Now, what types of interactions will we find between those non polar side chains? Well, the interactions are known as London Dispersion Forest. It's also known as Van der Valal interactions. And these are the interactions that exist between the instantaneous dipole moments on those non polar side chains. And even though on an individual basis, these instantaneous dipole interactions might be very weak, because we have many of these non polar side chains in the core, we have many of these vandervals interactions. And that aggregate creates a relatively substantial effect that binds those amino acids in the core together and holds them in place so that they are away and don't interact with the water molecules found in close proximity outside of that protein.