The universe is going to become a cold and boring place in a few billion years. New research suggests it is expanding at an accelerating rate that, in time, will allow the stars to go out and all warmth to disappear.
This bleak but distant cosmic endgame was outlined last night in Dublin at a lecture by the director of the Hubble space telescope, Prof Steve Beckwith. He delivered his keynote address during the UK National Astronomy Meeting, taking place this week at Dublin Castle.
Images from the Hubble have helped in many cosmological discoveries since it went into service in 1990, and Prof Beckwith illustrated his presentation with some of the most striking images taken by the Hubble. His talk was organised by the Royal Irish academy and The Irish Times, with the support of DEPFA Bank.
Prof Beckwith said he would deal with two key themes during his talk: the Hubble's ability to show us how stars and planets form, and its potential to take us back in time towards the origins of the universe. The telescope gives us "a sense of how the cosmos evolved with time", he said, with infant, adolescent and adult stars all on display.
"When we look out into the universe we can watch the life cycle of stars and the birth of planetary systems," he said. "The Hubble telescope has been an essential tool in revealing that in a way we have never been able to before."
The telescope's ability to pick out extremely distant objects also allowed us to travel back in time. "Because the light reaching us travels at a finite speed, as you look out to more distant things you are actually looking back in time," he stated. "The universe is also a finite age. It is about 13 billion years old. With the Hubble we can now see back to a time when the universe was only one billion years old or less."
In the same way that astronomers can view the evolution of a star using Hubble images, they can view the evolution of the universe itself as it expands from the moment of the Big Bang.
"The oddest but probably one of the profoundest discoveries of recent years is the expanding universe," he said. Hubble images have shown how cosmic expansion has evolved over time, with a slower expansion at the beginning giving way to a faster expansion.
Researchers believe they understand the Big Bang but not what might be driving this accelerated expansion. "There is apparently another energy field out there. We call it dark energy and it acts like antigravity," he said. It will spread out matter further afield over time, turning the universe into "a cold and rather unpleasant place" in the future. "You can see how you are confronted with certain philosophical challenges."