Australian scientists have witnessed the bright flashes of radio waves caused by a cosmic radio burst live for the first time.

The first fast radio burst in space was picked up in 2007 by the CSIRO's Parkes telescope by chance, but this is the first time one has been discovered happening in real time.

Several more radio bursts have been observed in the past few years and scientists have been actively looking into what produces them.

Emily Petroff, a PhD student at the Swinburne University of Technology, was lucky enough to see what no astronomer has ever seen before.

"It was really exciting, it was something we had been waiting for for a while," Ms Petroff said.

"We set up a real time system in March last year, and we had been hoping for a while that we would find one. So to have one pop up while we were observing was just really exciting."

A fast radio burst is a quick flash of radio waves that lasts just milliseconds. Even though it was just observed here on Earth, it happened a long time ago in space.

"The universe is 13 billion years old and we are looking from present day. But the further and further away from us we look, we are looking at light that was emitted longer and longer ago," Ms Petroff explained.

"So when we're seeing these fast radio bursts, we think that they're coming from very far away, so billions of light years away.

"The light we're seeing from them is from a time when the universe was much younger."

Bursts possibly caused by star collapsing: Johnston

It is not known exactly what causes cosmic radio bursts, but Dr Simon Johnston, the head of astrophysics at the CSIRO, has theories.

"One of the front runners is a neutron star collapsing to form a black hole. And that's a very exciting possibility," he said.

"If we can see that happening, it gives off a big flash of radio waves from the far distant universe, and that's really very exciting."

Dr Johnston said astronomers and cosmologists were interested in learning both what causes the bursts and how the radio waves travel through space.

"We don't know what [the cause] is and so that's always interesting to find out," he said.

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"But the other interesting thing is how do the radio waves go from the source, which is maybe five billion light years away. How does it travel from there to our telescope?

"Knowing how it travels and what it goes through is also very exciting for the cosmologists, because we really don't know what the stuff is like in between the galaxies. This fast radio burst allows us to probe that."

Professor Bryan Gaensler, the director of the Dunlap Institute for Astronomy and Astrophysics at the University of Toronto, agrees learning more about the phenomenon could teach us more about the universe.

"What's really exciting is the signal has travelled from one side of the universe to the other, and as it does so, it encodes information about all the matter in between us," Professor Gaensler said.

"So what scientists would really like to do is take the whole universe and put it in a giant sack, and put it on a set of scales and weigh the universe.

"Obviously, that's not something that we can do practically, but by counting up the amount of stuff that these signals travel through — as they go from wherever they begin, to Earth — you can actually quite precisely weigh the universe.

"And that will answer some really profound questions about just what the universe is made of, how it began, and what most of the invisible gas out there actually is."