The universe has been busy

Several kinds of evidence point to a hot, expanding early universe.

FIGURE 5 / Left: major events, with gaps not drawn to scale. Right: estimated shares of today's cosmic energy budget, including matter. [1-3]

Cosmic expansion, light-element abundances and the microwave background provide independent constraints. [1-3]

A hot early universe is described by standard cosmology. Its fitted age is about 13.8 billion years. [1-3]

Predicted patterns and element abundances are compared with observations. Agreement across different measurements strengthens the model.

Dark matter and dark energy describe inferred components. Their physical nature, and the ultimate cause of the early state, remain unresolved.

Giving a mystery a name does not finish the paperwork.

First minutes Light nuclei

380,000 years Atoms; ancient light released

First stars Hundreds of millions of years

9.2 billion years Solar system forms

13.8 billion years Present epoch

Ordinary matter 4.9%

Other matter 26.6%

Dark energy 68.5%