How do you measure ultra-low-frequency gravitational waves coming from the centres of distant galaxies?
By observing their effect on cosmic clocks of course!
This episode Dr Michael Keith, an astrophysicist at the University of Manchester, reveals how detecting subtle changes in the regularity of pulsars is providing a new way of observing the cosmos.
You can watch the video and listen to the audio versions of this podcast below.
Find out more about the discovery via our news story 'Galaxy-sized' detector measures echos of colliding black holes
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Audio
Listen to more episodes of the Radio Astronomy Podcast or check out the BBC Sky at Night Magazine YouTube channel.
