Detection of Gravitational Waves?
Yesterday evening, I was on the way to the pub with a colleague when I looked at my phone. I had 5 work new emails, all of them discussing a rumour that an announcement due to be made this Monday by the team in charge of the BICEP Telescope in Antarctica. By the time I got home after the pub, I had had a further few emails, and there was also an article on The Guardian website confirming the rumour.
Gravitational waves are the last piece of Einstein’s jigsaw. In 1916 he published his Theory of General Relativity, which made sweeping predictions as to how the universe works. Over the past century, every aspect of his theory has been rigorously tested and proved to be, at least at our current level of understanding, true. That is, every aspect, except gravitational waves. These have alluded everyone so far, and there have been plenty of attempts. Joseph Weber thought he had discovered them in the 1960s with a type of detector consisting of a large bar of metal with sensors attached. It turned out to be a false alarm though, and efforts since then have focused more and more on using light itself as the metre stick. Two techniques currently used to try to detect the waves are pulsar timing arrays and laser interferometers.
The first technique is the one used by the BICEP Telescope who might announce something on Monday. This involves looking for changes to signals in large datasets, signals which might have been caused by passing gravitational waves. As such this would be referred to as an ‘indirect’ detection. The second technique is one of the few ways in which we could hope to make a direct detection, a detection that involves gravitational waves physically interacting with the test apparatus. The Advanced LIGO and Advanced Virgo telescopes are likely to be the first to make detections when they come online in the next few years.
I work as part of the collaboration of universities developing these new interferometers and thinking of ways to improve their sensitivity. I don’t know too much about the pulsar timing array research, but this is big news for my field if this turns out to be a detection. I am looking forward to the news conference on Monday!