As the end of the article discusses, this means that scientists have a whole new way of observing the universe. What we saw before was mostly along the EM spectrum—radio waves, visible light, etc. This is a way of looking at distortions in the actual fabric of spacetime.
Hard to say what the practical applications will be, but it's akin to asking Galileo what the practical applications of a telescope are. There probably aren't any if you're a 17th-century merchant or something, but a few decades down the line…
It seems to my understanding that the power needed for us measure the gravitational waves needs to be enormous - so big in fact that these colliding events only happen once every 10000 years. Can we use gravitational waves also to measure other stuff and not just super powerful rare events?
The waves are produced by mass accelerating through spacetime, so in theory everything produces them—you, me, a black hole, a neutron star. As physicists learn to tune their instruments, more sources of the waves will be within reach. But you're right: the odds of detecting a signal this strong and clear right off the bat were low. If LIGO hadn't happened to be on when the waves reached it, after 1.3 billion years of traveling through the cosmos, they would've been missed completely. So this was a mix of extraordinary science and extraordinary good luck.
> so big in fact that these colliding events only happen once every 10000 years.
If you read the article you would see that they expect to see events daily within a few years. It will become similar to optical observations with telescopes.
Exactly, and the big thing there is that these accelerations happen conveniently before the interesting events.
When 2 neutron stars circle each other, they'll start sending out gravitational waves. This will start to occur centuries before they collide, but they increase exponentially until the collision happens. Today they cross the detection threshold a few minutes before the actual collision, depending on their size. If we can get that up to a few hours or a few weeks we can use this to point every telescope in the world in the right direction before the flash of the collision happens.
So an immediate application is simple : it gives us advance warnings of large events in the cosmos. This means a lot of instruments dedicated to studying huge-energy events no longer has to look at the entire night sky, or get lucky, but we can actually get a signal before they happen.
In theory, if we can get the instruments accurate enough, we should be able to detect even smaller events like a supernova. A gravitational wave should be generated a few hours before the flash.
Hard to say what the practical applications will be, but it's akin to asking Galileo what the practical applications of a telescope are. There probably aren't any if you're a 17th-century merchant or something, but a few decades down the line…