gravity wave notes

Basically, gravity waves are another form of electromagnetic radiation like light waves & radio waves. When a pulse of current flows through a wire, you get an electromagnetic wave in the form of photons flying out. When a large amount of mass appears or disappears, you theoretically get a gravity wave in the form of spacetime shrinking & expanding. Specifically, spacetime briefly shrinks in 1 direction & expands in the perpendicular direction.

At great expense, our ancestors built 2 observatories which could detect the warping of spacetime. In each observatory, 2 lasers are shot 1000 miles back & forth down the length of 2 tunnels arranged in an L. The lasers are in phase when the 2 tunnels are the same length. The lasers go out of phase if the tunnels change length due to a warp in spacetime.

The 2 observatories are 1000 miles apart. The propagation delay between the 2 observatories could triangulate the origin of the gravity wave.

Long ago, 2 black holes collided, converting the mass of 3 suns into a gravity wave & releasing 50 times the energy of all the stars in the universe. 4 months ago, 1 observatory detected spacetime warping by a fraction of the width of a proton. 7ms later, the other observatory detected it. For 1/10 a second, the length of the tunnels in the 2 observatories oscillated as spacetime expanded & contracted several times.

The hope is more gravity wave observatories can be built, detecting more mass change events & making this part of the electromagnetic spectrum as accessible as radio astronomy. It's a testament to the improvements in space transportation that a pathfinder for a space based gravity wave sensor was already launched. The final sensor would have lasers measuring warps in spacetime in a span of 5 million km.

https://journals.aps.org/prl/abstrac...ett.116.061102

https://www.ligo.caltech.edu/images