I don't see how this squares with Silas' claim that a 15-lb dumbbell hurts your hand when you rest it on it.
OK, I just tested this by balancing the end of a ~21 pound dumbbell on my palm while my palm rested on a counter (surface area of dumbbell end looks to be about 0.60 square inches, making the pressure around 35 psi, or about 2.3 atmospheres?) It was a little painful, but I didn't cry out or feel the need to get the thing off immediately. So in conclusion, I think Silas might have been exaggerating.
Resting my palm on a pillow instead of a counter, I don't really experience pain anymore, just discomfort. Maybe that has something to do with the fact that deep diving doesn't cause pain?
People's pain tolerances vary a lot.
There's a lot of background mess in our mental pictures of the world. We try and be accurate on important issues, but a whole lot of the less important stuff we pick up from the media, the movies, and random impressions. And once these impressions are in our mental pictures, they just don't go away - until we find a fact that causes us to say "huh", and reassess.
Here are three facts that have caused that "huh" in me, recently, and completely rearranged minor parts of my mental map. I'm sharing them here, because that experience is a valuable one.