ROBERT SIEGEL, HOST:
One law of the universe is that all that begins must come to an end. Well, astronomers say that this is just as true for the universe itself, which began 14 billion years ago with the Big Bang. Researchers at a scientific conference today presented new evidence that the universe is slowly dying. NPR's Nell Greenfieldboyce reports.
NELL GREENFIELDBOYCE, BYLINE: Astronomers have long contemplated the end of the universe.
ANDREW HOPKINS: When will it end? How will it end? Will it just go on forever?
GREENFIELDBOYCE: Andrew Hopkins is at the Australian Astronomical Observatory. He says research in recent decades has produced a preview of the future, and it's kind of grim.
HOPKINS: The universe will continue to expand at an ever-accelerating rate until it goes out with a whimper, if you like - the opposite of the Big Bang.
GREENFIELDBOYCE: As everything gets farther and farther apart, the universe will become desolate and barren. What's more, astronomers can also see evidence that the rate at which galaxies form new stars has been declining.
HOPKINS: And it's been declining progressively for the last half or more of the age of the universe.
GREENFIELDBOYCE: Hopkins and a bunch of other researchers wanted to make the best measurements yet of how the universe is fading. They used an assortment of space and ground telescopes to look at the energy output of over 200,000 galaxies, looking at 21 different wavelengths, from the ultraviolet to the far infrared. They presented their findings today at a meeting of the International Astronomical Union in Hawaii.
HOPKINS: We've been able to show that the energy production of, say, 3 billion years ago was substantially higher than the energy production in galaxies in much more recent times.
GREENFIELDBOYCE: That may be because the fuel needed to make stars and keep them going is just running out. Joe Liske is on the research team. He's from the University of Hamburg in Germany.
JOE LISKE: Once you've burned up all the fuel in the universe, essentially, that's it. Then, you know, the stars die like a fire dies. And then, you know, you have embers left over that then glow but eventually cool down, and the fire just goes out.
GREENFIELDBOYCE: He says the universe's slow decline will continue for a long time, maybe tens of billions of years. John Beacom is a physicist at Ohio State University. He said, before this comprehensive study, there was always the possibility that scientists didn't fully understand how the universe was changing.
JOHN BEACOM: This pretty much closes the case. Yes, it's coming to an end.
GREENFIELDBOYCE: He says all life depends on energy generation from stars.
BEACOM: And if that disappears, it becomes a bleaker and bleaker place to live.
GREENFIELDBOYCE: So it's a pretty ugly picture. I mean, (laughter) do you find this depressing, or is it all so far off in the future that you just don't even worry about it?
BEACOM: It doesn't bother me at all.
GREENFIELDBOYCE: He's says death is inevitable, even for the universe. Nell Greenfieldboyce, NPR News. Transcript provided by NPR, Copyright NPR.
