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Twenty

Why does it matter?

It's sometimes easy to put science in a box, but we should never forget that it underpins everyday life…

Why does it matter?

Why does it matter

Detecting gravitational waves was the climax of five decades of research and the climax of many scientific careers. The discovery was also universally described as one of the great milestones in physics and astronomy, because it verified a major prediction of Albert Einstein’s 1915 General Theory of Relativity and thus advanced our understanding of the Cosmos and how it was formed.

In the process of developing the instruments required to detect gravitational waves, there have also been several practical spin-offs, including new technologies to monitor the distribution of oil underground and even new devices to measure erosion in buildings and defects in eyes – all developed by scientists working in Scotland.

Scientists who ask for funds for fundamental research are questioned long and hard about the benefits of what they do, and often struggle to justify projects, especially if there is no short-term prospect of concrete results. If they emphasise the innovative spin-offs which this important research may produce, and the business that this will create (especially jobs, profits, exports, etc.), they are usually much more successful in getting the funding they need.

But even though they generate business and also improve human life, the spin-offs from the quest for gravitational waves are only one very small part of the story – no matter how much value they add to the project. Perhaps the greatest contribution of the project is that it will lead to the creation of an entirely new field of science. Now that the detectors (the Laser Interferometer Gravitational-wave Observatory, or LIGO) have been proved to work, planning can start to develop the next generation of bigger and better detectors, to see the Universe in ways we could hardly imagine before Einstein's Theory was published. And who knows what discoveries and spin-offs will come in the future?

“Even though it was not the objective at the start, we should not underestimate the future applications,” says Professor Sheila Rowan, the Director of the Institute for Gravitational Research (IGR) at the University of Glasgow. “We have already seen some unexpected spin-offs. Einstein was not thinking of the economic impact of his theory, but when it comes to relativity, you never know what you'll discover – including the unknown unknowns.”

Rowan highlights several of the spin-offs emerging from Scotland. For example, Professor Giles Hammond, of the University of Glasgow, has developed very small micro-electro-mechanical systems (MEMS) devices that can be used as ultra-sensitive, portable gravimeters for use in applications such as seismography – the same kind of technology used to detect gravitational waves can be used to detect very small variations in the strength of gravity, and thus may help to predict volcanic eruptions.

Professor Siong Heng of the IGR, the co-Chair of the 'burst' working group at LIGO, has been working with Dunfermline-based company Optos to develop new techniques for detecting physical defects in eyes, using similar algorithms to those used for reducing the “noise” which interferes with gravitational waves.

Historic Scotland is using laser interferometers to detect and measure erosion in buildings, and Stuart Reid, Professor of Experimental Physics at the University of the West of Scotland, has applied the same technology used to calibrate the mirror suspensions (key components of the laser interferometers) to “nanokick” stem cells, helping them to grow new bone, blood or muscle. (For more details, please see story on page 44.)

These innovative solutions have emerged thanks to other breakthroughs in technology, while building the detectors. For example, to make the interferometers work more efficiently, you have to isolate the laser beam inside a vacuum, and this has led to advances in vacuum tube technology. Improvements in mechanical and optical bonding may lead to advances in applications such as photonics on, both the ground and in space. The laser beam may cause variations in power which lead to false alarms in the search for real gravitational waves, so the challenge is to make it as stable as possible, and this is what makes possible some new techniques for surgery, using similar lasers. The LIGO detectors have to measure tiny changes in the distance between their mirrors and this has also led to advances in studying the mechanical and optical properties of various materials used to make the highly reflective coatings for the mirrors, and for the mirrors themselves.

“Fundamental research does bring benefits,” says Rowan, “but these are not so obvious or recognised enough. It’s sometimes easy to put science in a box, but we should never forget that it underpins everyday life.”

The human factor

Another major factor in LIGO's success is the fact that so many scientists from countries all over the world are involved, from graduate students to senior professors – all of whom have dedicated years of their lives to work on something which may never bear any fruit, even though it may be of great fundamental importance.

Mindful of this global dimension, and the fact that the project might have gone on forever without proving Einstein's great theory, Professor Harry Collins of the University of Cardiff has studied the collaboration since it began, to see what lessons can be learned for future projects on such a massive international scale.

As well as the importance of teamwork and collaboration among different countries, there are fundamental scientific lessons to learn: “The LIGO project is a touchstone of how science works,” says Professor Martin Hendry, Head of the School of Physics and Astronomy at the University of Glasgow and Chair of the LIGO Education and Public Outreach Group. “Many scientists doubted we would ever detect gravitational waves, including Einstein himself. That is why the project is such a good example of the need for verification, because no matter how much you want a theory to be true, you have to verify the data before you can prove it.”


More detections

After waiting 50 years to detect gravitational waves, the second discovery happened just 16 weeks later, on December 26, 2015 – another instance of compact binary coalescence 1.4 billion light years away. Unlike the first detection (where the signal was obvious against the background 'noise' of the instruments), it was not immediately clear that there was a gravitational-wave signal embedded in the data – the signal was weaker because it came from smaller black holes, and harder to see because it lasted for a second compared to 0.2 seconds. In January 2017, a third event was detected, about twice as far away as the first two events.

 

Image - Gravitational waves are tiny ripples in the fabric of space-time caused by astronomical events

 

 

 

"Why does it matter?". Science Scotland (Issue Twenty)
Printed from http://www.sciencescotland.org/feature.php?id=311 on 23/09/17 06:43:03 AM

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