Mr. Jeliss, - I also forgot to address your math point. - The context of the discussion was in dealing with physical models, in which time is typically treated as an exponent. Then you have a system that simply becomes infinitely small as you move the dial into the negative numbers. (Oversimplification, but the algebraic property is right.) - More intriguing to me is the use of complex numbers in quantum physics... that's an entire black box to me right now. Much math to study... too little time.