Something like a decade ago, my husband sent me an email very like "Is there a Santa? A Physicist's View." Wow, talk about a killjoy, even if you aren't old enough to work out the math for yourself.
But then it occurred to me: Why does Santa have to operate on classical principles of physics? True, St. Nicholas of Myra lived during the 4th century--well before even Newton (much less Einstein, Planck, Heisenberg, Schrodinger and company), but that doesn't mean that matter and energy operated any differently in the days when folks were still looking back to Classical Greece for their science.
Quantum mechanics--among other mind-bending principles--holds that it is impossible to verify the properties of things which cannot be measured: Everything boils down to probabilities. That enables the concept of something existing in more than one place or state at one time. And you will recall, of course, that we are never, ever supposed to actually see Santa Claus on Christmas Eve. That is a paramount tenet of Clausology. (Clement C. Moore was either cheating or lying through his teeth!) Moreover, much of quantum physics revolves around uncertainty (particle or wave? position or momentum?). Just as there is always a fundamental uncertainty to the existence of Santa Claus--otherwise, generation after generation of children wouldn't ask "Is there really a Santa Claus?"
Coincidence? I, for one, think not.
The only rub lies in the fact that by the time you're old enough to have enough physics to appreciate (even if only superficially, like I do) the differences between classical, relativistic and quantum physics (particularly in terms of scale), you're probably too old for Santa to visit any longer. But, then, you're likely old enough to be your own Santa Claus. In any case, it's not like the Universe will run low on mysteries anytime soon...
