COSMOLOGY

101 · zoom in

Cosmology — the universe at large, and how we know its size.

Zoom out far enough and the individual galaxy stops mattering. What comes into view is structure: galaxies gathered into groups, groups into clusters, clusters strung along filaments and sheets that wrap around near-empty voids — the cosmic web. This tab is about that largest scale, and about the measuring chain that lets us put honest distances on it.

It pairs with the outer shells of the /explore scale ladder. When you climb past the Local Group into the Local Sheet, the Virgo Supercluster, and beyond, these are the articles that explain what you are looking at and how anyone could possibly know how far away it is.

The set grows with the ladder: large-scale structure and the distance ladder land first, with the Virgo Supercluster; the deeper cosmology — redshift and Hubble's law, dark matter and dark energy, the microwave background, the Big Bang itself — arrives alongside the tiers that need it.