Glasgow Making Waves (by Measuring Them)

Glasgow University’s Institute for Gravitational Research are back at it again folks. After co-leading the group behind the first detection of gravitational waves at LIGO in February 2016, the Laser Interferometer Gravitational-wave Observatory, a team lead by the Kelvin Building’s own Dr. Harry Ward has been awarded the Sir Arthur Clarke award for their contribution to space exploration. The team, working for the LISA Pathfinder, have contributed a significant amount of work behind the development of an Optical Bench Interferometer, an OBI (the acronyms do not stop in astronomy). In essence, the OBI is capable of measuring the distance between two masses with a precision ranging in picometres. If that doesn’t sound impressive, the helium atom diameter is calculated to be 62 picometres, 0.0000000000062 meters. A distance a bit too small to measure with the ruler at the bottom of your bag.

The LISA Pathfinder has already set up a laboratory orbiting the Earth that contains two gold-platinum cubes, each 46mm in length and 38cm apart. They’ve managed to get these blocks to be locked in an almost perfect gravitational free-fall, where the only force they experience is gravity. Any other forces experienced, even tiny ones caused by particles from the Sun hitting the laboratory which is not protected by the luxury of the Earth’s atmosphere, are cancelled out by micro-thrusters. The result is the two blocks appearing perfectly stationary. The distance between the two can only be changed by space itself stretching and shrinking: the exact effect of a gravitational wave passing by.
The OBI created by the team at Glasgow shows us that the precision necessary to detect tiny changes in spacetime due to these waves is now available. This has paved the way for ESA’s (European Space Agency) plans for the early 2030’s: to replicate the experiment, with the blocks separated by almost 1 million kilometres in space. At this distance, the changes in the distance between the two blocks will be observable by the OBI, and a gravitational wave observatory in space will be operational. Einstein would be absolutely buzzing.

[Ben Taysum –@ben_taysum]


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