In a bizarre finding that has disrupted the current understanding of the universe, astronomers have detected evidence of a massive gravitational force beyond the horizon of the observable universe. What’s being called a dark flow appears to be pulling vast clusters of galaxies toward a 20-degree-wide patch of sky between the constellations of Centaurus and Vela. “It does fly in the face of everything we know,” said astronomer Dale Kocevski…. “I’m sure it’s going to be controversial” [Discovery News].
When scientists talk about the observable universe, they don’t just mean as far out as the eye, or even the most powerful telescope, can see. In fact there’s a fundamental limit to how much of the universe we could ever observe, no matter how advanced our visual instruments. The universe is thought to have formed about 13.7 billion years ago. So even if light started travelling toward us immediately after the Big Bang, the farthest it could ever get is 13.7 billion light-years in distance. There may be parts of the universe that are farther away (we can’t know how big the whole universe is), but we can’t see farther than light could travel over the entire age of the universe [SPACE.com].
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Ever since researchers first hypothesized the existence of a mysterious force known as dark energy in the mid-1990s, they’ve scrambled for proof that the force exists, and that it is indeed gradually causing the universe’s expansion to accelerate. Now, Hawaiian astronomers say they have found evidence of dark energy’s work by looking at microwave radiation left over from the Big Bang, and how it acts as it traverses strange regions of the universe.
The findings, which will be published in an upcoming issue of Astrophysical Journal Letters [subscription required], focus on regions of space called superclusters, which are dense with galaxies, and supervoids, which are unusually empty of galaxies. “When a microwave enters a supercluster, it gains some gravitational energy and therefore vibrates slightly faster,” [lead researcher Istvan] Szapudi said. As it leaves the supercluster, he said, “it should lose exactly the amount of energy. “But if dark energy causes the universe to stretch out at a faster rate, the supercluster flattens out in the half-billion years it takes the microwave to cross it,” Szapudi said. “Thus, the wave gets to keep some of the energy as it entered the supercluster” [Honolulu Star-Bulletin].
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A new study of a pair of neutron stars has proven that Albert Einstein got the details right on his theory of general relativity, which describes the interactions of gravity, space, and time in our universe. A team of astrophysicists examined two newly discovered neutron stars, the small and dense stellar bodies formed after a supernova collapses, and found that Einstein accurately predicted their movements more than 90 years before the unusual star system was first sighted.
In Einstein’s relativistic universe, matter curves space and slows down time, and the speed of light remains the only constant. But those are the big effects. The theory of relativity also includes some more esoteric details, one of which is called spin precession. The idea goes like this: Two massive bodies orbiting near each other will warp space enough to disturb the central axis around which both are moving, causing them to begin wobbling just like spinning tops. Strong gravity creates this so-called precession, and the more massive the objects, the easier the precession is to observe [ScienceNow Daily News].
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