Unobservable

The reality of unobserables is closely related to epistomolgy, a term that generally means how one views the world, or their "theory of knowledge". Some argue that if a thing cannot be observed, it cannot be verified - hence the saying "if tree falls int he forest, and no one is around to hear it, does it make a sound?". One theory is yes - we have observed other trees fall and they made sounds, so that one did too. Others would say that one has no way of knowing if it made a sound or not because it was not observed.

The reality of unobservables, therefore, takes on a special and very important meaninging in the philosophy of science. Many of the recent innovations in theoretical, high energy physics is done through induction and inderect evidence - no one has seen quark or other subatomic particle; they are unobservable. But scients believe in the "reality" of the subatomic particles because of the evidence they have immassed to prove their theory.