A study of more than 200,000 galaxies, encompassing wavelengths of light from the far ultraviolet to infrared, shows that the universe is producing half as much energy as it did 2 billion years ago and continues to fade.
“Newer galaxies are simply putting out less energy than galaxies did in the past,” astronomer Mehmet Alpaslan, told media reports.
Older stars are fading out faster than new stars are forming, a trend that eventually will leave the universe a cold and lonely place. “At some point, all matter will eventually decay. We’re observing the lights slowly shutting down," Alpasian said.
“The timeline for all this to come to pass is very long, hundreds of trillions of years,” he added.
The study, released at the International Astronomical Union conference in Hawaii, culminates a seven-year, international effort to measure both the distances and energy output of more than 200,000 galaxies.
Seven observatories, including Europe’s Visible and Infrared Survey Telescope for Astronomy (VISTA) and its VLT Survey Telescope, both at the Paranal Observatory in Chile, contributed to the study. Other data came from NASA’s Wide-field Infrared Survey Explorer (WISE) and its now-defunct Galaxy Evolution Explorer (GALEX) space telescopes, and European Space Agency’s retired Herschel space telescope.
“GAMA is the first survey to study a large number of galaxies and map the energy outputs over the range where most of the energy comes out,” lead scientist Simon Driver, with the University of Western Australia, wrote in an email to Discovery News.
Scientists have known since the late 1990s that the universe is slowly fading, but the GAMA study is the first to measure galaxies’ radiation across the spectrum. Measurements were made at 21 wavelengths, ranging from the far ultraviolet to the infrared.
“You’re probing a lot of different kinds of physics when you look at a lot of different energy,” Alpaslan said. “Having the homogeneous data set makes it a lot easier to fully understand what is going on in a galaxy across all these different kinds of physics.”
The decline in galaxies’ energy output coincides with the universe’s ever-increasing rate of expansion, which is due to a mysterious, anti-gravity force referred to as dark energy.