The Universe's Budget

The cosmic inventory is humbling. Of everything in the universe, 68% is dark energy, 27% is dark matter, and only 5% is ordinary matter. Every star, planet, gas cloud, and living thing we have ever directly detected fits inside that slim 5% slice.

Dark energy also grows with the universe: as space expands, it brings more dark energy, which speeds the expansion up even more. Over vast stretches of time, this runaway effect may push galaxies so far apart that future civilizations never know other galaxies existed.