I am thoroughly enjoying Richard Dawkins' new book The Greatest Show on Earth. This is perfect science writing for someone like me. I'm learning a lot, but the book is a pleasure--not the least bit like doing more work at the end of the day. The title is apt--in fact, I feel like I'm at a show. The marvels of nature are being paraded before me, and they truly are marvelous.
But now, what's this? A paragraph that isn't actually crystal clear (p. 92).
When we look at a solid lump of iron or rock, we are 'really' looking at what is almost entirely empty space. It looks and feels solid and opaque because our sensory systems and brains find it convenient to treat it as solid and opaque. It is convenient for the brain to represent a rock as solid because we can't walk through it. 'Solid' is our way of experiencing things that we can't walk through or fall through, because of the electromagnetic forces between atoms. 'Opaque' is the experience we have when light bounces off the surface of an object, and none of it goes through.If the rock is mostly empty space, why do we see the particles, not the empty space? Well...good question! It doesn't seem as if Dawkins is explaining this well. Surely it's not just convenient to represent the rock as solid, but actually impossible to see that empty space. But...why? If we can see the particles, why can't we see the empty space? I bet some smart person out there can improve on Dawkins' explanation.