Physics and political science senior David Narkevic had been looking through readouts of radio signals from the Parkes Radio Telescope in Australia. He was looking for more examples of a kind of rotating star—a pulsar—that emits very short radio signals. And he found something.
It was strange. A dark line in a place on the graph that meant it was incredibly far away. If the reading was right, it was possible that the signal was both a billion light years away and a billion years in the past.
Lorimer took a look. And then he put it aside. It probably wasn’t anything. “I kind of told him to go back to work, and I put it in a drawer,” Lorimer said.
“Are these mystery radio bursts messages from ALIENS?” – DAILY MAIL, U.K.
But over the next months, his internal dialogue changed. It could be interference. But it wasn’t. It was in the wrong place for that. It could be a pulsar. It was short after all. But it didn’t repeat. The spinning of pulsars—on which his bread and butter is founded—is more regular than any timing mechanism on earth. Then Lorimer and colleagues visualized the data in a different way, which revealed a bright signal that looked very likely to originate from deep in the cosmos. And it was clear this had to be shared with the scientific community.
“At one point there were more theories than gamma-ray bursts.” – DUNCAN LORIMER, ASTROPHYSICIST
In the title of the paper Lorimer, Narkevic and others published in Science later that year, they called it “a bright millisecond radio burst of extragalactic origin.” They suggested that others of these invisible radio signals could be appearing hundreds of times each day. Scientists and journalists took to calling their find the Lorimer burst.
Because for the next five years it was the only one. And when someone found another in 2012, it seemed much closer to home in the Milky Way. A few others were put forward, but they were cast aside as solely radio interference.
“It was speculated that the original event was one of those,” Lorimer said. “So a lot of people were beginning to close the file and move on to other things.”
But in 2013, four more were found. And that opened the starting gates. More astronomers started looking in earnest. Lorimer got his first funding to continue his own search. And the signals got a name. They were called fast radio bursts.
It was a nod to their brevity and to the decades-long search for gamma-ray bursts that kicked off in the ’60s when spy satellites picked up gamma energy from what we now know is likely to be due to explosions of massive stars and collisions of neutron stars at great distances.
But there was still one more noticeable problem. Every signal that had been found so far had only been found with records from that one telescope. Until this year.
A group of scientists discovered more signals using the Arecibo Telescope in Puerto Rico. And the idea that would surface that this signal was somehow related to the Parkes Telescope was quashed for good.
Scientists believe now that there could be 10,000 of these radio signals appearing every day. Lorimer says to picture a sky filled with fireflies. If one flashed every 10 seconds, that’s what we would see—if we could see radio waves.
We know them to be real now. But what they are has become the guess of about 100 scientists and many more people of other persuasions.
“Are these mystery radio bursts messages from ALIENS?” the Daily Mail in Lorimer’s native U.K. proclaimed this spring. The list of possibilities is extensive. For example, they could be due to pairs of neutron stars colliding, as is thought to be the case for some gamma-ray bursts. And they could be things that have never been proven to exist. One possibility involves kinks in so-called “cosmic strings,” which are hypothesized to be large-scale deviations in the structure of spacetime. Another idea is that the bursts represent a last gasp from the evaporation of black holes that were formed at the beginning of the universe.
It’s also possible that they’re much more humble, such as energy releasing from solar flares, Lorimer says.
“At one point there were more theories than gamma-ray bursts, and that’s kind of where we’re at now,” he said of the fast radio bursts. “But it’s fun because your imagination can just run riot until there are more observations to constrain it.”
For this research to advance, scientists need more finds and lots of them. Lorimer and researchers at the University of California at Berkeley and the University of Oxford installed a detector this summer to collect data from Arecibo.
And Lorimer is also on board a project to search for the bursts at the National Radio Astronomy Observatory in Green Bank, W.Va.
Lorimer estimates that in the next five years we’ll know what the bursts are and how to use them in exploring space.
“Your imagination can just run riot until there are more observations to constrain it.” – DUNCAN LORIMER
“It could turn out that they’re really rather mundane, and we might not be using them for very much,” Lorimer says with a wry laugh. “Right now it’s an interesting race just to figure out what they are and worry about it after that.”
He realizes we may never know exactly what that first signal was telling us. We know that something happened a billion years ago in the universe. And we know that a student walked into a professor’s office with a piece of paper.
And a message was delivered.