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  • 11May

    Gravitational waves – Why should I care?

    On Thursday 11th February scientists at LIGO, The Laser Interferometer Gravitational-Wave Observatory, confirmed that they directly detected gravitational waves by observing two black holes merging.

    In 1915 Albert Einstein put forward his theory of general relativity (1), which predicted gravitational waves – waves which transport energy as gravitational radiation. One hundred years later rumours have surfaced that LIGO, The Laser Interferometer Gravitational-Wave Observatory, have finally directly detected gravitational waves and proved Einstein right, as reported by New Scientist magazine. (2)

    Einstein predicted that large masses (such as the sun) would cause the warping of space-time around them. A slight distortion in this space would distort nearby regions, causing ripples in the curvature of space-time called gravitational waves. These waves have long been thought to be real physical phenomena but have only been. For example, the Hulse-Taylor binary system consists of a pulsar and a neutron star losing energy as they spiral into each other. This loss of energy can only be explained if it is being carried away by gravitational waves, further explained by the University of Cardiff (3). These waves have long been thought to be real physical phenomena but have only been detected indirectly.

    However now it is suspected that LIGO have measured at least three gravitational wave signals in the past six months, an incredible feat. Rumours such as this have surfaced in the past and have resulted in unconvincing signals being detected, yet New Scientist believes this could be the real deal.

    As described in the magazine, the detectors are 3000km apart and attempt to detect the stretching and contracting of space as the gravitational waves pass by (2). Between the detectors is a light beam which is measured with a precision of 10-19m (approximately one-tenth thousand the diameter of a proton). Such precise equipment is required as gravitational waves only give the smallest of signals.  A change in length of the light beam should be detected as a gravitational wave ripples past.

    If LIGO have ended the hunt the implications would be huge. As LIGO scientist Amber Stuver states on her blog (4), Einstein’s theory of general relativity can be put to new tests like measuring the speed of gravitational waves and validating that they travel at the speed of light as theorised. In addition, we can use gravitational waves to investigate unknown phenomena in space such as neutron stars merging into one star, and the ramifications this has.

    The one hundred year search may soon come to an end. Is Einstein about to have one final victory or will the hunt continue? Space-time will tell.

     

    (1) Einstein, A. 1916. Translation Lawson, R 2016. [ONLINE] Available at: http://www.emu.dk/sites/default/files/relativity.pdf. [Accessed 10 February 2016].

    (2) Sokol, J, 2016. Latest rumour of gravitational waves is probably true this time. New Scientist

    (3) 3. The Hulse-Taylor Pulsar – Evidence of Gravitational Waves. 2016. 3. The Hulse-Taylor Pulsar – Evidence of Gravitational Waves. [ONLINE] Available at: http://www.astro.cardiff.ac.uk/research/gravity/tutorial/?page=3thehulsetaylor. [Accessed 09 February 2016].

    (4) Stuven, L. Living LIGO: Q: How can gravitational waves help mankind?. 2016. Living LIGO: Q: How can gravitational waves help mankind?. [ONLINE] Available at: http://stuver.blogspot.co.uk/2012/01/q-how-can-gravitational-waves-help.html. [Accessed 09 February 2016].

     

    Written by: Luke Molloy

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