Hard Science — October 24, 2022
How fast is gravity, exactly?
- Thanks to observations of gravitational waves, scientists were able to settle a longstanding debate over the speed of gravity.
- Throughout history, scientists have proposed many answers for the exact speed of gravity.
- Broadly speaking, the two main propositions have been that gravity is either infinitely fast or as fast as the speed of the light.
- Thanks to observations of gravitational waves recorded in 2017, we now know that gravity and light travel at the same speed.
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While gravitational radiation was predicted back in 1916, it took scientists nearly a century to develop the technology to detect it. To detect these distortions, scientists take two tubes, each about 2.5 miles (4 kilometers) long, and orient them at 90 degrees, so they form an “L.” They then use a combination of mirrors and lasers to measure the length of both of the legs. Gravitational radiation will change the length of the two tubes differently, and if they see the right pattern of changes of length, they have observed gravitational waves.
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So, that’s the answer. Gravity and light travel at the same speed, determined by a precise measurement. It validates Einstein once again, and it hints at something profound about the nature of space. Scientists hope one day to fully understand why these two very different phenomena have identical speeds.
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Not only do I NOT understand the point that they are making. It gives me a headache to read about it. YMMV, but all the same very interesting.