US theoretical physicist Dr Brian Greene says we're in a "new era" of astronomy. Photo / Supplied
US theoretical physicist Dr Brian Greene says we're in a "new era" of astronomy. Photo / Supplied
One of the world's best-known scientists says a game-changing discovery about our universe has ushered in a new age of astronomy and he credits a Kiwi for a pioneering part in it.
US theoretical physicist Dr Brian Greene, who gives a public talk at Auckland's Bruce Mason Theatre this Sunday, said the 2015 discovery of what are called "gravitational waves" has sent ripples through the world of science, much like the waves themselves are ripples that flow through the universe at the speed of light.
The waves, which are comparable to sound waves, had been assumed to exist by scientists since Albert Einstein proposed more than a century ago that space-time, which makes up our universe, was a four-dimensional fabric that can be pushed or pulled as objects move through it.
But when a team of physicists from the US-based Laser Interferometer Gravitational-Wave Observatory (Ligo) confirmed their existence by capturing them, it allowed scientists to understand how the universe works in an entirely new way, just as we could observe the surface of a pond stirred by ripples.
It meant being able to observe colliding black holes, merging neutron stars, or gargantuan collisions of galaxies.
Where ripples had been made, we could trace them back to the event that created them.
Because waves were neither scattered nor absorbed by the material they pass through, like the pond surface, they let us peer right into the heart of some of the most extreme environments in the universe, such as black holes and neutron stars.
Humans could now conduct fundamental physics experiments under conditions that could never be copied in a lab on Earth.
"I think it was a huge game-changer, in the most straight-forward of ways," said Greene, who is chairing a panel discussion on gravitational waves at the World Science Festival, held in Brisbane this week.
"For thousands of years, we have examined the universe in only one way, using waves of light, and now for the first time we can examine it using waves of gravity.
"In the next 20 years, I can't imagine that we won't discover something completely unexpected using these waves."
Greene paid tribute to Emeritus Professor Roy Kerr, the New Zealand scientist whose theory is widely known in physics as the Kerr vacuum, and who last year received one of international science's most coveted honours, the million-dollar Craaford Prize.
In the 1960s, Kerr was credited with finding the solution of Einstein's equations which describes rotating black holes.
The Ligo team concluded that the waves it discovered were produced during the final fraction of a second of the merger of two black holes to produce a single, more massive spinning black hole.
Greene said Kerr's foundation-laying contribution to the ultimate breakthrough was "huge".
"His work was a vital step toward understanding the most general kind of black hole that there might be," he said.
"And it was a mathematical tour de force. The solution that he found was so hugely influential."
Two merging black holes create rippling gravitational waves. Photo / 123RF
Greene said he believed the discovery, observed in September 2015 and announced in February 2016, would prove a pivotal moment in history.
"There are a handful of moments where you think there's been a radical shift in our capacity to examine the universe and this is one of them.
"September 14, 2015, will be remembered as one of those moments; it was like discovering a new kind of telescope."
• Dr Brian Greene will present his show A Time Traveller's Tale at Auckland's Bruce Mason Centre at 7.30pm on Sunday, March 26. Tickets are available through Ticketmaster
Earth 2.0: Could we colonise another planet?
Could there be other Earth-like planets out there that could make humanity's new home? Photo / 123RF
Jumping ship from our planet to another has long been the stuff of science fiction but the concept is one talking point at this week's World Science Festival in Brisbane.
It comes after the recent discovery of Proxima b, an exoplanet orbiting within the habitable zone of the closest star to the sun, and which raised the exciting prospect of Earth-like planets hanging about in our corner of the galaxy.
Late last year, famed theoretical physicist Professor Sir Stephen Hawking even gave humanity a deadline to find a new home: 1000 years.
Scientist and Mars Society Australia president Dr Jon Clarke said while the possibility of colonising another planet still seemed remote, we were now aware that other planetary systems exist and were "really common, making this more of something that we might actually do some day".
As for what planet might make a suitable candidate, Clarke said, the more Earth-like it was, the better.
That meant a similar gravity and light levels, reasonable atmospheric pressure, conditions that weren't too toxic and a comparable rotation in orbit.
What hurdles might mankind be able to overcome and adapt to?
"This is the hard to say as we don't know the limits of human adaptability," said Clarke, who is taking part in a panel discussion on the topic.
"In some cases it might be easier to live on an airless body such as the Moon with abundant resources in the form of ices, than on a more Earth-like body with abundant toxic dust, like asbestos, or excessive radioactivity.
"We also need to consider that research stations might be set up on environments that externally are quite hostile, but people would be living in comfortable enclosed habitats."
While Clarke thought it possible that we'd discover Earth-like planets within decades, getting to them would still take centuries, barring the development of unforeseen technology.
Closer to home, Clarke considered manned Mars expeditions, something former US President Barack Obama called for by the 2030s, were within our grasp, and might involve stations similar to that in Antarctica.
"Mars settlements may be possible, if we can show that people can live healthy and productive lives over successive generations.
"Mars may have its extremes, but remember that people will live in enclosed environments that won't be like that.
"They would be quite comfortable places to live in."
Despite Hawking's comments, Clarke said he believed that, with care, our own planet would remain habitable for tens of millions of years, "so there is no urgency in this regard".
"Will there even be humans about in 20 million years? Probably not.
"But ultimately having human civilisations spread across the solar system, and several, will reduce the possibility of catastrophes wiping them out.
"But we do need to remember that no civilisation, no species, can be expected to last forever."
• Jamie Morton was hosted at the World Science Festival by Brisbane Marketing.
