Well, does it matter if protons are made of quarks? Does it matter that black holes exist in the center of galaxies? Almost certainly not in any sort of day-to-day way. Knowledge about the universe isn't a means. It's an end. A good goal, in and of itself.
The reference to someone going through the wall is almost certainly a (misleading) truth about quantum theory. Basically (and WAY over-simply), in quantum physics, a particle's position is determined by a probability wavefunction. In other words, you can imagine a particle on one side of a wall...
Hey, I'm just trying to make sure I understand the concept of hydrostatic equilibrium, so I devised two thought experiments that (depending on how they resolve) should really help clear up some confusion I have.
1. A tank of water, 1000 meters in the x and y directions but only 1 meter...