Waves of joy: why astronomers are ecstatic about colliding neutron stars


Witnessing the collision of a pair of neutron stars was the biggest science event of 2017. Lauren Fuge reflects on why astronomers are so excited.


An artist’s impression of colliding neutron stars
An artist’s impression of colliding neutron stars
MARK GARLICK/UNIVERSITY OF WARWICK

Every few years, a discovery is announced that makes scientists so excited they could explode – consider the rockstar coverage that greeted the discovery of the Higgs boson in 2012, or the triumphant global cheer when Curiosity landed safely on Mars in the same year.

On 16 October 2017 the announcement of another science spectacle swept the world: for the first time, astronomers had been treated to the cosmic fireworks of colliding neutron stars. They could both listen – thanks to gravitational waves – and watch – thanks to electromagnetic waves. Astronomers the world over were catapulted into a frenzy. Here are five reasons why.


1. Their life’s work was just validated.

The reality of science – and especially physics and astronomy – is that, sometimes, scientists end up studying phenomena that they’re not 100% sure actually exist. For some researchers, this discovery confirmed that they haven’t wasted their careers.

Anna Heffernan, Marie Curie Fellow at the University of Florida and the University College Dublin, summed up the sentiment: “I’ve spent my life looking at gravitational waves – at least, the last 11 or 12 years – and to actually find that they really do exist and I haven’t dedicated 12 years to nonsense was a very good feeling.”

David Blair, from the University of Western Australia, spent even longer in the dark. “I started working on the first high sensitivity gravitational wave detectors in the USA in 1973,” he said. “I expected to spend a year or two detecting Einstein’s waves and then move on to something else ... Forty-four years later we have found the holy grail!”


2. Astronomers have reached a goal they have chased for decades.

This discovery not only validated many scientists’ entire careers but also marked the triumphant achievement of a long-held and dearly desired goal: “That is,” said National Science Foundation director France Córdova, “to simultaneously observe rare cosmic events using both traditional as well as gravitational-wave observatories.”

It is “very, very exciting” that it worked out in the end, said Rainer Weiss, LIGO co-founder and winner of the 2017 Nobel Prize in Physics: “For as long as 40 years, people have been thinking about this, trying to make a detection, sometimes failing in the early days, and then slowly but surely getting the technology together to be able to do it.”

Scientists persisted for so long, explained Tamara Davis from the ARC Centre of Excellence for All-Sky Astrophysics (CAASTRO) and the University of Queensland, because hearing this faint sound and momentary burst of light confirmed a suite of predictions – “such as how the heavy elements were created, what happens when neutron stars collide, and how fast is the universe expanding.”

Ju Li, of the University of Western Australia, agreed: “It is extraordinary that with one faint sound, the faintest sound ever detected, we have created one giant leap in our understanding of the universe.”

Blair adds: “This is the most amazing vindication of all of Einstein's theories.”


3. The discovery involved a massive, unprecedented global collaboration.

After the initial gravitational waves alert on August 17, hundreds of astronomers around the world leapt into action to try and spot electromagnetic radiation from the source.

Stefano Covino, at INAF–Osservatorio Astronomico di Brera in Italy, says the effort was frankly impressive. “The days were filled with frenetic and exciting activity,” he remembers. “You had the precise feeling that something historic was happening.”

According to Dave Reitze, executive director of LIGO, these mass-scale follow-up observations allowed astronomers to obtain “a full picture of one of the most violent, cataclysmic events in the universe. This is the most intense observational campaign there has ever been.”

Matthew Bailes, the Director of the ARC Centre of Excellence for Gravitational Wave Discovery, agrees that the “avalanche of science was virtually unparalleled in modern astrophysics.”

As a result, dozens of research papers went online on October 16, the day of the official announcement. One paper in particular demonstrates the mind-blowing scale of the collaboration – it’s co-authored by almost 4000 astronomers from more than 900 institutions: about a third of all astronomers in the world.


4. It marks the beginning of a new era of multi-messenger astronomy.

“Probably the most exciting thing of all is really that it's the beginning,” says Richard O'Shaughnessy at the Rochester Institute of Technology's Center for Computational Relativity and Gravitation. “This is a transformation in the way that we're going to do astronomy.”

His sentiment was echoed by almost every astronomers who spoke about the event. If there’s one thing scientists get universally excited about, it’s doing more science.

Jeff Cooke from Swinburne University is among the enthusiastic horde: “Before this event, it was like we were sitting in an IMAX theatre with blindfolds on. The gravitational wave detectors let us ‘hear’ the movies of black hole collisions, but we couldn't see anything. This event lifted the blindfolds and, wow, what an amazing show!”

Neil Tanvir from Leicester University explains further: “This discovery has opened up a new approach to astronomical research, where we combine information from both electromagnetic light and from gravitational waves. We call this multi-messenger astronomy – but until now it has just been a dream.”

Some astronomers, like Edward van den Heuvel from the University of Amsterdam, are already getting pumped for what the next few decades hold.

“Within 20 years or so, gravitational-wave measurements may be just as routine as X-ray observations have become over the past 40 years,” he says. “It’s really beyond my wildest dreams.”


5. It’s just plain cool.

There’s just no getting around the fact that measuring miniscule fluctuations in the fabric of spacetime from a titanic clash of ultra-dense stars 130 million years ago – and in the process, finding that our predictions were spot on – is just amazingly cool.

Covino is particularly excited because the data coming in so far “are an amazingly close match to theory. It is a triumph for the theorists, a confirmation that the LIGO–VIRGO events are absolutely real.”

Stephen Smartt of Queen’s University Belfast agrees wholeheartedly: “It’s quite amazing that these physical models predated the discovery by years, but ended up being very similar to the data that we actually saw!”

According to David Coward from the University of Western Australia, he and his team “knew on day one, when the event happened, that this was something big. This is like gold for scientists.”

For some astronomers, the discovery is so awesome that words just aren’t enough.

"Superlatives fail,” says O'Shaughnessy.

Lauren Fuge is an Adelaide-based author and science communicator.
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