MacM: In one sentence you say the muon's proper time changes in its own frame. In the next, you say the muon can't detect any such change. Which is it? Poor confused MacM. Poor MacM. No model. Just a muddle. Your second post above makes my previous careful explanation to you a complete waste of my time. I will be wary of wasting my time in future explaining things to you, if this is the type of response I get.