News broke yesterday that gravitational waves have finally been detected. First predicted by Einstein in 1915, gravity waves are basically ripples in spacetime. They’re created any time any mass accelerates; I suppose even an electron creates them. But they are so faint and difficult to detect that it takes truly monumental events to make them detectable. In this case, two black holes, one 29 solar masses, the other 36, were in close orbit 1.3 billion years ago. They spiraled into each other and coalesced into a single larger black hole. However, rather than forming a black hole of 65 solar masses, the new black hole only masses 62 solar masses. The mass of three suns simply vanished… radiated away in the form of gravity waves. Imagine three suns being converted *entirely* to energy in a split second; that’s the power generated here. And the power wasn’t sent out as a flash of hard radiation or a massive shockwave; instead it was sent out as a massive distortion int he fabric of reality.
Two gravitational wave detectors have been built, one in Louisiana and one in Washington. The principle of operation is a bit difficult to explain… but in short, each detector is an L-shaped construct with legs several miles long. Each leg houses a path for a laser beam; if a gravity wave wanders by it will very slightly change the length of the detector. The laser beams sent down each leg are extremely finely calibrated and measured; the way their individual waves interact with each other when they bounce back shows any change in beam path length. The fact that two detectors are located in different parts of the country means that a few microseconds difference might separate the detection times of gravity waves. This permits some rough triangulation, pointing out the direction of the event. In the recently announced case, both detectors picked up the same signal. The signal was detected in September; it has taken the team of scientists until now to go through the data to make sure they got what they thought they got.
Gravity wave detection doesn’t seem to have any immediate practical application… we won’t be using this to make anti0gravity engines or gravity deck plating for spaceships anytime soon. What it is good for is a new way to examine the universe. Right now it’s not like a telescope, looking out into the universe to see images; it’s more like a simple radio antenna, *listening* to the universe. Whenever we look at or listen to the universe in a new way, we learn new things that we didn’t even suspect before.
It’s not too likely, but one thing a sufficiently sensitive detector might pick up is intelligent signalling. How? Well, imagine an *astoundingly* advanced civilization. Kardaschev Type III or beyond civilizations might be able to grab a neutron star or a black hole and rapidly shake it. This would require vast expenditures of energy to accomplish, but the energy would be converted into gravitational energy, radiated out in waves. These waves, unlike electromagnetic radiation, would not be blocked by dust clouds. Speculatively, gravity waves might be detectable by some hypothetical life forms composed of dark matter… or even across boundaries between one universe and another.
