Satellite finds age of universe with new precision

A team from a longstanding NASA-Princeton collaboration announced Tuesday that scientists were recently able to obtain pictures of the early universe and answer many of the astrophysical questions that have puzzled scientists for years.

The project, which began in 1995, maps out the entire sky using microwaves — wavelengths of light invisible to the human eye — thought to be leftover from the Big Bang.

"This project allowed us to rule out many popular theories of how the universe came to be," University research assistant and project participant Licia Verde said. "We have not found the absolute answer, but we have taken a first step."

According to the collected data, the first stars were born 200 million years after the Big Bang, much earlier than the 800 million years scientists had preciously hypothesized, Verde said.

In addition to ruling out some hypotheses, the data reassured scientists of the accuracy of others.

"Many ideas about the universe were confirmed through this project," University research physicist and project senior research staff scientist Norman Jarosik said.

For example, he said, it was determined that the universe is flat and behaves according to the rules of basic Euclidian geometry — "the geometry you learn in high school," he said.

According to a University press release, the data also suggest the universe has been around for 13.7 billion years, plus or minus 200 million years.

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The information-collecting satellite the team is using is a medium class explorer, costing NASA $145 million.

This week, the team renamed it the Wilkinson Microwave Anisotropy Probe, in honor of Dave Wilkinson, one of the project's founding leaders and a member of the University's physics department until his death last year.

Many components of the project were constructed at the University. For example, the optics were designed and then tested on the roof of Jadwin Gymnasium, Jarosik said.

NASA used its expertise to assemble the spacecraft and determine communications. Princeton and NASA jointly analyzed the data, Jarosic said.

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The satellite was launched at the end of June 2001, and the released information spans only the first year of data, Verde said.

"There is a long series of projects that WMAP will be used for," Jarosik said. The satellite, which was initially scheduled for two years of research, has just received expanded funding and will be operated for four years.

"This is just the first data release of many," Jarosik said of the first year's results. "We are responsible to analyze and release this information to the public, but we are also responsible for releasing the maps so that people can analyze them on their own."

Jarosik said there is still much to learn.

Only four percent of the universe is made of matter we are familiar with, he said, and 73 percent of the universe is composed of dark energy and 23 percent is dark matter — matter that exerts a gravitational pull but does not emit or absorb light.

"So we really understand four percent of the entire universe," Jarosik explained.

Almost two dozen other University-affiliated scientists worked on the WMAP project, including physicist Lyman Page, astrophysicist David Spergel, postdoctoral researchers Christopher Barnes, Michael Nolta and Eiichiro Komatsu and graduate student Hiranya Peiris.