Timing Waves

Daniëlle Futselaar (artsource.nl) / Max Planck Institute for Radio Astronomy Illustration of merging black holes and their effect on pulsars and Earth. Pulsars are incredibly precise cosmic clocks. So precise that we can use them to measure subtle changes in their position thanks to the Doppler effect. Pulsar timings were used to prove the existence of gravitational waves long before we could observe them directly. This has led to the idea of a pulsar timing array (PTA). Observe lots of pulsars over time, then look at their timing shifts statistically to study gravitational waves on a cosmic scale. A good PTA example is the NANOGrav project, which looked at 67 pulsars over the course of 15 years. They hoped to discover evidence of early cosmic inflation, which is the accepted model for explaining several cosmological mysteries. In theory, the rapid inflation of the universe just micro-moments after the Big Bang should have filled the cosmos with a distinct background of gravitational…