In a new video from Physics World, scientists from the Jodrell Bank Observatory near Manchester in the United Kingdom discuss how natural time keepers called pulsars — which are actually the condensed left-over material from burned-out stars — could help the search for gravitational waves. Einstein predicted that very massive, energetic events (like two stars merging together) could create ripples in the fabric of space, the way a stone creates ripples on the surface of a pond. The ripples aren't made of light or matter, but of space itself. These are called gravitational waves .

So far, astronomers have not been able to detect gravitational waves directly, and some astronomers are choosing to take an indirect path. Pulsars earned their name because their light appears to pulse on and off. In some cases, the pulsar's blinking is so regular, it exceeds the precision of any clock that can be built by humans. An interruption in that regularity, therefore, must come from an external event. Check out the video to see how interruptions to these regular pulses of light could indicate the presence of gravitational waves.

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