The Cosmic Accounting: Curved Space-Time, Dark Energy, and Dark Matter

The universe is mostly made up of invisible stuff, with visible matter only accounting for about 5%. The majority of the energy matter content is dark energy, which is affecting how space-time expands. Dark matter, on the other hand, gravitates exactly like visible matter but is completely different in every other way. It does not have a color and light seems to pass right through it. Dark matter dominates the outskirts of galaxies and affects stellar motions on the edges. The presence of dark matter is also affecting how galaxies are distributed throughout space-time. While we know something about the amount and distribution of dark matter, we do not know what kind of particle it is. It is unlike any of the particles we have ever seen. Understanding dark matter is not just an astrophysics problem, but also a particle physics problem.