The scientific community announced yesterday, June 15, that gravitational waves have been detected for only the second time ever. Gravitational waves are basically ripples in space and time that travel outward from their source, for example two black holes smashing together–just like the ripples that move outward when you throw a stone into a pond. But what exactly do I mean by ripples of space and time?
The theory of relativity.
When you think of gravity, you probably think of what you learned in high school physics: anything with mass has a gravitational pull, smaller things are pulled toward bigger things, and that’s why things (including us) fall to Earth. Gravity is a force that pulls things toward each other.
In 1915, Albert Einstein published his general theory of relativity, providing physicists (and the rest of us) a modern theory of gravitation. Einstein described gravity as a property of both space and time, where the two are intricately woven together, and formed predictions related to this. As time passed, scientists confirmed his predictions over and over again. But it was only in the past year that scientists confirmed–finally!–his prediction of gravitational waves. We just couldn’t detect them until late 2015, even though scientists have literally been trying for decades.
The first detection (announced this past February) recorded the collision of two massive black holes that occurred about a billion years ago. When these black holes collided, an intense amount of energy was was sent outward in gravitational waves. This collision literally bent and changed space and time — ripples. These ripples were recorded as vibrations, which we can actually hear!
And now, for the second time — scientists have detected another collision! Two black holes collided together and formed a black hole 21 times the size of the sun. THAT.IS.MASSIVE.
What’s a black hole?
A black hole is an area of space with so much gravity that nothing — not even light — can escape its pull. We unfortunately don’t know much about black holes. We can’t even see them!
Gravitational waves now provide astronomers with data that can be used to learn more about black holes and, more generally, gravity itself.
Why are astronomers so excited?
When we first started exploring the universe, scientists used their eyes–and therefore, light–to see space through telescopes. This pretty much limited our knowledge of space to what we could see. Slowly, we started learning more about the universe with different technologies, like x-ray and radio wave observations. With gravitational wave detection, it is pretty likely that we’ll make a lot of new, really awesome discoveries. Who knows what is out there, so far unobserved by humans, that gravitational waves can lead us to?