avatarEthan Siegel

Summary

The website content discusses the recent detection of the cosmic gravitational wave background through pulsar timing, confirming a key prediction of Einstein's General Theory of Relativity.

Abstract

In 2023, scientists have reported the first strong evidence of the cosmic gravitational wave background, a phenomenon theorized by Einstein's General Theory of Relativity. This discovery was made possible by observing millisecond pulsars, which act as precise cosmic clocks. The gravitational waves, produced by the movements of massive objects across the universe, create a detectable 'hum' when they pass through the line of sight from these pulsars to Earth. Dr. Thankful Cromartie explains the significance of this finding and the role of pulsar timing arrays in this breakthrough on the Starts With A Bang podcast. This development marks a significant advancement in our understanding of the universe, with pulsar timing becoming the second method to directly detect gravitational waves.

Opinions

  • The discovery of the cosmic gravitational wave background is a major milestone in the field of astrophysics, affirming the predictions of General Relativity.
  • Pulsar timing arrays are recognized as a powerful tool for detecting gravitational waves, complementing other methods like those used by LIGO.
  • The announcement of this evidence in 2023 was somewhat unexpected, indicating a rapid pace of progress in gravitational wave astronomy.
  • The podcast episode featuring Dr. Thankful Cromartie is praised for making the complex science of pulsar timing and gravitational waves more accessible to the public.
  • The author, Ethan Siegel, expresses enthusiasm about the future of gravitational wave research and its potential to reveal more about the universe's most enigmatic objects and phenomena.
The illustration shown here maps out how merging black holes from all across the Universe generate ripples in spacetime, and as those ripples pass across the lines-of-sight from a millisecond pulsar to us, those signals create timing variations across this natural array. For the first time, in 2023, we’ve detected strong evidence indicating the presence of this cosmic gravitational wave background. (Credit: Daniëlle Futselaar (artsource.nl) / Max Planck Institute for Radio Astronomy)

Starts With A Bang podcast #96 — The cosmic gravitational wave background

How scientists are hearing the gravitational background “hum” of the Universe for the very first time.

We all knew, if Einstein’s General Theory of Relativity were in fact the correct theory of gravity, that it would only be a matter of time before we detected one of its unmistakable predictions: that all throughout spacetime, a symphony (or cacophony) of gravitational waves would be rippling, creating a cosmic “hum” as all of the moving, accelerating masses generated gravitational waves. The intricate monitoring of the Universe’s greatest natural clocks, millisecond pulsars, would be one potential way to reveal this cosmic gravitational wave background.

But not many expected that here in 2023, we’d be announcing the first robust evidence for it already, and that future studies will reveal precisely what generates it and where it comes from. Yet here we are, with pulsar timing taking center stage as the second unique method to directly detect gravitational waves in our Universe!

For this edition of the Starts With A Bang podcast, I’m so pleased to welcome Dr. Thankful Cromartie to the show, where she guides us through the gravitational wave background, the science of pulsar timing arrays, and the underlying astrophysics of the objects that we monitor with them: millisecond pulsars. It’s a fascinating story and one that’s more accessible than ever with this latest podcast, and I hope you learn as much as I did listening to it.

Starts With A Bang is written by Ethan Siegel, Ph.D., author of (affiliate links following) Beyond The Galaxy, Treknology, and The Littlest Girl Goes Inside An Atom. His new Encyclopaedia Cosmologica is forthcoming in 2023!

Gravitational Waves
Space
Astronomy
Astrophysics
Podcast
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