Quantcast
Get breaking news alerts via email

Click here to manage your alerts
| Courtesy Zosia Rostomian, Lawrence Berkeley National Laboratory An artist's conception of the measurement scale of the universe. Baryon acoustic oscillations are the tendency of galaxies and other matter to cluster in spheres, which originated as density waves traveling through the plasma of the early universe. The clustering is greatly exaggerated in this illustration. The radius of the spheres (white line) is the scale of a ìstandard rulerî allowing astronomers to determine, within 1 percent accuracy, the large-scale structure of the universe and how it has evolved.
Researchers get most accurate measure of the universe
Scale » The new understanding likely will shed light on the nature of dark energy — the force that is causing the universe to expand.
First Published Jan 08 2014 06:18 pm • Last Updated Mar 24 2014 11:33 pm

Astronomers have defined the scale of the universe to within 1 percent accuracy, allowing them to better understand the enigmatic nature of dark energy and its ability to accelerate the expansion of the cosmos.

The Baryon Oscillation Spectroscopic Survey (BOSS) Collaboration is the largest program in the Sloan Digital Sky Survey-III, and researchers from the University of Utah contributed to its findings. The new measurement allows for a much more accurate picture of the universe and how it’s expanding.

Join the Discussion
Post a Comment

"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. "Twenty years ago, astronomers were arguing about estimates that differed by up to 50 percent. Five years ago, we’d refined that uncertainty to 5 percent; a year ago it was 2 percent. One-percent accuracy will be the standard for a long time to come."

BOSS involved scientists from across the country, including two U. scientists, Adam Bolton and Kyle Dawson, both assistant professors in the Department of Physics and Astronomy.

Bolton helped develop the software that allowed computers to analyze the light wavelengths from more than 1 million galaxies surveyed.

By looking at the light emitted from a galaxy, one can tell how far away it is because of the Doppler effect. In essence, it’s like hearing an ambulance siren: the faster it’s moving, the lower the pitch. The same is true for lightwaves, and scientists were looking at red-shift variations because the visible light spectrum stretches from blue to red.

"Our universe is expanding from the Big Bang, and those galaxies and stars and quasars that are farther away move away faster and are shifted toward longer wavelengths," Bolton said.

The gravitational pull of all of the galaxies in the universe should mean that the universe would be contracting. However, the universe is expanding, and doing so at an increasing rate. Scientists now say that expansion is being propelled by dark energy, but they don’t have a clear understanding of exactly what dark energy is. They hope this new measurement will help them better understand its behavior and its effect on the universe’s expansion.

When the universe was forming about 13.7 billion years ago, it started as electrons and protons. Eventually, it cooled down enough that galaxies could begin forming. The locations of where those galaxies formed depended on the density of the matter in locations throughout the universe. If one area was even slightly more dense than a neighboring area, galaxies would group together in those dense areas because of gravitational forces pulling in on each other.

"Small distinctions from the early universe begin to get amplified, and you have areas that have lots of galaxies and some that don’t have galaxies," Bolton said. "Length scales of the characteristics between those very early overdensities and underdensities are preserved and propagated down to present day. The relative density between these regions have been amplified greatly."


story continues below
story continues below

By measuring the Baryon acoustic oscillations — basically densities as indicated by the light wavelengths emitted — researchers were able to create a "standard ruler" for distances in the universe — though it’s in millions or billions of light years as opposed to inches or meters. The new measure will allow astronomers to create better models to understand how dark energy is accelerating the expansion of the universe, said Dawson, who oversaw the steps ranging from equipment at the observatories to getting data to scientists.

"What we want is the underlying model that describes that behavior, that’s the fundamental purpose," Dawson said.

Much like trying to understand the weather history in the desert by looking at the rings of a tree, the survey looks at galaxies from different epochs. This portion of the survey looked at galaxies that existed when the universe was about 8 billion years old; the light from those galaxies took about 5.5 billion years to reach Earth’s observatories, Dawson said. The goal is to be able to go back to 12 billion years ago.

The U. will have an even larger role in SDSS-IV, which is planned to begin in summer of 2014.

smcfarland@sltrib.com

Twitter: @sheena5427



Copyright 2014 The Salt Lake Tribune. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

Top Reader Comments Read All Comments Post a Comment
Click here to read all comments   Click here to post a comment


About Reader Comments


Reader comments on sltrib.com are the opinions of the writer, not The Salt Lake Tribune. We will delete comments containing obscenities, personal attacks and inappropriate or offensive remarks. Flagrant or repeat violators will be banned. If you see an objectionable comment, please alert us by clicking the arrow on the upper right side of the comment and selecting "Flag comment as inappropriate". If you've recently registered with Disqus or aren't seeing your comments immediately, you may need to verify your email address. To do so, visit disqus.com/account.
See more about comments here.
Staying Connected
Videos
Jobs
Contests and Promotions
  • Search Obituaries
  • Place an Obituary

  • Search Cars
  • Search Homes
  • Search Jobs
  • Search Marketplace
  • Search Legal Notices

  • Other Services
  • Advertise With Us
  • Subscribe to the Newspaper
  • Access your e-Edition
  • Frequently Asked Questions
  • Contact a newsroom staff member
  • Access the Trib Archives
  • Privacy Policy
  • Missing your paper? Need to place your paper on vacation hold? For this and any other subscription related needs, click here or call 801.204.6100.