Sound is created by the displacement of air. A tree falling displaces air as it plummets towards the ground. When it makes impact, it displaces a lot of air.
This notion that a thing isn't real unless perceived by humans is quaint, at best. It explains a lot about our relationship with the world around us.
If you stop pouring long enough to measure, the glass is half-full. If you stop drinking for that same purpose, it is half-empty. It is halfway to it's desitination.
This is, of course, an approximation. Measured with enough precision, you'll always find it to be slightly over in one direction or the other. If not, wait a few minutes for evaporation and condensation to work their magic.
That said, there's nothing inherently optimistic or pessimistic about how one views a glass of water. To someone drinking their recommended 64 ounces each day, "Half-Full" could mean discomfort, with more to come. Depends how big the glass is, and how many they've already had. We can't assume infinite thirst on the part of the observer.
Further? MY glass contains water, Diet Coke, or whatever else I might be drinking. YOUR glass contains only cooties.
If you believe in an infinite God, why is it so hard to accept that there are things about him you'll never comprehend? Of course he can create a rock so heavy that even he can't lift it. And yes, he can certainly lift that rock. It's not a contradiction.
(seriously, pick any concept out of science-fiction or fantasy. if a genuinely religious person tells you it's not possible... re-classify them as something else)
Yes. That dress, those pants, whatever you're holding up... They absolutely make you look fat, and I can tell you this without even looking. If it was flattering, you wouldn't have asked -- trust your instinct.