The Cosmic Microwave Background Is Leftover Glow From the Early Universe

In 1929 he found that distant galaxies are moving away from us faster the farther they are.

Roughly 27% is dark matter and about 68% is dark energy.

Scientists estimate this age by measuring the cosmic microwave background and the expansion rate.

Although the universe is about 13.8 billion years old, its expansion means the observable region is much larger than that age suggests.