11 January 2014

Astrophysicists create the first accurate map of the universe: It’s very flat, and probably infinite

After analyzing more than three years of continuous observations from one of the world’s widest-angle telescopes in New Mexico, astrophysicists have compiled the most accurate map ever of the universe. Spanning a distance of over six billion light years, the new map plots the location of 1.2 million galaxies with an accuracy of 99%. This means that the distance between galaxies on the map is accurate to within 1% of the actual distance an astonishing feat when you consider that we’re doing the measuring from a single point of space and observing tiny specks of light that are trillions of miles away. The new map provides some of the best evidence that the universe is flat, and that it’s “likely” the universe is infinite, extending forever into space and time.

This new map was created from the BOSS – Baryon Oscillation Spectroscopic Survey which is one of the projects being carried out by the Sloan Digital Sky Survey III on a 2.5-meter wide-angle reflector telescope at the Apache Point Observatory in New Mexico. The BOSS, which probably has the coolest name in all of science, stares up at the night sky looking for baryon acoustic oscillations waves of particles and energy that were created when the universe was young, and continue to spread like ripples in a pond. Without getting too deep into the physics of it, at some point during the universe’s formative years, an overdense region of primordial plasma exploded outwards, sending baryons (another word for protons and neutrons) out into space. Because these baryon waves move at a standard speed, it’s possible to use them as a very accurate intergalactic ruler (measuring almost exactly 490 million light years in this case). With this ruler in hand, BOSS can rather accurately map where galaxies are located in the universe.

An artist’s rendition of the BOSS galactic map

“Twenty years ago astronomers were arguing about estimates that differed by up to 50%. Five years ago, we’d refined that uncertainty to 5%; a year ago it was 2%,” BOSS chief investigator David Schlegel of the Lawrence Berkeley National Laboratory told the BBC. “One percent accuracy will be the standard for a long time to come.”

At this point you’re probably wondering what we can do with a 99%-accurate map of the nearby universe (yes, this isn’t a map of the entire universe 1.2 million galaxies is just a tiny sliver). Will it be used by NASA to plot its first intergalactic mission? No (but it’s nice to dream). A highly accurate galactic ruler and map is useful for one main reason: It tells us a lot about how the universe actually functions. If you have an accurate galactic ruler, it then becomes fairly easy to work out whether the universe is flat or curved, and whether the universe is static, expanding, or contracting. [Research paper: arXiv:1312.4877 - "The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: Baryon Acoustic Oscillations in the Data Release 10 and 11 galaxy samples"]

Not a map of the universe, but the core of the Milky Way, as seen by ESO’s VISTA telescope

According to the BOSS researchers, who presented their work at the 223rd meeting of the American Astronomical Society this week, the findings strongly indicate that the universe is “extraordinarily flat” and that the universe is probably infinite, extending forever in space and time. A flat universe would imply that dark energy, if it exists, is evenly spread throughout the universe, perhaps as a cosmological constant, and does not vary in strength (which would cause curvature). Because we can’t currently “see” faster than the speed of light, it’s hard to say whether the universe is truly infinite or just constantly expanding. Still, an infinite universe would be quite something.


Now read: 9 gigapixels, 84 million stars: Peer into the world’s most detailed photo of the Milky Way


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