PBS Space Time PBS Space Time

Gravitational Wave Background Discovered?

Sep 17, 2026 · 24m

Summary

This episode explores the tentative detection of the gravitational wave background by the NANOGrav collaboration using a pulsar timing array. The host explains how millisecond pulsars act as galactic clocks to detect low-frequency ripples from supermassive black hole mergers or cosmic inflation, contrasting this with LIGO's high-frequency observations. The discussion covers the physics of spacetime curvature, the loss of the Arecibo observatory, and the potential for these findings to reveal physics beyond the Big Bang.

Topics discussed

Sponsor: LinkedIn and Instagram ads Introduction: Detecting the gravitational wave background LIGO and the detection of merging black holes The concept of the gravitational wave background Pulsar Timing Arrays as galactic detectors Frequency limits: LIGO vs. space-based observatories Sponsor: LinkedIn and Instagram ads Sources of low-frequency gravitational waves What are pulsars and how they work Using pulsar timing to detect waves The quadrupole antenna pattern Sponsor: LinkedIn and Instagram ads Correlations in pulsar timing residuals NANOGrav collaboration and Arecibo observatory NANOGrav's tentative detection of the background Sponsor: LinkedIn and Instagram ads Analyzing the spectrum and future implications Promo: Overview, a new science show Comments: Dark matter and the equivalence principle Sponsor: LinkedIn and Instagram ads Comments: Gravity, gravitons, and time dilation Sponsor: Uber Eats and Silicon Valley Bank Sponsor: McDonald's Big Mac meal
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