I wanted to write more about LIGO earlier because it's incredible but my battery was low. it's one of the most advanced pieces of equipment in the US, consisting of two observatories with two 4km laser tubes each.

in order to measure gravitational waves passing thru Earth, it has the ability to measure a tiny warping in spacetime of the magnitude of one thousandth of the diameter of a single proton. (!)


they do this by firing a laser thru a splitter down both of the tubes, each of which has a mirror at the end. the beams normally return and perfectly cancel each other out because they interfere with each other. but when space is bent, the distances the two beams travel is different, so they get out of phase, and the detector picks up a signal.

the machines are so sensitive that before they installed active dampening, an earthquake anywhere on Earth would throw off their detection ability, but their resistance to noise has increased dramatically in the past few years.

the sensitivity is the equivalent to detecting the width of a human hair at the distance of the Proxima Centauri star system.



@technomancy LIGO is awesome, I've added a tour to my bucket list, right after returning to CERN and getting to see inside the accellerator which was not on my otherwise amazing CERN tour.

You know, there's a satellite based LIGO on the drawing board, the Laser Interferometer Space Antenna. Much longer beam lengths, potentially much more accurate.

@joeyh yeah they mentioned LISA tho it is over a decade away I think. sounds like it could cover a much wider frequency range as well.

really looking forward to taking my KIIS to CERN in a few years.

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