STEM: Wave of Scottish discovery sheds new light on mysteries of the universe

First predicted a century ago by Albert Einstein, the existence of gravitational waves has been confirmed, with physicists at the University of Glasgow making a major contribution to their discovery.

Their work has included the development and fabrication of the delicate mirror suspensions which make the detections possible and the data analysis which sorts the gravitational wave signals from the background noise of the universe. 

Gravitational waves carry unique information about the universe’s origins and studying them provides important insights into black holes, supernovae, gamma-ray bursts, and neutron stars. Even for colossal cosmic events such as the collision of two black holes, the fluctuations in spacetime are tiny by the time they arrive at Earth.

The longest-serving member of the University’s gravitational research community is Professor James Hough, who has worked in the field at the University since 1971. 

“Alongside Professor Ronald Drever, I was involved in building early gravitational wave detectors here in Glasgow, which monitored outputs from piezoelectric transducers attached to aluminium bars," he said.

"We thought it would take us about a year to make an initial detection and in 1972 we found what looked very much like evidence of gravitational waves.

“However, since no other detectors were operating at the same time, we weren’t able to verify our observation. Nonetheless, that finding convinced me that we would one day find the evidence we were looking for.

“The discovery, 43 years later, is the culmination of my career in science. I’m immensely proud to have been involved in the project and I’m very excited to see the fascinating new discoveries gravitational wave astronomy will bring us in the future.”

Gravitational waves require incredibly sensitive equipment to be detected, using a technique called laser interferometry, and were directly detected for the first time in September 2015 by the ground-based Laser Interferometer Gravitational-Wave Observatory (LIGO).

Alongside their success in the LIGO detection, Glasgow scientists are playing a crucial role in the development of a space-based gravitational wave observatory as not all cosmic events that produce gravitational waves can be sensed by ground-based detectors. An observatory in space also has the bonus of being free of the seismic, thermal and terrestrial gravity noises that limit ground-based detectors.

LISA Pathfinder was launched on December 3, 2015, reaching its operational orbit roughly 1.5 million km from Earth towards the Sun in late January 2016.

Scientists at the University of Glasgow developed, built, and tested the incredibly sensitive optical bench interferometer that lies at the heart of the LISA Pathfinder. This instrument is capable of detecting changes in distance between the test masses as small as 10 picometres, or one hundred millionth of a millimetre.

A wealth of new gravitational wave data has been collected during the first two observing runs of the LIGO detector and the Virgo interferometer which is based near Pisa. 

In a new paper, scientists from the LIGO and Virgo research collaborations presented data from a total of 10 stellar-mass binary black hole mergers and one merger of neutron stars. Seven of these events had been reported before, while four of the black hole detections are newly announced. 

The data has been hailed as a significant step forward in the fledgling field of gravitational wave astronomy. 

“This remarkable crop of detections show just how valuable gravitational wave astronomy is in developing our understanding of the universe,” said Professor Sheila Rowan, director of the University of Glasgow’s Institute for Gravitational Research.  “In less than three years gravitational wave detections have given us direct evidence of the existence of black holes and binary neutron star collisions. Now we present a wealth of new data from LIGO and Virgo to stand alongside the ground-breaking discoveries already made during their initial observing runs.

“It took science a century to confirm Einstein’s prediction of the existence of gravitational waves, but the pace of our discoveries since then has been exhilarating, and we’re anticipating many more exciting detections to come.” 

Professor Martin Hendry, head of the University of Glasgow’s School of Physics and Astronomy, added: “The four new detections are exciting, particularly the largest and most distant black hole collision we’ve seen to date, but what’s equally significant is that we now have data from 11 detections collected together as a catalogue. 

“That represents a big step forward in our understanding of the universe, and is a ringing endorsement of the effectiveness of gravitational wave astronomy.” 

The University of Glasgow’s gravitational wave research is funded by the Science and Technology Facilities Council (STFC) and in partnership with the Universities of Cardiff and Birmingham, among other UK universities. 

“The next observing run, starting in Spring 2019, should yield many more gravitational-wave candidates, and the science the community can accomplish will grow accordingly,” says David Shoemaker, spokesperson for the LIGO Scientific Collaboration. “It’s an incredibly exciting time.” 

ASTROPHYSICIST JOCELYN STILL SHINING BRIGHT

Forty years ago astrophysicist Jocelyn Bell Burnell was snubbed in favour of her male collaborators who were awarded the Nobel Prize.

Now she is donating a recent £2.3m award for her work to fund a scholarship for female and minority students in physics research.

The University of Glasgow graduate won the lucrative Breakthrough Prize five decades after her discovery of radio pulsars. Her male collaborators were recognised with the Nobel Prize ten years after the ground-breaking work but she was left uncredited despite being the first to spot the pulsars.

However she wants to use her prize, one of the biggest in modern science, to challenge “unconscious bias” in science.

“I don’t want or need the money myself and it seemed to me that this was perhaps the best use I could put to,” said Dame Jocelyn (75).

"I found pulsars because I was a minority person and feeling a bit overawed at Cambridge. I was both female but also from the north-west of the country and I think everybody else around me was southern English," she said.

"So I have this hunch that minority folk bring a fresh angle on things and that is often a very productive thing. In general, a lot of breakthroughs come from left field."

Born in Lurgan, Northern Ireland, she graduated with honours in physics from the University of Glasgow in 1965, before moving to Cambridge where she made her breakthrough.

While examining data from a new radio telescope she helped construct, Dame Jocelyn pinpointed a weak and unusual signal which turned out to be the repeating pulses of radio waves.

She was able to show it originated in space and eventually identified it as a fast spinning neutron star.

The Breakthrough Prize selection committee said her discovery of pulsars stood as “one of the great surprises in the history of astronomy”.

“Until that moment, no-one had any real idea how neutron stars could be observed, if indeed they existed,” said committee chair Edward Witten.

Dame Jocelyn’s leadership in science is also recognised by the award. A champion of young students, especially women, she was the first female president of the Institute of Physics and the Royal Society of Edinburgh and in 2018 became Chancellor of the University of Dundee, after being awarded an honourary degree by the university the previous year. It followed an honorary scientific doctorate which was awarded by the University of Glasgow in the late 90s. Dame Jocelyn is currently a visiting professor of astrophysics at the University of Oxford

Professor Dame Julia Higgins, president of the Institute of Physics, said: “This is an excellent and hugely appropriate acknowledgement of Jocelyn’s work. Her discovery of pulsars still stands as one of the most significant discoveries in physics and inspires scientists the world over.

“Her example of using insight and tenacity to make a discovery that rings through the ages stands her alongside the greatest of scientists.”

“Alongside her scientific achievement, Jocelyn has become a hugely respected leader in the scientific community. She has been instrumental in making sure the issue of access to science by people from under-represented groups is at the very top of the science community’s agenda.”

Dame Jocelyn is unperturbed on missing out on a Nobel Prize, saying she has done very well without one.

“If you get a Nobel Prize you have this fantastic week and then nobody gives you anything else,” she said.

“If you don’t get a Nobel Prize, you get everything that moves. Almost every year there’s been some sort of party because I’ve got another award. That’s much more fun.”