In a simplified cosmological simulation, giant elliptical galaxies are assumed to be distributed uniformly throughout space. In this model, the average distance between the centres of two adjacent giant elliptical galaxies of equal mass is 2.4×1022 m2.4 \times 10^{22}\text{ m}2.4×1022 m. Each galaxy is located at the centre of a cubical region of space with a volume of 5.8×1067 m35.8 \times 10^{67}\text{ m}^35.8×1067 m3.
An average giant elliptical galaxy in this simulation contains 8.5×10118.5 \times 10^{11}8.5×1011 stars, and the mean mass of an individual star is estimated to be 1.4×1030 kg1.4 \times 10^{30}\text{ kg}1.4×1030 kg.
Calculate the mass of an average giant elliptical galaxy.
Estimate the gravitational force of attraction between two neighbouring giant elliptical galaxies.
Calculate the mean density of the Universe predicted by this simulation.
Suggest why the actual mean density of the Universe might differ from the value calculated in (c).
