Black Holes

I was snooping around the house to look for some interesting books to read. Well, I got my wish. Found  a book near the bag of my brother’s which was titled “Stephen Hawking’s Universe”. I thought: Hey! Why not? It’s been awhile since I last read about Physics anyway…” so I took it, flipped to the content page, nodded and went back to my room.

I decided to start off with Black Holes (thus the post). Black holes are truly fascinating don’t you think? One can’t see them but we are all 99.999999999999999999999999999999999999999999999999999% certain they exist! That’s truly intriguing. It totally throws away the literal meaning of ‘Seeing is Believing’. (just a warning, this post might be a bit on the dry side for those who do not understand or like Physics/Astrology)

So what are Black Holes? Okay simply put they are rips in the fabric of space and time so dense and distorted by unimaginable gravitational forces that for years physicists believed nothing could escape from one, including light. Hence, by definition, they are deemed as invisible. Well which is quite true, one does need light in order to see things. Nobody can ever see one, nor will ever see one, not even if he or she uses the most powerful telescope in the entire universe. (Try switching off the lights, boarding up your windows and taping up the gap between the door and the floor. I think it’s a good enough simulation)

As Stephen Hawking said, “Within black holes, space and time we we normally perceive them come to an end.” Exactly how or what the difference is I have no idea and I sure do not want to try. Chances are if I enter a black hole, I don’t think I’d be able to tell anyone about it =D The gravitational force in a black hole is so strong that if let us say I would throw a sphere towards the black hole (assuming i can see it) you would see the sphere being stretched into an oval-like shape when it reaches the edge. After that, poof! It disappears ^^ That is how strong the gravitational force of a black hole is. It basically sucks up everything.

In my JC days, I had one amusing lecturer who used to go: “Gravity sucks” yeah well it’s true. It sucks things in literally and figuratively because he knows some of us dread that topic. Talk about your typical intended pun XD Well, your dear friend black hole sucks in anything and everything (something along the lines of being like a vacuum). There is no way of escaping a black hole (Don’t some of us wish that we could throw our homework in? =D Jkjk)

Stephen Hawkings and other theorists are convinced that the long-sought unifying concept in Physics (which explains the central interaction of the universe), lies at the periphery of black holes or similar peculiar constructions arising at one point of another in the evolution of cosmos.” ~ John Boslough, author of Stephen Hawking’s Universe

So how are black holes formed in the first place? Well, they are actually result from the death of stars (think astronomy not entertainment) Physicists say that a black hole is “described as the final stage in the death of a star before the point of singularity is reached.” This is how a break with our usual perception of space-time is created. That point of singularity is masked. (Gravitational Singularity: a point in spacetime in which gravitational forces cause matter to have an infinite density and zero volume ~wiki)

Let us look at the sun. There are two forces contending against each other. It was therorized that gravity will eventually gain the upper-hand as the sun’s nuclear fuel is spent and will then begin to collapse. When sufficient condensation has occurred, the sun becomes a ‘white dwarf’ – basically a ball of atomic nuclei + loose electrons. For the sun, this white dwarf would only be about 4x as large as the earth (minute in cosmic terms)

The mass, however, would remain as it ias and hence the gravitational pull on the surface atomic particles would increase drastically in strength. (think 380 mps to 2.1K mps) The collapse can continue but in order to reach the point whereby it literally annihilates itself, the star has to be really humongous. The sun, in which case, has only an initial mass of average value. It is theorized by Physicists that the sun will no longer continue to collapse once it turns into a white dwarf. This is because a law of physics called exclusion principle intervenes

The law of exclusion principle states that two electrons cannot occupy the same energy space, meaning there is a limit to how tightly matter can be packed together. By ordinary standards the limit is high and at the white dwarf stage, a thimbleful of the sun would weigh tons. Chances of an electron meeting another electron in the same energy space would jump.

If, however, the star has an original mass which is much greater (app. >1.4x tt of the sun) gravitation overpowers the law of exclusion principle. It thus passes through the ‘white dwarf’ stage and continues down the path of gravitational collapse: being drawn down further and breaking atomic nuclei apart, even destroying atoms. It is now what one would call a ‘neutron star’

This ‘neutron star’ is a (heavy) mass of neutrons and is no more than a few miles across. At the surface, escape velocity would be 120k mps (compared to the earth which is only about 7mps without air resistance). We should wish any star which has a mass of about 3.6x or more that of the sun because it will continue contracting at the neutron star stage. Gravity literally draws the star down into itself and that it becomes ‘a victim of its own weight’. It then reaches a point so far in deep that escape velocity becomes 186,282 mps aka the speed of light o.o At that instant if you watch the star, it is nothing more than a dim glow which would flicker out pretty soon.

Light is finally claimed by gravity. The star is now a black hole and is utterly invisible to the naked eye and even the most powerful telescope that one can possibly find. Of course, it will remain so for an extremely long time (i’m thinking aeons)

So if it is invisible? How do Physicists know and why do they agree in general that Black holes do exist? Both astrophysicists and even theoretical physicists would like to take a look. Hawkings himself, however, has become convinced, along with some other physicists that one has actually been found. The constellation of Cygnus.

There are stars which travel in pairs. (binaries) These stars orbit around a common center of gravity. It is reasoned by Astronomers that if one of the stars die and turns into a black hole, that now-invisible-black-star would still have a gravitational hold on its..um…well…lifemate? partner? mate? Oh well. Moving on, Hawking is certain that there is such a thing. Astronomers actually discovered it. The constellation of Cygnus is 6k light-years from Earth. The one which is visible is blue and it looks as if someone invisible is pulling it from one side, hence the shape of an egg.

cygnus
Left: Cygnus Constellation; Right: Cygnus X-1

Discovered in 1973, Cygnus X-1, the apparent black hole in the binary system, threw everyone into a state of excitement. Think about a kid who has just received his first game console and multiply that excitement level by a hundred. It probably barely reaches the same level XD

Just a little bite of history, there was a mini bet going on between Hawking and Kip Thorne (a friend of Hawking who was a respected theorist at the California Institute of Technology) about the ancestry of the mysterious object in Cygnus X-1. The interesting thing was that Hawking actually bet against it. Of course, Hawking himself was fairly confident and certain that it is a black hole.

“If it isn’t a black hole, it really has to be something exotic.”~ Stephen Hawkings

More than one might have been discovered by Astronomers. Another black hole announced by a team of Canadians and Americans in 1983 was discovered outside our own galaxy. This little baby apparently emits powerful X-rays and that was how it was found. In the Large Magellanic Cloud, a satellite galaxy of the Milky Way visible only in the Southern Hemisphere.

This black hole’s distance from earth is estimated to be 180k light-years, has the weight of about 10 suns with its distance from its binary mate a mere 11 mil miles. These were estimated whilst using a 158-inch telescope at the Inter-American Observatory at Cerro Tololo, Chile.

In the 1970s, Black holes started to become a cultural phenomenon. They were a common topic on talk shows and the subject of gags and jokes (I personally do not think it will be funny if you actually get dumped into one).

With the existence of a black hole, it is deemed to be a strange resident of the universe, perpetually straining the laws of physics. And what is stopping it from further collapsing onto itself? To the point of singularity, an infinite density, and perhaps causing another phenomenon similar to the Big Bang? If a star can collapse onto itself, why not the whole universe?

I thus end my very very very long post on Black Holes. Hope you enjoyed it =) Please feel free to comment on any mistakes that i made.

P.S. This whole post is inspired from and credited to: Stephen Hawking’s Universe by John Boslough.

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