Looking Smart

So I caught myself explaining what I know about physics to a friend today, and it struck me that it felt like I was trying very, very hard to look knowledgeable. In the Tao te Ching, Lao Tzu said, "(S)He who speaks of a thing does not truly understand it."

Paradox aside, how can one explain something to someone without looking smart? That is, how do I explain physics to someone who isn't versed in it in such a way that it sounds like anyone could do it, instead of an intellectual elite?

>>13
Here again.

When talking about time travel, without going into detail about false vacuums, singularities, LHC, etc, it's next to impossible to not sound like a generic moron without going into huge detail.

Things like when talking to new people, "Yeah, I'm planning on becoming a physicist in high density physics and hopefully time travel."  People give you looks like you're a moron sometimes.