system
Given the following post, respond as if you're commenting on Reddit:
human
If we are 99.9% empty space, along with everything else - Why can't we see through each other and see through walls?
gpt
The oft quoted "empty space" idea is describing the space in between the electron shells and the nucleus, which is inside the atom.

However, if you get light with a short enough wave length then we can see through things. That's how x-rays work!