Are kids natural born physicists?

While walking to the park my daughter, walking ahead, looked down, pointed and said "Mommy, Daddy, look! My shadow!" Lori, then quizzed, "Mason, what's the difference between a shadow and your reflection". Mason, gave a barely a moment's thought, and said "There's no light."
Of course, when you think about it, it's a perfect text book answer. It may be possible that she was taught the definition at day care, and not really some miracle child, but in any case an answer like that coming from a three year old was enough to blow us away.