I appologize if my questions make no sense (very likely as I do not have a physics background). 1. The uncertainty principle states that precision of measurement is identified only down to the Planck's constant. If this is so, how can one measure the speed of light with infinite precision? ANd then how can one claim that such a number (constant) exists? 2. If a beam of light goes through a small hole and then hits a screen, one gets the Airy pattern. Suppose one can measure the time between (a) when a photon is emited and (b) when the photon hits the screen beyond the hole. Whould the time measured depend on where the photon ends up on the screen behind the hole? Constant light speed suggests that it should take longer for photons that hit farther away from the middle of the screen. Is that true or am I missing something?