How Does Dark Energy Stretch Our Universe?
Scientists have just mapped 1.2 million galaxies! Here's how this 3D map can be used to learn about dark energy and dark matter.
Heads up, mapmakers. Researchers with the Sloan Digital Sky Survey have just completed what may be the single most ambitious project in the history of cartography. Ian O'Neill has the details in today's interstellar DNews report.
After more than a decade of work, scientists have created a 3-D map of an entire region of the universe -- tracking 1.2 million galaxies covering a quarter of the visible sky. The total area mapped is around 650 billion cubic light years.
The new measurements were carried out by the Baryon Oscillation Spectroscopic Survey (BOSS) program, with the goal of better understanding the strange effects of dark energy. More specifically, the map helps explain the cosmic push-and-pull between dark energy and dark matter, which cosmologists believe dictates the very shape and evolution of the universe.
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It gets complicated, but here goes: It's believed that dark energy makes up 70 percent of all the energy in the universe, and has a bizarre anti-gravity effect on space-time. To really understand how it works, we need to look at a big swath of sky and track changes over a vast amount of time.
As such, the new map actually looks at those 1.2 million galaxies as they existed between two and seven billion years ago. This is the time when, it's theorized, dark energy took charge in the universe and caused vast galactic clusters to fly away from one another. By analyzing the distance between these clusters, we can see how fast the universe expanded under the force of dark energy.
One extremely cool revelation has already come out of the project. It appears that the universe is expanding in precisely the way we theorized, with dark energy continually stretching space-time while dark matter tries to pull it all back in again. This suggests that general relativity holds up at ginormous cosmological scales. In other words, Einstein was right. As usual.
Check out Ian's report for more details -- he's our space science producer and is impossibly good at explaining these things.
Astronomy: BOSS Makes The Most Precise Measurement Yet Of The Universe's Expansion
NASA: Dark Energy, Dark Matter
Harvard: Baryon Acoustic Oscillations