The discussion centers on the concept of density as the mass-volume relationship and questions what occupies the space between atoms, given that atoms do not fully contact their neighbors. It suggests that the voids between atoms may be perceived as empty space. However, it is noted that mass/volume density is typically addressed on a macroscopic level, making the voids between atoms largely irrelevant in practical terms. The conversation highlights the distinction between atomic and macroscopic perspectives on density. Ultimately, the nature of atomic interactions and the significance of these voids remain complex and not fully addressed in conventional density discussions.