Ever-expanding universe nets top prize
Scientists who discovered the fingerprint of mysterious dark energy in the form of an ever-expanding universe have been honoured with a top science prize.
Two international teams of scientists share the US$500,000 Gruber Cosmology Prize for their discovery, which radically changed our model of the universe.
"An accelerating universe was a crazy result that was hard to accept," the Gruber Foundation said in announcing the prize.
Astronomers used to assume the universe would slowly stop expanding because they thought the pull of gravitational attraction would act like a brake.
It was this assumption that triggered Schmidt team's use of universal expansion to calculate how much matter there was in the universe.
The researchers used the movement of distant supernovae to track the expected slowdown in expansion, with the aim of then deducing out how much matter there was.
But instead the researchers found expansion had been accelerating over the past 5 or 6 billion years.
The observations pointed to an idea that Albert Einstein first proposed in 1917, that there was some form of energy - now known as dark energy - that was tied to space itself and would repulse itself under the effect of gravity.
Support for 'a fringe idea'
Schmidt says this theory was considered to be very much "a fringe idea" at the time his team made the first direct observation of its effects, so the discovery was unsettling.
He says they checked and checked again to make sure they had not made a mistake.
"But I was still scared that somehow we had just missed something," Schmidt says.
And it wasn't helped when at one stage he thought the rival team had found the exact opposite.
But after years of neck and neck competition both teams announced the same finding.
Dark energy is now estimated to make up 72% of the universe's density with conventional matter making up just 4%, says Schmidt.
The rest is dark matter, which can't be seen directly but which has gravitational effects on visible matter.
Connecting forces of nature
Schmidt says he is now trying to observe dark energy in more detail.
"We're trying to track very accurately its behaviour back in time and see if it really is tied exactly to space, as Einstein would have suggested, or whether or not it varies a little back in time."
Schmidt says understanding dark energy could help physicists combine the theory of quantum mechanics (the theory of the very small) with the theory of gravity (the theory of the very large).
"People are hoping that this dark energy is some sort of manifestation of the interplay between gravity and quantum mechanics," he says.
"Tying down what this dark energy is we could solve one of physic's greatest troubles: how to join all the forces of nature into one story."
20 billion years left for cosmology
If the universe does continue to expand into infinity, distant supernovae will be harder to see, which has implications for cosmologists like Schmidt, who rely on these as reliable light sources to study dark energy.
But there's a little time left before he's out of a job.
"I would say cosmology will remain doable for at least the next 20 billion years," says Schmidt.