'Music' of gravitational waves
The Advanced Ligo experiment, which aims finally to detect ripples in the fabric of space-time, is up and running.
Gravitational waves are a prediction of Einstein's Theory of General Relativity, and should be generated by violent events, such as the merger of black holes and neutron stars.
The frequency of many waves is expected to be around 100 Hz, which means that scientists can describe these cosmic phenomena in terms of sound because that frequency is in the human auditory band.
Ligo scientist Vern Sandberg explained this concept to our correspondent Aleem Maqbool.
This audio sequence is taken from The Documentary: A New Ear on the Universe, which will be broadcast on the BBC World Service on Saturday, 26 September. Presented by Aleem Maqbool, and produced by Adrian Washbourne, the programme will also be available online.
18 Sep 2015