BLACK HOLE: A HUNGRY MONSTER

The most important headline in the news is the discovery of a black hole at the center of the Milky Way Galaxy.

The concept of black holes can be approached both theologically and scientifically. The advancement of science and technology has helped us learn more about these cosmic giants — but wait, are they really gentle???

Many people, especially the younger generation, consider black holes to be monstrous entities that engulf everything that comes near their field of influence. According to them, black holes are horrific and terrifying. The truth isn’t too far from this, but did you know that black holes play a crucial role in the functioning of our Universe? In fact, everything in the Universe has both positive and negative aspects associated with it.

NASA’s modern telescopes have captured an image of this black hole at the center of the Milky Way Galaxy — you can find the image below...

                                            

Figure 1: Sagittarius A*

''In space no one can hear you scream; and in a black hole no one can see you disappear''

With this insightful quote by Professor Stephen Hawking, today, let us discuss about black holes, in particular about Sagittarius A*, Milky Way's own Black Hole!

HOW ARE BLACK HOLES FORMED?

We all know about stars — those twinkling objects we see in the night sky. Stars live for millions of years. Different stars have different lifespans, and the lifespan of a star is determined by its size. Take our Sun, for example — it is a star that can live for about 10 billion years. This means our Sun will die in roughly, 5 billion years.

Black holes are formed from such dying stars. But wait — can every star become a black hole?

Black holes are formed when the cores of massive stars collapse or explode. These stars end their lives in a supernova explosion. A supernova explosion is extremely powerful — the burst of light is so bright that it can be seen across the Universe.

As already mentioned, the supernova explosion is so powerful that most of the star’s material gets blown away, leaving behind a black hole. It’s also important to note that supernova explosions are rare events.

                

Figure 2: The bright white spot that you see in this picture is a real supernova explosion

HOW IS A BLACK HOLE?

''What happens in a black hole, stays in a black hole''

A black hole has an extremely high concentration of mass (or matter), resulting in an exceptionally strong gravitational field. Due to this intense gravity, nothing — not even light — can escape from the clutches of a black hole.

The smallest known black holes in the Universe have at least three times the mass of the Sun — that’s approximately 5.9673×10³⁴ kg.

Sagittarius A*, the supermassive black hole at the center of the Milky Way Galaxy, has a mass about 4 million times that of our Sun. This translates to roughly 7.9564×10⁴⁴ kg! According to Newton’s Universal Law of Gravitation, the greater the mass, the stronger the gravitational force. You can’t even begin to imagine the gravitational field that this monster black hole possesses…

All the familiar concepts of space and time that you learn in school — the ones that work just fine elsewhere in the Universe — completely break down inside, or even near, a black hole.

                                                        

Figure 3: Albert Einstein

According to Einstein's Theory of General Relativity, nothing can escape from a black hole. The Theory of Relativity is one of the few theories which can explain most of the macroscopic phenomena and is used widely in understanding more about black holes...

BLACK HOLES AND TIME

Time ticks slower near a black hole. This is because of the immense gravitational field, which warps spacetime so strongly that the flow of time itself slows down near the black hole’s event horizon. This phenomenon, known as gravitational time dilation, was predicted by Einstein’s General Theory of Relativity and has been confirmed through observations and experiments. In fact, this very effect is what makes black holes not just cosmic monsters, but also natural time machines — at least, into the future.

This leads to an intriguing consequence — aging slows down near a black hole. If a person could somehow hover just outside the event horizon, they would age much slower compared to someone far away. In fact, a few hours near the black hole could mean decades have passed elsewhere in the Universe. This mind-bending effect was beautifully portrayed in the movie Interstellar, where time on a planet near a black hole passed at a fraction of the rate experienced by those farther away.

However, this concept of "immortality" near a black hole is only partly true. While time slows down drastically near the event horizon, falling inside the black hole is a completely different story. Once you cross the event horizon, physics (as we understand it) breaks down. Space and time essentially swap roles, forcing you to move inevitably toward the singularity—a point of infinite density at the very center. This journey is one-way and ends in spaghettification, where the extreme gravity stretches your body into thin strands of atoms.

Interestingly, this concept of time distortion isn’t limited to black holes. Even the GPS satellites orbiting Earth experience a tiny version of gravitational time dilation—their clocks tick slightly faster than clocks on Earth’s surface because they are farther from Earth’s gravity well. This is a small-scale reminder of the cosmic time-bending power black holes possess.

In short, black holes are not just cosmic vacuum cleaners—they are portals to extreme physics, where time slows, space curves, and the laws of nature are pushed to their absolute limits. They are the perfect reminder that in this vast, mysterious Universe, reality is often far stranger than fiction.

HOW BLACK HOLES DIE OUT?

Black holes are living systems, they become bigger and bigger by engulfing matter which gets trapped in its strong gravitational field. 

                                                              

Figure 4: Stephen Hawking

The seminal contributions of Professor Stephen Hawking played a major role in helping us understand black holes better. It was Stephen Hawking who proposed that black holes do not last forever. But why is that?

The answer lies in a concept called Hawking radiation.

Hawking radiation refers to electromagnetic radiation emitted by black holes. This strange phenomenon arises from quantum effects near the event horizon — the boundary of the black hole. When a black hole emits Hawking radiation, it gradually loses mass along with rotational energy. Over extremely long periods of time, this continuous loss of energy could lead to a theoretical process known as black hole evaporation, where the black hole could shrink and eventually vanish entirely.

WHAT HAPPENS WHEN TWO BLACK HOLES COLLIDE?

                                                           

Figure 5: Binary black holes

When a black hole gets caught in the gravitational field of another nearby black hole, the two become gravitationally bound, meaning they are unable to escape each other’s pull. This interaction eventually leads to the merger of both black holes, forming a single, larger black hole with an immense gravitational field. The resulting black hole is extremely energetic and often violent, releasing enormous bursts of gravitational waves—ripples in spacetime caused by the collision.

Such a system of two black holes orbiting close to each other is called a binary black hole system.

The following set of images illustrates the different stages involved in the collision and merger of two black holes, capturing one of the most powerful events in the Universe.

                                                               

(1)

                                                    

(2)

                                                   

(3)

 

                                                   

(4)

                                                  

(5)

                                                    
Figure 6: Series of images (1) to (5) depicting the collision of two black holes

Albert Einstein once said,

''Black holes are where God divided by zero''

This is perhaps one of the most profound and imaginative descriptions of a black hole. This quote, attributed to one of history’s greatest scientists, highlights the uniqueness, extremity, and mystery surrounding these cosmic monsters.

REFERENCES:

1. All the images given in this blog were taken directly from Wikimedia Commons.

2. The information regarding some values and some concepts were taken from websites, mainly from jpl.nasa.gov

*All the media published in this blog belongs to their original creators and 'Knowledge Through Science' does not claim any right over it.