Researchers presented their findings on Monday at the International Astronomical Union XXIX General Assembly. The survey, which is part of the Galaxy and Mass Assembly (GAMA) project, used several powerful telescopes to measure the energy output of some 200,000 galaxies, some far enough away to give us a glimpse into the past -- because of how long it takes the light from those stars to reach our telescopes.
Based on observations of the galaxies over 21 different wavelengths of light, which allowed researchers to calculate their energy output, their rate of star formation and the rate at which they merged with one another, astronomers have concluded that the universe is dimming. Just 2 billion years ago, they report, the energy being produced in the section of the universe they studied was twice what it is today.
“The universe is curling up on the sofa and becoming a couch potato,” study author Joe Liske of the European Southern Observatory told the Guardian.
Scientists already knew that the stars of the universe were getting less bright in terms of ultraviolet light. However, this is the first study to look across all wavelengths of light, showing the general trend toward darkness and nothingness.
Here's what's happening, in a nutshell: The universe reached its peak period of star formation a long, long time ago. There just isn't as much raw material to work with as there used to be. The laws of physics are such that usable energy will increasingly waste away into forms that stars can't use, like heat.
It's not as if a "dead" universe would disappear. But with fewer and fewer bright stars, there would be fewer and fewer opportunities for life to evolve and thrive. One day our universe will host only dimly-lit stars, and those will dwindle over time, as well.
But don't be too depressed: The sun is going to burn out way before we have to worry about the universe itself running out of energy.
"It’s going to be a long process; I guess we've got worse things to worry about at some level,” lead researcher Simon Driver of the University of Western Australia told the Los Angeles Times. “In about 5 billion years the sun is going to swell up and swallow the Earth; in about 10 billion years it’s going to collide with the nearest [major] galaxy, the Andromeda galaxy; and in about 100 billion years the universe will be so expanded and producing so little light that we basically won’t see anything."
So that's comforting.