Just today, February 11th, scientists announced that they have confirmed the existence of “gravitational waves” which are the final prediction of Einstein’s theory of general relativity. Some scientists are lauding today as a landmark day in scientific history, and some are even saying that this could potentially change our understanding of astronomy altogether. But the real question that you may be asking is…well…”why does this matter to me? I’m not a scientist, so does this really affect me any? What are these waves anyway?”
And I’m glad you asked! So let’s talk about gravitational waves and you.
First, it helps to just generally understand Einstein’s theory of relativity. We all know it from pop culture somewhere or another, you know, good old E=mc2? Well let’s think about the universe simply. A very simple example is to imagine if the universe was like a blanket that you were holding between you and another person (not too tightly!). If you were going to drop a basketball on that blanket, what would happen? Well, it would make a basketball shaped pocket in the blanket where the basketball would sit! Now take this and apply it on a macro-scale. The universe is it’s own kind of blanket! It has a shape to it, and things are interconnected. Then place Earth (our big basketball) on the blanket/universe. Earth exists basically in a dent (or gravitational well).
Earth goes around the Sun sort of like a roulette ball (only in space), so it spins around the even bigger gravitational well created by the sun. So instead of thinking as gravity pulling you down, you have to completely shift your paradigm here. The universe is curved so that you (and your car, coffee, and computer) are all falling into the Earth (and into its gravitational well), even right now! Gravity is a shape of space and time together (time, in Einstein’s theory is the fourth dimension). Furthermore, there is no fixed reference point in the universe, everything is moving relatively to the next. Sort of like if you were walking on the train, and all of the people sitting there seem to be still, and the people on the platform seem to be moving? But in reality the people on the platform are stationary, the people sitting are moving with the train, and the walking person is moving inside of the moving train.
So what happens then if your little brother comes in and smacks the corner of the blanket? It may wiggle the basketball, and you’ll feel it in your hands. Well, that’s not unlike what we’ve observed! Catastrophic events caused by black holes and exploding stars can smack our proverbial blanket. We observed two black holes, which actually collided and made one black hole. As this happened, we detected the event using instruments on Earth. There were gravitational waves (i.e. your little brother smacking the blanket) that rippled through the universe – showing that there is a structure and a fabric underneath the universe (not a bunch of rocks spinning about willy-nilly). *Note, this event is not going to be as forceful as the example, it was an extremely subtle change.
How is this important then to me?
Well, Einstein made his theory about 100 years ago, and said that gravitational waves must exist, but said that there would be no way to ever detect them because they’re too weak. Well, thanks to the LIGO observatory, we did. The observatory is an “L” shape, with a central station, and two arms that extend 4 km. At the end of each arm is essentially a mirror, which reflects a laser which is shot from the central location. Theoretically both lasers bounce back and are recorded at the same time; and any other day that was the case. This time, the one laser was late – because the gravitational wave essentially stretched the distance the laser had to travel by distorting spacetime.
Some are speculating that with this knowledge and the products that will come from it, we may be able to see black holes, and with that…potentially back in time (as far back as the Big Bang they say). On top of that, we’re learning more and more every day about how gravity works – so we can understand the strings that hold the galaxy together. So back to the question of how it affects you. Nothing really has changed visibly; the universe is still doing the same that it has been! However, today has been the start of a potential scientific landslide; the things we may make of this might border on science fiction. But for a tangible take-away? Well, I guess you and I don’t have to worry about your fear of heights and falling anymore, just since technically we’re always falling! 🙂