Cosmic Ingredients: Normal Matter, Dark Matter, Dark Energy

A surprising result of modern cosmology is that the stuff we are made of—atoms—accounts for only a small fraction of the universe’s total content. The rest appears to be dark matter and dark energy.

Dark matter does not emit or absorb light, but it pulls with gravity. It helps explain galaxy rotation, cluster dynamics, and the growth of the cosmic web.

Dark energy is even stranger: it is a name for whatever is causing the expansion of the universe to accelerate. We observe its effects through the behavior of distant supernovae and large-scale structure, but its true nature remains one of the biggest open questions in science.