Whispers from the Abyss : The Dark Mysteries of Black Holes

(This post contains all my knowledge about black holes that I have come to learn recently)

1.0- What is a Black Hole?

Blackholes are maybe the most elusive objects in the entire universe. They are extremely dense, massive objects that have such a strong gravitational attraction, not even light can escape their pull. Our galaxy alone could contain over 100 million individual black holes, but since they emit no light, they are extremely hard to find unless they are eating.

1.1 – How are Black Holes formed?

Blackholes are formed when massive stars collapse under their own gravity at the end of their life cycle creating a singularity, a point of infinite density at the center of a blackhole.

1.2 – Sagittarius A*

At the center of our own galaxy lies a supermassive blackholes named Sagittarius A*. This Blackhole has a mass of 4.3 million times more than our sun and is surrounded by a disc of gas and dust spiraling into its gravitational embrace.

1.3- Gravitational Waves of Black Holes

When black holes collide with one another, they send literal ripples throughout the fabric of space time at the speed of light. These ripples squeeze and stretch everything in their path. Similar to the ripples on a lake. Now, Einstein predicted that these ripples must exist if his theory of general relativity were to be correct. But it wasn’t until 2015 that we finally detected one for the first time. Scientists use an instrument called the Laser Interferometer Gravitational-Wave Observatory (LIGO). A laser beam is split down to four-kilometer-long arms with mirrors at the end that reflect the lasers back and forth. Now, as the gravitational wave passes through the earth, the length of each arm is changed ever so slightly, which they were able to detect using this method.

1.4 – How do we image Blackholes?

Supermassive blackholes that live in the center of most, if not all galaxies consume an unbelievable amount of matter, forming the brightly glowing accretion disks you would see in movies like Interstellar. Now, while you can’t see the actual blackhole itself, you can see the event horizon, the point of no return where light is sucked inside the black hole. Despite how far away they are and how impossibly hard they are to find; scientists were actually able to take pictures of two using a telescope the size of earth. By using individual telescopes placed all around the globe, you can create an array of telescopes that could theoretically image the black holes. And so, they set two targets, the closest supermassive blackhole to us, Sagittarius A* and the supermassive blackhole in the galaxy M87, one the most massive blackholes we know of. Sagittarius A* is actually our black hole that lives in the center of the Milky Way galaxy. It is just 26,000 light years away from you right now. M87 on the other hand is located 53 million light years away.

1.5 – The Biggest Black hole

In the heart of a galaxy 8.5 billion light years away, lies the largest black hole ever discovered. And this is thing is terrifying. Phoenix A* is the black hole, and it’s 100 billion times larger than our sun. In fact, this black hole is so big that it’s actually bigger than some entire galaxies. The diameter of the event horizon for this black hole is 100 times the distance between the sun and Pluto. That means that if you were traveling in a spaceship at the speed of light, it would still take you 71 days to complete one full loop of the black hole.