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LIGO - An extraordinary collaboration across the globe

13 October 2020

Nobody is an island, and collaboration is essential to life.

Learn how an extraordinary collaboration between theoretical and experimental physicists across the globe, turned Einstein's theories into a revolutionary telescope.

About 1.4 billion years ago (when all life on Earth lived in the oceans, and was still evolving from single-celled to multi-cellular creatures), and about 1.4 billion light years away, two Black Holes were in a shrinking and accelerating death spiral.

These two Black Holes (29 and 36 times heavier than our Sun) then smashed into each other - at half the speed of light.

We detected the last two-fifths of a second of their death spiral.

Back on September 14, 2015, we humans detected our very first Gravitational Waves. Gravity is a very weak force, so only truly extreme events will produce detectable waves (at least, with our current technology.)

A pair of Black Holes colliding into each other turns out to be that kind of cataclysmic event. In that collision, about three times the mass of our Sun got converted into pure energy.

In that brief instant, the collision generated more than 50 times the combined power output of the billion trillion-ish stars in the entire known Universe. That enormous power spread out in all directions as Gravitational Waves.

But by the time the power had rippled across the Universe to us, it was a lot weaker.

As the biggest of those Gravitational Waves rippled through our planet, it changed our planet’s size and shape. Earth is about 12,750 kilometres across. Our globe shrank, and then expanded, by a very tiny amount – roughly two-and-a-half times the diameter of a proton, about 2.5 times a thousandth of a trillionth of a metre.

Image: LIGO measurement of gravitational waves — LIGO measurement of gravitational waves. Shows the gravitational wave signals received by the LIGO instruments at Hanford, Washington (left) and Livingston, Louisiana (right) and comparisons of these signals to the signals expected due to a black hole merger event.

Credit: B. P. Abbott et al. (LIGO Scientific Collaboration and Virgo Collaboration).

There’s no way our ordinary human senses could have detected this tiny change.

But an extraordinary collaboration between Theoretical and Experimental Physicists from across the globe, covering a century, made it possible. Scientists invented, and used, a revolutionary “telescope” called the Laser Interferometer Gravitational Wave Observatory (LIGO).

In 1915, Albert Einstein came up with his General Theory of Relativity (actually a Theory of Gravity). One of Einstein’s many great insights was to treat both Space and Time as real things. He was the first to see Gravity as a distortion of Space-Time. Einstein said that any accelerating mass would give off Gravitational Waves, which would then ripple through the background fabric of space-time at the speed of light.

But to turn Einstein’s theories into LIGO took a century, and an enormous international collaboration. The names of the authors (over 1,100 of them) took up some 123 lines of the paper, and they came from countries around the world – Brazil, Poland, India, the USA and dozens more, including Australia.

On that day, 14 September, 2015, at 3.58pm Australian Eastern Standard Time, Tony Abbott was deposed as the Australian Prime Minister, and replaced by Malcolm Turnbull.

At 7.50 pm AEST (232 minutes later) scientists detected (for the very first time) a Gravitational Wave as it swept through the Fabric of Space-Time, and our planet. They wrote a paper on their astonishing discovery.

And who were the first three authors of the Gravitational Wave paper?

Abbott, Abbott, and Abbott!

Coincidence, or was our ex-PM actually a secret collaborating author? You decide …