Waterloo researchers help create largest 3D map of universe
International researchers worked to help fill gaps in knowledge about the universe
A University of Waterloo astrophysicist has led a team of international researchers to create the largest ever three-dimensional map of the universe.
Will Percival says the map fills in gaps in knowledge about the universe and "it's like a gold mine of information about the universe."
The galaxies are not positioned randomly like darts on a dartboard, he said. Instead, they cluster and there are voids where there are no galaxies.
"This pattern of the galaxies encodes a lot of information about the physics that's going on in the universe," he said.
Percival, who is an associate faculty member at the Perimeter Institute in Waterloo and also the director of the Waterloo Centre for Astrophysics at the University of Waterloo, says a two-dimensional map is a bit easier to create. To do so, a scientist looks at the night sky to see where the galaxies are and measure the angular positions.
"But to get the radial information is very difficult and to do that we get the spectra from each galaxy, that's the colour of each galaxy, and then we work out how fast it's moving away from us, and we actually used the expansion of the universe itself to tell us the distance. And then we've got the three distance measures that give us a three-dimensional map," he said.
Listen to Will Percival's inteview on CBC's The Morning Edition
'It seemed like magic'
The map shows there's a preferential scale for the distance between galaxies. That scale is fixed and expands with expansion of the universe, so it can be used like a "standard ruler."
The preferential scale has led to one of the most exciting results, Percival said. Looking at present day, researchers now know the universe's expansion is accelerating.
He noted with standard gravity, Albert Einstein's theory of general relativity, the universe's expansion would expect to be slowing down.
"But we're seeing it's accelerating. We don't know why. This is new physics. We call it dark energy. We don't know what it actually is. We have a name for it, we don't actually have a mechanism," he said.
"That's really exciting," he said, likening the finding to when electricity was discovered.
"When that came about it seemed like magic. People, when they don't understand the physics, they call it magic," he said. "Eventually, you work out the mechanisms, you work out what's happening."
At the moment, he said, "we're in the discovery phase. We know there's something out there, we know there's an anomaly, we don't understand it, we have yet to figure out exactly what it is."
Watch the CBC's The National report about the new 3D map:
Map available to all
The map is part of the Baryon Oscillation Spectroscopic Survey (eBOSS), an international collaboration of more than 100 astrophysicists. The eBOSS is part of the Sloan Digital Sky Survey, a 20-year research project looking at cosmic history.
Dustin Lang, a computational scientist at The Perimeter Institute in Waterloo and who helped to put together the data, said in a release that the work of that 20-year study and this new map provide "significant legacy value" for those who study the skies.
"It really is incredible that one experiment has produced such a scientific legacy."
Work on the map will continue going forward, Percival said. He says there are experiments starting that will do more maps with more galaxies, which will cover a "denser" sampling of the galaxies.
"They're going to try to beat down the noise and really increase the information we have on dark energy even more," he said.
The map has been made available for anyone from scientists to people just interested in learning more, to use. It can be found on the Sloan Digital Sky Survey website.
Percival says this will allow more people to download the map, analyze it and measure things about the galaxies and the universe that "we never even thought of doing." This, he says, will only add information to the ongoing research into the universe.
Watch a University of Waterloo video on the research: