this post was submitted on 07 Jul 2023
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Physics

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Opinion: I’m a physicist. Last week’s gravitational waves announcement sent me reeling. (www.washingtonpost.com)
submitted 1 year ago* (last edited 1 year ago) by [email protected] to c/[email protected]
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But a gravitational wave? That’s a distortion of space-time itself — a stretching and squeezing of the fabric of reality, a wave of deformation tearing through the cosmos, warping everything in its path. The monstrous denizens of the intergalactic deep reveal themselves not through the light they emit but by how they stir the space-time we share. When a gravitational wave moves through you, you are, for a moment, a different shape.

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[–] [email protected] 9 points 1 year ago* (last edited 1 year ago) (1 children)

It's a great discovery. I like the poetic spirit of the author, but at the same time I think it can be quite misleading in the present misinformation age. "You are a different shape" also as the Moon rotates around the Earth, for example – it's tidal forces in both cases. Actually the "distortion of you" might be stronger owing to the Moon than to gravitational waves – have to compare their order of magnitude.

[–] [email protected] 2 points 1 year ago (1 children)

Or sound waves, literally pressure waves. We can hear or feel them because they deform our body.

[–] [email protected] 3 points 1 year ago

There are similarities, and also two differences. Pressure deforms the surface of a body, and the deformation can then propagate inwards, depending on the stiffness and elasticity of the body. Gravitational/tidal waves deform the curvature of spacetime within the body all at once. Pressure is force exerted by matter (including electromagnetic fields) on matter; so in a vacuum, pressure would not be possible. Gravitational waves are not "exerted" by matter (although they are generated by matter far away), and they are possible in vacuum.

But that said, the final effect is the same: distances between parts of a body change.