So You Think Your Glass Is Half Full Or Half Empty?

Although long entrenched as a question asked in popular culture as a pop-psychology yardstick for gauging the perception of the optimistic or pessimistic personality type this is actually an unanswerable question.

Consider this before you answer this question the next time someone asks it of you:

Any container, by its own definition, has to contain something or it could be a container and there is no emptiness in a container. The space in the glass not being occupied by water, or any other visible substance, is still being occupied by something. In most cases this is simply air.

Air: atmospheric gasses and particles made up primarily of N2, O2, Ar, Ne and He and any possible combinations of substances not directly associated with the definition of air. These include free-traveling germs seeking hosts, enumerable light particles and microscopic wave factors.

So, is your glass half empty, half full or always full?