LIGO

A gravitational wave, created during the merger of two black holes, passes through the Milky Way galaxy, our Solar system, the Earth. And, at about 3:30 PM IST on 14 September 2015, it passes through you and me and our cat, travelling at the speed of light. 


Not only could we detect it, but we can hear it… A 'sound' that originated 1.3 freaking billion years ago. 
Science is sexy.

I have been reading about gravitational waves in particular, and waves in general, and here's something that at least I wasn't aware earlier. 
We have seen tides rising up on a beach. In reality, a tidal 'wave' is nothing but a mass of water held in its place by the gravity of Moon (or Sun). The 'wave' stands still, and it's we standing on the ground are going towards it due to Earth's rotation.

People are mixing up ‘gravity waves’ and ‘gravitational waves’, assuming both to be the same. In fact, they aren’t. 
Gravity waves are ripples caused by gravity and are observed in a planetary environment, for example, atmosphere and water bodies. They are easy to observe... Just visit a nearby beach and observe the tides.
Gravitational waves, on the other hand, are ripples in gravity itself (or more precisely, ripples in the space-time). They propagate through *everything* and are very difficult to observe. 
The LIGO team observed gravitational waves.

The more I read about the LIGO experiment, the more intriguing it becomes. Consider the facts…
A pair of black holes; one 36 times massive as Sun, the other 29 times, are circling each other at 250 times a SECOND.
1.2 BILLION years ago, they merged, forming a black hole with mass 62 times as the Sun. The 3 solar masses lost in the process sent a ripple through space-time, in the form of gravitation waves.
The wave reached Earth on 14 September 2015. The impact it had: Displacing a 4-kilometer long mirror by 10^-18 meters, which is one-thousandth of the diameter of a PROTON.

And if you think THIS is amazing, consider that Einstein predicted this a HUNDRED years ago.