'We Don't Planet' Episode 8: Gravitational Waves

When Albert Einstein first began developing what would eventually become the theory of general relativity , he probably wasn’t suspecting the full implications of what his explanation of gravity would entail. Perhaps most surprisingly, but discovered by Einstein himself, is that gravity makes waves. These waves travel at the speed of light, and are created anytime there’s an asymmetry in the gravitational interaction of two bodies. This situation is very common in the universe, so gravitational waves should be sloshing around the Earth constantly.

Gravitational waves are literally waves of space-time, so as they pass through an area, they alternatively stretch and squeeze objects. Imagine being pulled and squished like a piece of silly putty — the alternating action of gravity as the wave passes through does pretty much the same thing.

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But gravity is by far the weakest force, and gravitational waves are a small perturbation on top of it, so it took 100 years to finally detect them with the LIGO (Laser Interferometer Gravitational-Wave Observatory) instrument in the fall of 2015. And the waves LIGO detected were from a truly impressive event: the merger and coalescence of two black holes, each weighing in at dozens of solar masses. Even then, the confirmed gravitational waves barely nudged the sensitive LIGO apparatus by less than the width of an atom.

“We Don’t Planet” is hosted by Ohio State University astrophysicist and COSI chief scientist Paul Sutter with undergraduate student Anna Voelker. Produced by Doug Dangler, ASC Technology Services . Supported by The Ohio State University Department of Astronomy and Center for Cosmology and AstroParticle Physics . You can follow Paul on Twitter and Facebook .

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