Science Forums 2

[sanctus]

In QM you can see the electron as a probability wave, thatmeans that at every permitted orbit you have a certain probability to have an electron localized if you mesure it. The further away you the closer the energy levels get.
Now if I remember right you can apply the same reasoning to atoms, that means the the concept between atoms doesn't really have a meaning, they just have a probability to be somewhere (maybe as well delt-dirac like) but if you do not mesure them thay are sort of everywhere, what would imply that there is nothing in between. But now if you mesure their position then yes you got space between.