Musings of a Cancer Doctor

Abstract

One of the delights of science is how captivating the results can be. About 1.3 billion years ago, and incredibly far away, two black holes spiraled together, collided at half the speed of light, coalesced into a single black hole, and in that joining three suns worth of mass were turned into energy in the form of gravitational waves. In September of last year the sound of that collision (literally a sound: you can hear it at https://www.youtube.com/watch?v=TWqhUANNFXw) was recorded by the Advanced Laser Interferometer Gravitational-Wave Observatory’s (LIGO) parallel scientific instruments in Washington and Louisiana. The waves reached Louisiana 7 milliseconds before Washington, suggesting a location in the Southern hemisphere. The result, predicted 100 years ago by Albert Einstein, simultaneously proves the existence of black holes and launches gravitational astronomy as a new field of scientific endeavor. How wonderful. Gravity is both incredibly weak and impressively strong. It is the weakest of the four fundamental physical forces in nature, some 38 orders of magnitude weaker than the strong force, 36 orders of magnitude weaker than the electromagnetic force, and 29 orders of magnitude weaker than the weak force. But at the macroscopic scale it dominates, affecting the trajectory of heavenly bodies and of humans walking around here on earth. Try jumping into the sky and see how far you get What we know about gravity results largely from the scientific work of the two smartest humans who ever lived, Isaac Newton and Albert Einstein. Newton discovered the inverse-square law of universal gravitation, summarized in this equation: