Yes. In philosophy class. Descarte I believe. Everything could be an illusion. But I never applied this to physics. More metaphysical. It's interesting to think about, but I find this sort of thinking leads to a lot of dead ends and rarely any practical experiments or uses in "real life" (or rather the "big illusion" if you prefer). ::update:: oops... the response below for vx220... As far as time = motion. I see that we have a fundemental difference of opinion that can not be resolved. I feel the universe would exist even if it didn't exist in our minds and that there are potentially portions of the universe which exist forever outside our observation. I believe these loctions are real and experience time without our observation. I believe complete destruction of the earth does not mean the end of universal time... even if we were to be the only life in the universe. But I see I'm not going to convince you. Your view is as valid as mine. It would be nearly impossible to disprove your argument (or prove mine) in experiment, but now I see where you're coming from.