The universe is 14 billion years old, give or take half a billion years, according to a new estimate by cosmologists at the University of California, Davis, and Carleton College. The estimate is much more precise than previous calculations that had a margin of error of over 10 per cent.

To make the calculation, UC Davis cosmologist Lloyd Knox, graduate student Constantin Skordis and Carleton College astronomer Nelson Christensen measured the size of wrinkles in the cosmic microwave background, an afterglow of radiation from the Big Bang. Cosmologists think that the first stars and galaxies formed around these wrinkles, creating all the structure in the universe.

The older the universe, the smaller the wrinkles appear to be, Knox said. Previous calculations had relied on methods such as working backwards from the current density of the universe to infinite density, or measuring the ages of the oldest objects. Some of these calculations threw up answers that were clearly wrong, because the universe appeared to be younger than the oldest stars. All the previous estimates had wide margins of error.

Knox and colleagues sifted through a mass of data from recent experiments including the BOOMERANG high-altitude balloon and the Degree Angular Scale Interferometer (DASI) telescope near the South Pole.

"This is an example of the new era in cosmology where there is so much data that it pays to think hard about it," said Andy Albrecht, a cosmologist at UC Davis who was not involved in the work. "We're moving from pure theory to being able to test ideas directly."

The finding also provides evidence for cosmic acceleration, the idea that the universe is not just expanding but doing so at an increasing rate, said Albrecht.

Scientists should be able to make an even closer determination of the age of the cosmos within a year, using data from NASA's Microwave Anisotropy Probe (MAP) satellite, Knox said. Launched earlier this year, MAP will measure the microwave background across the whole sky.

Editor's note: Images of sky maps from the BOOMERANG mission are available at