A short list

Facts

A compact reminder. The longer wording, and the disagreements, are on the topic pages and in the fact-check log.

A widely held theory

The big-bang model describes the emergence of the universe from a state of extremely high temperature and density, 13.8 billion years ago, in Britannica wording.

No centre

The origin occurred not at a particular point in space but throughout space at the same time. John Mather puts it: the universe doesn’t have a centre.

An expanding universe

Vesto Slipher’s redshifts and Edwin Hubble’s correlation provided evidence that the universe is expanding.

The leftover glow

The cosmic microwave background was discovered in 1965 by Arno Penzias and Robert Wilson. It is the oldest light we can observe.

When atoms formed

Several NASA pages use about 380,000 years; WMAP’s overview uses about 375,000; Britannica’s model article uses about one million years later.

The first nuclei

Hydrogen, helium and lithium. A NASA page places this a few minutes after the big bang; Britannica says after a few seconds.

Inflation

A brief, rapid expansion, faster than light, whose trigger remains unknown.

Today’s census

In NASA’s WMAP wording, about 5% ordinary atoms, about 25.0% dark matter, and about 70% dark energy.