19 Questions and Answers About Black Holes


In the summer of 1990, I read British physicist Stephen Hawking's book A Short History of Time: From the Big Bang to Blackholes. I was a college student, and the book was probably the first popular science book I ever read. I was so interested in the book that I did not even get up and eat until I finished it. Although my initial excitement decreased over time, black holes continued to interest me in the following years.

In this article, I want to combine what I know about black holes with my research. I identified 19 questions people asked a lot. In this way, I hope to have answered questions about the subject.

What Is A Black Hole?

A black hole is a name given to very dense regions of space-time. Most of them were formed due to giant stars collapsing into themselves under the influence of gravity.

Black holes bend space-time so strongly that even light cannot escape it.

When Were Black Holes Discovered?

John Michell and Pierre-Simon Laplace first put forward gravitational fields that even light cannot escape in the 18th century. Karl Schwarzschild created the formulation of general relativity describing black holes in 1916.

David Finkelstein used this formulation to interpret black holes in 1958 as a region of space where nothing can escape.

Are Black Holes Black?

Because black holes bend and trap light beyond the boundary called the event horizon, we do not know their color.

Is the Black Hole Same as Dark Matter?

Blackhole and dark matter are different concepts. The common feature of the two is that they are invisible. Black holes refer to very dense regions of space-time.

Dark matter has been put forward to equalize the total amount of matter in the universe required by the universe's speed of expansion.

Can Every Object Turn Into a Black Hole?


A state of collapse into itself under gravity's influence is possible for stars ten times larger than The Sun. On the other hand, if the necessary force can be applied, there is a chance that each object will turn into a black hole.

In 1916, Karl Schwarzschild reached the formula r=2GM/c^2 due to the analysis of Einstein's general relativity equations. According to this formula, it is possible to calculate which radius an object will have due to turning into a black hole. In the formula, r refers to the radius of the black hole, G refers to the gravitational constant, M refers to the mass of the object in kilograms, c refers to the speed of light. According to the formula, if the Earth had turned into a black hole, its radius would have been 9 mm. If the Sun had turned into a black hole, its radius would have been about 3 km.

What Happens If We Get Closer To The Black Hole's Event Horizon?

The event horizon is the boundary region of a black hole where even light in space-time cannot escape. It is impossible to observe from the outside what is happening beyond the event horizon.

Since objects approaching the event horizon are also approaching the speed of light, time almost stops at the event horizon boundary. Besides, objects approaching the event horizon take a long thin form like spaghetti.

Do Black Holes Disappear?

Although black holes trap the substances they swallow, these mysterious structures emit some of their mass into space in Hawking radiation. Stephen Hawking discovered this phenomenon in 1974.

The evaporation process of black holes is predicted to continue for millions of years.

Can Black Holes Be Observed?

Black holes cannot be observed directly because they bend all particles, including light, beyond the event horizon.

On the other hand, as the bodies approaching the event horizon of black holes accelerate and heat up, the X-rays of these bodies shine, and black holes are thus indirectly observed.

Are Black Holes Likely to Engulf The Entire Universe?

Because the universe is expanding, it seems unlikely that black holes will swallow the universe. In this context, astronomers do not see such a risk for our solar system or Earth.

At the center of galaxies are giant black holes. Because our solar system is far from the center of our galaxy, there is no risk of being swallowed up by the black hole at the center of our galaxy.

Are Black Holes Dangerous?

Black holes are one of the most dangerous bodies in the universe because of their extraordinary gravitational force.

On the other hand, they are not a danger to us unless we approach them in a way similar to wild animals in a cage.

How Many Black Hole Types Are There?

According to NASA, it is possible to mention three types of black holes.

Black Holes, thought to have formed just after the Big Bang, are thought to be between an atom's size and the size of a mountain.

Black holes formed as a result of stars more than ten times larger than the Sun collapsing into themselves constitute the second group.

Gaint black holes formed at the center of galaxies constitute the third type. These have a mass at least 1 million times larger than The Sun.

Where Is The Closest Black Hole To Earth?

According to detailed research conducted in 2014, the V4641 Sagitarii black hole was estimated to be 20,000 light-years from Earth.

What About Black Hole's Shapes? Do They Move?

Black holes are thought to be three-dimensional and sphere-shaped.

Some of the black holes revolve around themselves.

Do The Known Rules of Physics Apply Inside Black Holes?

Inside black holes, the equations of physics that define space and time are collapsing. We can argue that different rules work within these bodies compared to the general universe in this context.

A gravitational singularity forms at the center of the black hole. The density, gravitational force, and bending of space reach infinity, and the mass is compressed into a point dimension.

What Happens If Two Black Holes Approach Each Other and Collide?


A supernova explosion can illuminate an entire galaxy. The collision of two black holes will have millions of times more impact than a supernova explosion.

When two black holes approach each other, they begin to spin around each other. As this event severely bends the space surrounding black holes, all celestial bodies in the immediate vicinity disappear. As black holes approach each other, the geometry of space begins to deteriorate. As they approach each other, they spin faster and emit gravitational waves. Eventually, they merge and form a giant mass black hole. It is such a terrible event that it could destroy an entire galaxy.

Dr. Weiss, Dr. Thorne, and Dr. Barish achieved these results by analyzing LIGO observatory data that measured gravitational waves generated by the collision of two black holes and was awarded the Nobel Prize in Physics in 2017. Thus, a concept put forward by Einstein was further confirmed.

Have Black Holes Been Observed To Swallow Any Objects?

In recent years, Spanish scientists have observed for the first time the explosion that occurs when a black hole swallows a star during the intertwining of two galaxies 150 million light-years from Earth, the supermassive black hole at the center of a galaxy collided with a star twice the size of the Sun.

The data generated as a result of the collision confirmed the mathematical concepts put forward in this regard.

How Do Black Holes Affect The Image Of Space?

As light bends as it passes around, black holes distort the image of distant galaxies.

Can Black Holes Help Explain the Formation of the Universe?

A similarity is established between the singularity formed in the center of black holes and the singularity that existed before the Big Bang.

Therefore, it is believed that research on black holes will help understand the dynamics that led to the Big Bang.

Can Black Holes Be Doors to Other Universes?

In 2017, physicist Nikodem Poplawski, working at Indiana University, developed new mathematical models for the path followed by substances falling at the center of black holes. According to Poplawski, the matter accumulated at the center of the black hole is transferred to another universe, rather than forming a singularity, forming the raw material for new galaxies, stars and planets there. This flow of matter is happening through a kind of wormhole called a white hole.

Poplawski cannot yet explain exactly how parallel Inter-universes exchange of matter through black holes occurs.

Thanks for reading.



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