Washington, August 6 : Astronomers at the University of Hawaii have observed what may be the clearest detection of dark energy to date, by looking at microwaves left over from the beginning of the universe some 13.7 billion years ago.
According to a report in Discovery News, the scientists grouped the rays depending on whether they had passed through massive clusters of galaxies or bee-lined to Earthly detectors through areas largely lacking galactic real estate.
The premise was that these "background" microwaves would pick up a little energy as they entered the clusters, urged on by the forces of gravity.
But if gravity had a monopoly on the game, the rays would lose that snap as they pressed through the other side, rendering the energy gain a transitory phenomenon.
As to how the microwaves passing through super-sized galaxy clusters got to keep a bit of unearned gain, Istvan Szapudi and colleagues from the University of Hawaii believe it is because dark energy, which sometimes is referred to as anti-gravity or vacuum energy, had spread out the galaxy clusters, as it is doing to all space. y the time the microwaves exited, there was proportionally a bit less mass to deal with, leaving the rays with a slight energy advantage.
"It's kind of like if you have a car on a hill. You pick up energy as you're going down, but you give it all back up again when you go up," explained Gary Hinshaw of NASA's Goddard Space Flight Center in Greenbelt, Maryland.
"What is happening here is that the acceleration of the universe is forcing the gravity wells to be less strong. So over the time it takes for energy to cross the cluster, the strength of the cluster has diminished," he added.
The measurements are difficult to make because tiny variations in the Big Bang remnant waves are larger than the observable effects of intervening galaxy clusters and voids.
But, by grouping together data from background radiation maps of the 50 largest galaxy clusters and the 50 largest voids, researchers were able to come up with a finding they say has only a one in 200,000 chance of being a statistical fluke.
The data was taken from Sloan Digital Sky Survey, which has mapped the distribution of galaxies in about 25 percent of the sky.