thought led me to a very startling question. Is there any mechanism, any theory or any indication that protons and electrons can exchange polarity. I.e., protons become negative and electrons positive. I have never come across such a possibility being discussed within the standard model and can't find much (well nothing really) on it in the literature. Can anyone say that they have come across this question before and how it was treated. Thanks.