How would you go about estimating the size of the universe? Would you take the easy out and say it’s “infinite?” Would you, like a child expressing the degree to which they love a parent, stretch out your arms and say “thiiiisssssss big?” Given that, it’s a good thing we have the Baryon Oscillation Spectroscopic Survey (BOSS) Collaboration, who announced yesterday that they’ve accurately measured the scale of the universe to within 1%. Such precise measurements represent a key milestone in the understanding of dark energy.

“One-percent accuracy in the scale of the universe is the most precise such measurement ever made,” says BOSS’s principal investigator, David Schlegel, a member of the Physics Division of the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab). “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.”

The largest program in the third Sloan Digital Sky Survey (SDSS-III), BOSS uses the Sloan Foundation Telescope at the Apache Point Observatory in New Mexico. Recording spectra in over a million galaxies with redshifts between 0.2 and 0.7, it’s able to look over six billion years into the universe’s storied past.

By combining measures of Baryon acoustic oscillations (BAO), cosmic microwave background radiation (CMB) and supernova measures of accelerating expansion, the BOSS findings suggest that dark energy is a cosmological constant whose strength does not vary in space or time, not unlike Superman.

The authors of the BOSS analysis say that “understanding the physical cause of the accelerated expansion remains one of the most interesting problems in modern physics,” though it’s unlikely that the findings will lead to any disruptions in existing theories of relativity, including Einstein’s.

Other findings by BOSS suggest that though the universe isn’t flat, per se, it isn’t curved all that much, either.

“One of the reasons we care is that a flat universe has implications for whether the universe is infinite,” says Schlegel. “That 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 infinite universe.”

The BOSS analysis incorporates spectra of 1,277,503 galaxies and covers 8,509 square degrees of the sky visible from the northern hemisphere. This is the largest sample of the universe ever surveyed at this density. When complete, BOSS will have collected high-quality spectra of 1.3 million galaxies, plus 160,000 quasars and thousands of other astronomical objects, covering 10,000 square degrees.

The BOSS data are awe-inspiring,” says Martin White, “but many other pieces had to be put into place before we could get what we’re after out of the data.” Complex computer algorithms were essential for reconciling the inherent uncertainties. “We made thousands of model universes in a computer, and then observed them as BOSS would do and ran our analysis on them to answer the questions of ‘What if?'”

The party will end for BOSS in June of 2014, but fear not. Scientists have chosen now to complete their analysis because they believe that BOSS has captured around 90% of its final data. What lies in that final 10%? Aliens? Probably aliens.