An international team of astronomers says new data show energy output measured across more than 200,000 galaxies is only about half as strong as it was 2 billion years ago. Scientists point to this latest study as further evidence that the universe is slowly dying.

The Galaxy and Mass Assembly (GAMA) project presented the data at an international astronomical gathering in Hawaii.

"The universe will decline from here on in, sliding gently into old age," said Simon Driver, a professor at the University of Western Australia who also leads the GAMA team. "The universe has basically sat down on the sofa, pulled up a blanket and is about to nod off for an eternal doze," Simon said in the statement.

Scientists have known for about two decades that the universe is fading. Using ground-based and space telescopes, the GAMA study aims to map and model all energy within a large portion of space to get a better understanding of how this is happening.

The GAMA research is the largest-ever multi-wavelength survey and includes energy output at 21 energy wavelengths, from the ultraviolet to the far infrared, according to the group.

What the researchers found is that the decline is seen across all wavelengths.

As NPR's Nell Greenfieldboyce reported for All Things Considered, "that may be because the fuel needed to make stars and keep them going is just running out."

"Once you've burned up all the fuel in the universe, essentially, that's it," says Joe Liske of the University of Hamburg, one of the members of the research team. "The stars die, like a fire dies, and then you have embers left over that then glow but eventually cool down. And the fire just goes out," Liske told NPR.

John Beacom, a physicist and astronomer at Ohio State University, told NPR that before this comprehensive study, there was always the possibility that scientists didn't have the full picture of how the universe was changing. "This pretty much closes the case: Yes, it's coming to an end," he says.

Given that all life depends on energy generation from stars, the universe will become "a bleaker and bleaker place to live," says Beacom. But that doesn't bother him, because death is inevitable — even for the universe.

But don't expend too much energy worrying about it. Scientists expect it to continue for a few billion more years before the final light in the universe goes out.

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