Dark Matter Week

The term “dark matter” is just the name scientists give to a missing ingredient in our understanding of the Universe. Although dark matter is a mystery, we know it formed very early in the history of the Universe, as it seems to have been present when the Universe was only(!) about 400.000 years old. Like stars and gas, dark matter is not evenly distributed in the Universe. In the past, areas of the Universe that had a little more dark matter (and therefore more gravitational pull) attracted more matter, giving rise to the distribution of galaxies that we see now. Dark matter does not emit, absorb or reflect light. It also does not interact with other known particles, such as electrons and protons. Dark matter is so unreactive that it may not even interact with itself! Although dark matter has a famously standoffish reputation, it is the invisible glue that holds galaxies together.