Ghosts in the sky

Date: 23 March 2018

Warm and a humid evening in the coastal town of Chiplun in the mighty Sahyadri range surrounded by the Himalayan peaks covered with dense forests, and rivers cutting deep through the valleys to make the best of the grand old Western Ghats. Riding a bike through the mountains with the clouds clashing across my face, the smell of fresh soil and the road hugging the mountain side, going through the tunnels, getting drenched in rain is a rejoice. Evening quickly turned into a pitch dark night with clear skies. I was standing with my brother in a middle of a forest on a mountain top with no human activity and teeming with wildlife, owls hooting at us, no torches, no fire. I did not flip and was calm enough to brave through it. I happen to look above me and saw something that made my senses flip, my heart racing, goosebumps all over my body, my mind trying to comprehend to what I saw.

Billions of stars of the Milky Way galaxy above me along with the stars and galaxies far, far beyond. Imagine yourself in that situation.  It was not a 5 star hotel view, it was a 5 billion star hotel view. I stood there dumb founded. My brother has an excruciating curiosity about the universe and the mysteries that contain in it. Suddenly, I heard  a loud voice asking me “What’s a Black Hole !?, What’s a Black Hole !?”, it was my brother asking me on top of his voice, disturbing the wildlife. I was lost in my own world.

I saw something like this.

So, what are black holes ?

Black holes are one of the strangest things in existence, they don’t seem to make any sense at all. Where do they come from and what happens when you fall into one ?

Let the journey begin.

Stars are incredibly massive collections of mostly hydrogen atoms that collapsed from enormous gas clouds under their own gravity. In their core, nuclear fusion crushes hydrogen atoms into helium releasing a tremendous amount of energy. As long as there is fusion in the core, the star remains stable enough. But for stars with way more mass than our own sun the heat and pressure at the core allow them to fuse heavier elements until they reach iron.

When the iron builds up at the center of the star until a critical amount, the core collapses under its own enormous weight. Within a fraction of second, the star implodes, moving at about the quarter of the speed of light, feeding more mass into the core. It is at this very moment that all the heavier elements in the universe are created as a star dies in a supernova explosion. This produces either a neutron star or a black hole.

Exhilarating stuff.

So, where can we find a black hole ?

There are two kinds of black holes out there: the super massive black holes at the heart of every galaxy, and the stellar mass black holes formed when massive stars die in a supernova.

The super massive ones are relatively straightforward. There’s one at the heart of pretty much every single galaxy in the Universe. One in the middle of the Milky Way, located about 27,000 light-years away from where you stay. One in Andromeda 2.5 million light years away, and so on.

No problem, the super massive ones are really far away, no threat to us.

The stellar mass ones might be more of a problem.

No human has ever seen a black hole. But imagine this picture for your understanding.

Yes, I like Interstellar.

When you look at the black hole, what you’d really be seeing is the event horizon. So, we just see a black sphere reflecting nothing. The center part of the black hole is called the singularity. No one knows what it is. A singularity may be infinitely dense, meaning all its mass is concentrated into a single point in space with no surface or volume. It is like “Divide by zero error”. The gravity is so strong that even light cannot escape the pull of a black hole. Because no light can get out, people can’t see black holes. They are invisible. Ghosts in space.

Black holes can be big or small. Scientists think the smallest black holes are as small as just one atom. These black holes are very tiny but have the mass of a large mountain. Another kind of black hole is called “stellar”. Its mass can be up to 20 times more than the mass of the sun. There may be many, many stellar mass black holes in Earth’s galaxy. The largest black holes are called “super massive.” These black holes have masses that are more than 1 million suns together. Scientists have found proof that every large galaxy contains a super massive black hole at its center. The super massive black hole at the center of the Milky Way galaxy is called “Sagittarius A”. It has a mass equal to about 4 million suns and would fit inside a very large ball that could hold a few million Earths.

So, what happens if you fall into a black hole ?

The experience of time is different around black holes, from the outside you seen to slow down as you approach the event horizon, so time passes slower for you. At some point, you would appear to freeze in time, slowly turn red and then disappear. You become a ghost here. He he he. From your perspective, you see the universe fast forward, kind of like seeing into the future. No one knows what happens next – may be you die with your cells gets torn apart, your organs stretch until they break, you break open your skull and blood will ooze out of your skin pores until you are a hot stream of plasma one atom wide. Puke, Nothing is pleasant about it, right ?

Black holes do not stay forever, eventually they evaporate through a process called “Hawking radiation”. The biggest black holes may take a googol years to evaporate. Extremely slow. Wicked sounding math numbers.

Tribute to a legend. RIP Sir. Inspirational.

The hawking radiation is already a different topic. Let’s not kill any birds going for this.

So, what if a sun is replaced by a black hole of the same size ?

Nothing would happen to the solar system and its planets. But of course we would freeze to death due to the lack of heat and sunlight.

Then my brother asked me an extremely good question. Are black holes ghosts?

I said “No not in the human kind, look above to see the sky full of them. Every star is as big and bright as our own. Just image how far you have to move the sun to appear it look small and faint enough to make it a star. The light from the star travels very fast but not infinitely fast. It takes time for their light to reach us. The nearest ones takes 4 years, some takes decades, centuries and some are so far away that it takes eons for the light to reach us. By the time the light of some stars get to us they are already dead. For those stars we see only their ghosts, we see only their light but their bodies perished long ago. I am one of the very few and esteemed people who has seen further back in time than anyone else, millions of years into the past.”

The telescope is a time machine. We cannot look out into space without looking back in time.

Now coming to the most interesting project that mankind has taken up. To point the largest array of telescopes at a super massive black hole at the center of the Milky Way galaxy – Sagittarius A* to take a picture of it.

What!!!!!!!!!!!!!!! Shocking right ?

Yes, the first picture of a black hole. Yes, I would be joyed to look at the picture, like looking at my baby (future of course).

I know. Seems freaky a see an actual ghost.

In the next couple of years, mankind will have seen the first black hole ever.

My reaction was like :-O

An Earth sized telescope and a clever algorithm that puts together the final picture. The final frontier is everywhere.

A lot to explain on this topic again. Let’s not kill some cats.

You know that saying, “keep your friends close, but keep your enemies closer?” That advice needs to go right out the window and down the gutter when we’re talking black holes. They’re the worst enemies you could have and you want them as far away as possible.

This is not the end of the story. There are loads more interesting ideas about black holes. I have not discussed about the space time curvature, information paradox, energy paradox, bending of light, time paradox, theory of relativity, quantum physics, LIGO, parallel universes or multiverse, white holes, so many things are required to understand a black hole. Black hole is like girlfriend, does not cooperate in understanding them.

The black holes are not entitled to share their secrets with us. No one knows the number of black holes in the sea of the cosmic arena. We are just a speck of dust suspended in the sun beam.

After I finished explaining my brother about the black holes, suddenly, I felt a lot smaller than the rest of the Universe.

I think I am going to write another post on black holes soon. So much to learn, so much to learn, so much to learn …. I know nothing.

So, do ghosts exists ?

Yes, they do. When you are in the dark and afraid of the ghosts, remember that the black holes are the real ghosts.

The view of the stars on a mountain top in the Western Ghats on a clear moonless night on planet Earth is nothing compared to what is actually out there. A simple act of star gazing has bring in some profound influence about life in me. I would love to go star gazing in Ladakh, Atacama Desert, Antarctica and the Northern lights of the Arctic Tundra with a bonfire and some deep talking with my “special one”.

To ghosts,

Vishal

Just a normal guy.

(My brother is Karan Velhal. Coder. Curious. Fun loving. I owe you a big one buddy.)