Dark energy: the universe is destined to become a very cold and lonely place

Brian Schmidt of the Australian National University in Canberra was recently named as a joint winner of the 2011 Nobel Prize in Physics. The formal citation reads: "For the discovery of the accelerating expansion of the universe through observations of distant supernovae". Prof Schmidt and his team’s work on the expansion of the universe fundamentally changed astrophysics - it opened up a whole new area of science and introduced the world to the concept of dark energy. However, the team was looking for, and expecting, the complete opposite.

“Just like a ball you through up in the air, we expected the universe to crash back down and give us the Big Bang in reverse, which we like to call the Gnab Gib", he says. “But after about 3 years, the data were coming in and it showed that the expansion of the universe was not slowing down at all but was speeding up. That was a real crazy thing to be confronted with. It didn’t make a lot of sense. It seemed just impossible. It was a pretty scary time when we first saw that result.”

Like the recent faster-than-light neutrinos story, the team were faced with a result that must be wrong. After looking for problems with the experiment and checking their results again and again, no mistakes could be found. The team decided to release the data.

“I was expecting a reaction very similar to the faster than light neutrinos announcement. Some people were sceptical, and I don’t blame them for being sceptical. I was sceptical when we released it – I just could not make the result go away. It was just crazy that somehow we had missed 75 per cent of the universe. And this 75 per cent of the universe caused gravity to work in reverse.”

This missing 75 per cent, so-called dark energy, is accelerating the expansion of space. Physicists don’t know what it is – as Prof Schmidt says: “when astronomers discover something they can’t see, they just call it ‘dark x’; in this case x was energy”. The accelerating expansion allows cosmologists to make predictions about the future of the universe.

Prof Schmidt continues: “Right now, when light travels through the cosmos to us it has to compete with the expansion of the universe to get to us. Light takes a long time to get to us, but it gets to us. In the future because the universe is speeding up, it is expanding faster and faster over time, at some point the universe will be so stretched that the light from distant galaxies will never reach us.

“The entire universe that is not gravitationally bound to us right now will eventually be stretched beyond our ability to see it. We will look out to a universe on which you cannot do cosmology because there is nothing to see. It will be a very empty universe.

Read more at The Telegraph