Scientists Make Most Accurate Measurement of the Universe to Date: One Percent

How big is the universe? That's a good question, and scientists may have found out. They've measured the scale of the universe to an accuracy of one percent, a finding that could be key to determining the nature of dark energy.

"One-percent accuracy in the scale of the universe is the most precise such measurement ever made," said David Schlegel, one of the researchers, in a news release. "Twenty years ago astronomers were arguing about estimates that differed by up to fifty percent. Five years ago, we'd refined that uncertainty to five percent; a year ago it was two percent. One-percent accuracy will be the standard for a long time to come."

So how did the researchers manage to make such a precise measurement? Since 2009, the researchers have used the Sloan Foundation Telescope to record high-precision spectra of well over a million galaxies with redshifts from .2 to .7, looking back over six billion years into the universe's past. In fact, they plan to continue collecting data until June 2014. Yet so far, they've collected 90 percent of the final data.

Baryon acoustic oscillations (BAO) are the regular clustering of galaxies. This scale provides a "standard ruler" to measure the evolution of the universe's structure. Accurate measurement can dramatically sharpen our knowledge of fundamental cosmological properties, including how dark energy accelerates the expansion of the universe.

So what do these new results show exactly? Combined with recent measurements of the cosmic microwave background radiation (CMB) and supernova measures of accelerating expansion, the results reveal that dark energy is a cosmological constant whose strength does not vary in space or time. In addition, the researchers were also able to make one of the best-ever determinations of the curvature of space; it turns out that, in fact, it's not curved much.

"One of the reasons we care is that a flat universe has implications for whether the universe is infinite," said Schlegel in a news release. "This means--while we can't say with certainty that it will never come to an end--it's likely the universe extends forever in space and will go on forever in time. Our results are consistent with an infinity universe."

The findings are published in the journal Monthly Notices of the Royal Astronomical Society.