Modern Physics
Gravitational Waves
We've primarily dealt with light and sound waves in this chapter, but that doesn't mean they're the only type of waves. We touched on things like the ocean or physical wave motion like yo-yos, but there's another important category of waves that's become prominent ever since this crazy Swiss patent clerk named Einstein dreamed them up: gravitational waves.
The basic idea behind gravitational waves (not to be confused with gravity waves, which describe normal ocean waves) is that massive objects in the universe can distort space itself. These distorting objects have to be really, really big—think binary stars in a galaxy far, far away or giant supernovas—and they actually bend the fabric of the universe around them, the way a trampoline deforms under your weight. These creases oscillate outwards in the same way a wave travels along the surface of a drum when it's struck. 6
The reason things don't go all funhouse mirror on you every time a distant star explodes is simple: the amplitude of gravitational waves is tiny. Scientists predict gravitational waves will stretch space by a factor of 1×10-20 by the time they reach earth—which means a 1 m object is elongated by less than one percent of an atom's radius. 7
Measuring a wave this small presents a whole new set of challenges beyond Doppler radar or tuning guitars. Physicists have constructed several multi-kilometer long observation stations such as LIGO, the Laser Interferometer Gravitational-Wave Observatory.8 These use specially tuned lasers that are bounced back and forth over kilometers until a gravitational wave strikes them, which should stretch the tunnels enough that the lasers fall out of sync with each other and destructively interfere.
Scientists haven't directly observed these tiny waves yet, but most aren't ready to call Einstein wrong. A paper on general relativity and a Nobel prize turn out to be worth a bit more than shaky handy-cam Bigfoot footage when it comes to convincing the scientific community something's out there and worth looking for.