It’s cold and rainy and foggy, not a bit what summer should look like. Perfect day for seeing a video on quasars, black holes and galaxy formation! One word: awesome.

Did you know:

1. A black hole is not empty space. It’s a huge amount of matter packed into such a small space, relatively speaking, that it results in a massive gravitational pull that gobbles up even light.
2. Einstein’s theory of general relativity predicted that a sufficiently compact mass will deform spacetime to form a black hole.
3. Quasars, the most luminous, ancient and energetic objects in our universe, are powered by the matter pouring into a black hole. They are some of the most distant objects to be observed, and looking at them is like looking into the past, the ‘early’ years of our universe.
   

   Black Hole Gobbles a Star. Credit: NASA.

4. Every galaxy has a supermassive black hole at its heart. Some have several black holes. In fact NASA has just discovered a large cluster of black holes in the centre of our nearest neighbor, Andromeda.
5. The size of the supermassive black hole is directly related to the size of the galaxy in which it is found. Its mass is about half percent of the mass of the entire galaxy.
6. Another strong correlation: the greater the speed of the stars in the outer parts of the galaxy, the greater the mass of the supermassive black hole. This is because the greater the speed of the outer stars, the more massive the black hole has to grow to ‘push’ them away.
7. Black holes were fundamental to the formation of galaxies. Even as black holes are the most destructive force in the universe, gobbling stars like there’s no tomorrow, so also have they been a force for creation. We wouldn’t be here if not for them.
8. At the heart of a black hole is its singularity, a place of infinite density where the laws of physics as we know them no longer hold. Time travel anyone?

In fact, wormholes (or the Einstein-Rosen bridge – one of the solutions of the equations of general relativity) have long been fondly regarded by science fiction enthusiasts as a short-cut through spacetime. Wormholes can best be thought of as a tunnel with a spinning black hole at one end and a white hole at the other. Fall down the black hole, emerge unscathed into a parallel universe!

Of course, actual traversable wormholes are possible only if exotic matter with negative energy density can be used to stabilize them. So don’t pack your bags just yet. But if traversable wormholes could be made to exist, they could be used to travel in time. (Something to do with  accelerating one end of the wormhole and relativistic time dilation – hey don’t ask me more, I snored my way through physics).

Even then, you couldn’t travel back in time further than when the wormhole was first converted into a time machine by accelerating one of its two mouths. Darn it. I’m never going to see dinosaurs, not unless they’re cloned Jurassic Park-style.

Further reading: Black Holes and Time Warps: Einstein’s Outrageous Legacy by Kip Thorne, physicist extraordinaire, who was was one of the first to research whether the laws of physics permit space and time to be multiply connected.