Atoms are mostly empty space, and although I now understand why matter doesn't pass through other matter, why don't photons pass through the empty space of the atoms? Is it the same sort of idea as matter passing through other matter?
They taught me that in high school too (i.e., that matter is "mostly empty space.") Only thing is, it's not true.
Solid matter is mostly filled with electrons. Yeah, the mass is all concentrated in the relatively tiny nucleii, but the mass is not what photons interact with, and the mass is not what defines the physical and chemical properties of ordinary matter. The electrons are responsible for all of that, and the electrons pretty much fill the space.