For decades, astronomers around the world have observed dozens of pulsars; These super-dense remnants of exploded stars emit regular pulses of radio waves and spin at ridiculous speeds like out-of-control lanterns. Last week, dozens of physicists began promising to make public the results of these observations, which could eventually change our understanding of the universe.

On the evening of June 28, several research teams announced that they had found evidence of low-frequency gravitational waves: extraordinarily long waves in the fabric of space-time that only slightly changed the timing of pulsars’ pulsating signals. In further research, the pulsar network could act as a galactic-scale telescope to see the sources of these waves, potentially providing clues about the evolution of millions of galaxies in the universe.

“Studying the origin of these gravitational waves can help us tell the story of how galaxies are born, how they grow, and how they die,” said Roger Blandford of Stanford University, who answered some questions about the significance of the announcement to Stanford News.

This announcement is the culmination of years of data collection from pulsars in our Milky Way neighborhood. What distinguishes these findings from previous ones?

The signal these astrophysicists were looking for was announced a few years ago, but they failed to confirm the signature of low-frequency gravitational waves rather than a general signal. They are now beginning to see for themselves the characteristic signatures of gravitational waves. There’s still some doubt, there should be, but I think it’s a pretty accurate measurement.

Where could these gravitational waves come from, according to astrophysicists?

What they’re looking at is a background of gravitational radiation from many undifferentiated sources – like looking through a fog, for example, seeing diffused light instead of a single source. However, as their sensitivity increases, they should begin to see the individual sources nearby that make up the background nebula. How long it will take to get to this point depends on how advanced pulsar observation techniques are and what gravitational radiation sources actually exist. The leading candidate for the source of what they have now identified is a population of merging massive black holes.

What is important in the study of the origin of gravitational waves?

This can tell us a lot about the life history of galaxies. A big part of that is how they come together.

The main interpretation is that a long time ago, smaller galaxies merged into larger galaxies, and the black holes at the centers of these galaxies also merged. But we don’t have conclusive evidence that black holes merge or how, because if you really look for these double black holes, they’re pretty shy. So if the idea that these gravitational waves are caused by the merging of black holes is confirmed by more observations – and it’s certainly on the right track – then we’ll have an important piece of the story on how galaxies merged. It’s more like paleontology or archeology than doing physical experiments.

What do you think is the most important thing people need to understand about the scientific process involved in a discovery of this magnitude?

This is collaboration. Expert in signal processing, expert in using telescopes, etc. there are people. And it’s an international initiative: There’s NANOGrav in the US that observes pulsars, but there are five other teams there. They will try to combine their signals to get a stronger result, and it will get even better in the future as they observe more pulsars over longer periods of time. They all need to compete, cooperate and collaborate. It is difficult! And all this comes with a price to pay – thanks to the National Science Foundation for driving this research for 15 years. This is a lot of work and I would be very surprised if it had a major downside. It looks like we’re opening a new window to the universe. Source