The Doctor’s vices hedonic
Made him a holo-syntheholic,
Who abused without fail
His favorite cocktail:
Replicated gin and faux tonic.
On Voyager, the Doctor was an emergency medical hologram (EMH), a sentient computer program given form through holographic projectors that allow him to interact with the ship’s crew and objects in the physical world. The joke here is a play on words, “faux tonic” and “photonic.” So, it begs the question: does a photon (or theoretical graviton) have mass? After all, how can a strong magnetic field act upon it unless it does? Think black hole absorbing everything, even light, as we all learned in high school. Like all answers to complex questions, the answer is “yes,” “no” and “it depends.” Though a photon carries momentum (since it does grow more massive as it accelerates toward the speed of light or c) and will exert pressure on a surface (quantified classically as radiation pressure), it has invariant mass of zero (that is, rest mass), but one could say it has relativistic mass, though this concept has largely fallen out of favor, since the particle is always moving at c or some fraction of it). The reason light enters black holes is not because gravity sucks it in, but rather because photons follow a geodesic path along the black hole’s curvature of spacetime. Light circles like water around a drain as it flows “down.” Once beyond the event horizon (or apparent horizon, as Hawking now calls it), it is too dim to perceive. Or something like that. I’m a humorist, not a fucking theoretical physicist! —Stumpy
