Gravity

Gravity (not the song by John Mayer​ but the force) is in the news. More specifically, gravity waves are in the news.

Predicted by Albert Einstein 100 years ago, gravity waves are extremely difficult to detect. Just how difficult I didn't know until I read an article in Science Newsline​:

At each observatory, the 2 1/2-mile (4-km) long, L-shaped LIGO interferometer uses laser light split into two beams that travel back and forth down the arms (four-foot diameter tubes kept under a near-perfect vacuum). The beams are used to monitor the distance between mirrors precisely positioned at the ends of the arms. According to Einstein's theory, the distance between the mirrors will change by an infinitesimal amount when a gravitational wave passes by the detector.A change in the lengths of the arms smaller than one-ten-thousandth the diameter of a proton (10^-19 or 0.0000000000000000001 meter) can be detected.

Measuring something that small is truly amazing. Hats off to all involved.

Now, where is my star ship?