Professor Martin Hendry : Einstein’s Universe
Professor Martin Hendry set the scene by observing that Lord Kelvin had asserted in 1900 that Physics is ‘finished’! Fortunately for Professor Hendry this proved not to be the case career-wise.Kelvin’s position reflected the technological limits of his time. However, Einstein’s Theory of Relativity, a few years later (1905), showed Kelvin’s position was misjudged. Nonetheless Prof Hendry noted that it has taken another 100 years or so for Einstein’s Gravitational Wave prediction to be proved.
Putting things in context Prof Hendry observed that Newton’s Laws of Gravity (circa 1686) worked well enough to explain an apple falling and get man to the Moon. Einstein’s theory has also proved resilient for the last 100 years. However, a new Quantum Gravity Theory has emerged from Prof Hendry’s and colleagues’ work. It is still to be fully established and it may be another 100 years before it is fully understood.
The problem with gravitational waves is that it takes big events such as two neutron stars or black holes coming close together to generate them. Prof Hendry drily noted a brick in the spin dryer, even on the high speed spin, doesn’t do it. (Not to be done at home, children!) It’s also true that as gravitational waves spread like expanding ripples over interstellar distances that the instruments to measure them require to be extremely sensitive (eg 1:1000 the width of a proton). Glasgow University is extremely proud to have developed an instrument that can make such fine measurements.
Prof Hendry demonstrated the design problem by getting members to stamp their feet while he verbally mimicked the sound of a gravitational wave. Of course, he was inaudible! For this reason you need more than one interferometer widely separated to ensure different background noises which can be eliminated. Thus the first successful detection of gravity waves in 2015 was by two detectors about 3000 kilometers apart in the USA. The final proof positive of Einstein’s Gravity Wave prediction! By 2021 Prof Hendry hopes there will be six detectors across the world which should be able to detect hundreds of gravitational waves each year.
It took 5 months of careful analysis to confirm the results. During this time it was established that the waves were caused by the collision of two Black Holes with a mass of 36 and 29 times the sun respectively and the event took place about 1.3 billion light years away (in a Galaxy far, far away, a long time ago – get it?).
Professor Hendry’s final message is that the discovery of gravitational waves means that we are on the threshold of a new era. He fully expects it will take another century to unravel the mysteries. No doubt by this time another frontier will be found and, once again, physics will not be finished! For those who want to know more go to : www.ligo.caltech.edu