The Interconnectedness of the Universe.

The Universe's matter is composed of elementary particles that exist within spacetime. Over time, gravitation collects and collapses neutral gas clouds, forming stars, which grow and merge to form galaxies, galaxy groups, and rich clusters of galaxies. However, dark energy prevents these structures from remaining stable, driving them apart and fragmenting them as time goes on. The individual groups-and-clusters are not gravitationally bound together and are receding from one another as dark energy dominates the cosmic expansion.