Hi, I applogise for the vague wording in the title but this is something that I've been thinking about for a while and I cannot get my head around it. The recent news item about Neutrinos possibly travelling faster than the speed of light got me thinking about this again. Suppose the Sun is replaced by a single atom and it generates a photon of light for whatever reason. In 8 minutes or so, a super sensitive detector would be able to detect that single photon on Earth. However, if there was a spacecraft at the other side of "the Sun" it will also detect that single photon. In fact, a detector at that same distance in any direction from "the Sun" would be able to detect that same photon. In this thought experiment we could extend this time to 10 billion years. In 10 billions years any super super sensitive detector could detect that same photon from any position relative to the original source of the photon. This 10 billion light year radius sphere would be massive indeed. I cannot even imagine how big the surface area would be. How can a photon be detected in any direction 10 billion years after it was emitted? What exactly is a photon?