In 1915 Albert Einstein put forward his theory of general relativity (1), which predicted gravitational waves – waves which transport energy as gravitational radiation from huge space events. He stated, although these waves existed they would be too weak to ever detect.
Yet one hundred years after Einstein’s prediction, employees at LIGO, The Laser Interferometer Gravitational-Wave Observatory, announced the direct detection of gravitational waves (2), confirming Einstein’s theory and causing scientists around the world to reach for the nearest glass of champagne. Now the waves have been detected, the fun can begin.
Einstein’s theory says that masses (such as the sun) would cause the warping of space-time around them. You can think of space-time as a piece of cling film stretched over a container. Placing a boiled egg on the cling film would create a dip warping the cling film, just as the mass of a sun would warp space-time around it. A slight distortion in this space would distort nearby regions, causing ripples in the curvature of space-time namely gravitational waves.
Professor Stephen Hawking described how the detection of such waves is a stepping stone for science telling BBC news (3) “Apart from testing (Albert Einstein’s theory of) General Relativity, we could hope to see black holes through the history of the Universe. We may even see relics of the very early Universe during the Big Bang at some of the most extreme energies possible.”
Gravitational waves, unlike light, are hardly affected by what they pass through so carry and hold the information sent out from an astronomical object, such as a black hole or neutron star. These waves will allow astronomers to observe the predicted wonders of the night sky in a whole new way leading to further astronomical discoveries.
Even more exciting is that the waves act as time windows into the past. The deeper into the universe you “look”, the further back in time you observe, and with gravitational waves we can go deeper than ever before. There is even a possibility that we could look all the way back to the beginning as Professor Bernard Schutz, from Cardiff University told BBC (3) “With gravitational waves, we do expect eventually to see the Big Bang itself.”
Combining this new look of the universe and these time windows into the past, gravitational waves may offer the physicists greatest Christmas present – the grand unification of forces or the “Theory of everything”. Currently Einstein’s theory of general relativity (which describes the large) and quantum mechanics (which describe the small) do not gel with each other. It is one day hoped, by scientists such as Stephen Hawking, that the theory can formulate an equation that explains all physical phenomena.
Thanks to LIGO’s gravitational wave discovery physics is about to enter a new golden age. Up until the 16th century we believed Earth to be a flat planet with an edge, but now we dismiss the idea. Will humans in the future be laughing at us for believing in Einstein’s ridiculous theories or will they herald him as we do, as one of the greatest minds of all time? Space-time will tell.
By Luke Molloy, 2nd Year Physics
(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) News | Gravitational Waves Detected 100 Years After Einstein’s Prediction | LIGO Lab | Caltech . 2016. News | Gravitational Waves Detected 100 Years After Einstein’s Prediction | LIGO Lab | Caltech. [ONLINE] Available at: https://www.ligo.caltech.edu/news/ligo20160211. [Accessed 13 February 2016].
(3) Einstein’s gravitational waves ‘seen’ from black holes – BBC News. 2016. Einstein’s gravitational waves ‘seen’ from black holes – BBC News. [ONLINE] Available at: http://www.bbc.co.uk/news/science-environment-35524440. [Accessed 13 F
Image from: https://www.seeker.com/space/gravitational-waves-from-colliding-neutron-stars-detected-for-the-first-time