If it is only a "notion" and not based in fact, only what people believe, then it is not real.

If you don't take your theory and do some research and some experiments to prove your theory right or wrong its it still just a theory.

Saying something is real because of a theory that supports your idea is the same thing the therians do. Nothing based in facts for any of it but because someone said a theory that agrees with me it must be true. -smh-