Gravity

Gravity is dependent upon the density of matter not just the mass. For example, if we take a large gas cloud with a fixed mass (in other words a fixed number of molecules) and put it in a certain volume it will have a gravity magnitude corresponding to the density. If we were to take the same mass of the gas cloud and put it in a larger volume with equal mass distribution throughout the volume it would have a lower gravitational pull. Since the density of the mass determines the magnitude of the gravitational force so do the density of energy in that volume. Since matter is just a form of energy, therefore the gravitational force can be related to the density of energy in a given volume.