What are the After-effects of a Black Hole?

There are certain large objects in the universe such as stars and galaxies that produce black holes after intense gravitational collapse. Not even light entering such a region of space can escape due to the extremely strong gravitational field. These are black voids that are present in the space.

According to Albert Einstein, massive stars that are more than twice the mass of the sun, shrink continuously by emitting heat. This is the process taking place in dark stars.

An easy way to understand this concept is through the concept of escape velocity which, most of us have encountered in high school physics. In simple words, it means, how fast you have to go to escape the gravitational field of an object.

For example, the escape velocity of earth is 11.2 km/s, which means that if your velocity is equal to or greater than the escape velocity (Vesp) of the earth from which you are trying to escape, you never come back and go all the way to infinity. Black holes have an escape velocity, greater than or equal to the speed of light (speed of light = 3 × 108 m/s).

We know that if Vesp = speed of light, then light won't escape from the object as it will be dragged back by the gravitational pull of the black star because of which, we won't be able to see it. Though such a region of space cannot be seen directly, we infer its presence by analyzing the motion and heat of the objects circulating around it.

The black holes with solar mass, absorb the particles, more than they emit, and their temperature will be lesser than the cosmic microwave radiations around them. There are some small regions of space that were formed due to density fluctuations of the universe at the beginning.

These emit more radiations and absorb less particles due to which their temperature is very high. When they emit more radiations, their size decreases and temperature increases. Different species of particles get emitted from the void due to highly increasing temperature and reducing mass.

The intensity of these particles that are emitted are so great that such a region of space radiates all the particles, which cause an explosion of 1035 ergs, in terms of energy. The rate of emission of radiation from such a region takes place at a steady rate similar to the rate of thermal emission from a human body.

The event horizon (boundary within which gravity of such a region of space is tremendous) of such a region can never decrease, but, when two of these collide and fuse together, the area of the event horizon thus formed, will be more than the sum of the event horizons of the individual ones.

Supermassive black holes are the most terrifying and destructive elements in the universe and its impact on the nearby objects like planets, stars, etc., is huge and unimaginable. It's more or less like a science fiction, rather than reality. These interested our astronomers and they started to search for them.

They found these in whichever galaxy they turned their telescope to. Even at the center of our milky way galaxy, there is such a region of space of apocalyptic proportions, which is 3 billion times bigger than the size of our sun.

The one in our galaxy is 27,000 light years away from our earth and it contains the mass of 4 million suns crushed down into a single point by its gravity. The closer you get, the stronger the gravity is.

Scientists have found that the reactions of gases, particles and radiations that take place inside these regions of spacetime might initiate the growth of stars, planets and even life in the universe.

Physicist John Dubinski, however, after studying the effects of these giant holes, believes that in 3 million years, our earth might colloid with our neighbor galaxy 'Andromeda', which will force our earth out of the orbit, and that we will be pulled in by the maelstrom of the supermassive black hole!

Such a region of space has a dramatic effect on time, slowing it down far more than anything else in the galaxy. That makes it a natural time machine! If we could just imagine, how a spaceship might someday be able to take advantage of this spectacular phenomenon. We all are fascinated by the concept of 'time machine'.

To analyze this, and to take advantage of this natural time machine, a spaceship was sent by a space agency, to orbit around it with a circle of 30 million miles in diameter. The spaceship was made to orbit around a safe boundary, and with a certain speed, that would escape it from not getting sucked in by the deadly massive black void in the space.

The space agency that took control of the spaceship, was far away from the region and they observed that, each full orbit took 16 minutes. But for the brave people on board, close to this region of space, time would be slowed down by half.

For every 16 minutes orbit, they had only experienced 8 minutes of time. Imagine, they circle it for 5 years, but 10 years would pass somewhere else! When the crew of the spacecraft would return to the future earth, they would have made a journey not only in space, but in time.

❖The sound waves due to the explosion of such a region of space can inhibit the growth of the stars, that are 300,000 light years away (1 light year = 9,460,730,472,580.8 km).

❖Scientists, while studying A2104 galaxy, using the Chandra X-ray Observatory, found many powerful sources of X-ray radiations from such a region of space in areas that were devoid of gas.

❖The X-ray jets or quasar jets from it, gave scientists some information about the conditions that prevailed in the early universe.

❖According to Dr. Michio Kaku, a physics professor from New York University, when you shoot a nuclear weapon into the heart of such a region in space, it would just be a pinprick effect, as compared to the gravitational effect of the black hole.

"The most spectacular aspect of our 16-year study, is that it has delivered what is now considered to be the best empirical evidence that supermassive black holes do exist" -Professor Reinhard Genzel, University of California, Berkeley, explained this and also Head of the research team, which confirmed that there is one in the center of our milky way galaxy.

Our universe is endless and exploring it every time changes the views and ideas of scientists like the way, black holes did. The universe is still a mysterious wonder. Studying about them is one of the interesting things in astronomy because of its obscure and powerful nature. Even today, such a region of space still remains a mystery to scientists.