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# All Interesting Facts About Black Holes and White Holes

Because we don’t wanna sound racist, we are presenting some unknown and interesting facts about both- the black holes and the white holes.

What exactly is a Black Hole?
Simply put, a black hole is incredibly dense region of space that nothing can escape front its surface, not even light. The boundary of the region is called event horizon. It is a point where the escape velocity from the gravitational field is equal to the speed of light.

What is White Hole?
A white hole is exactly opposite of a black hole. You can never escape a black hole, whereas white hole is a hypothetical region where you can’t enter from outside, in other words, you can leave but can never go back. Just like black holes, white holes have properties like charge, mass, momentum etc.

Let’s elaborate both of them and find out some mind-bending facts based on scientific theories.

## Black Hole

### 1. Black Hole Affects Time

The clocks run really slow near black holes as compared on earth, due to the massive gravitational force.
This all depends on the curvature of spacetime around a black hole. A beam light has to cover a greater distance near a black hole. However, to an observer in that extreme gravitational field, light must appear to always be 299792458 m/s, time has to slow for that individual (observer) as compared to someone outside the gravitational pull.

### 2. They are Incredibly Big

Of course Black hole is a giant structure but how big it is?
The mass of a black hole is directly proportional to the size of the event horizon (also known as Schwarzschild radius). Scientists have discovered event horizon ranging from 6 miles to the size of our solar system.

The Schwarzschild radius of the Earth is about the size of a marble. That means, you have to compress the earth to size of marble in order to turn it into a black hole. Now you can calculate the size of black holes.

### 3. The shape of the Black Hole

Image source: wikimedia

In some textbooks or sites, you might have seen black holes that look like funnels. This is because they are being illustrated from the perspective of gravitational force or other criteria. In reality, they look more like black sphere.

### 4. Black Holes Spin around an Axis

Image credit: hubblesite.org

Black holes (not all) spin around their axis and their situation is quite complicated. The surrounding space is dragged around creating a cosmic whirlpool. Instead of a single point, the singularity is an infinitely thin ring. The event horizon is composed of 2 imaginary spheres. Their region (known as ergosphere) is bounded by a static limit where you would rotate at the same speed (as well as direction) as the black hole although you can still escape.
“GRS 1915+105” is the heaviest stellar black hole in the Milky Way (10-18 times the mass of the Sun), which rotates 1,150 times per second.

### 5. Gravitational Pull of a Black Hole Depends on Mass and Distance

Image source: nasa.gov

Like a creature behind a cage, it’s ok to observe a black hole away from its event horizon. The gravitational pull of any black hole depends on its mass and distance from us.
That means, even if a nearby star like Sun suddenly compressed to become a black hole, it would not affect the Earth gravitationally. The earth would remain in its current orbit and we wouldn’t get sucked into the black hole.

### 6. They are Ultimate Data Storage Device

Image credit: scitechdaily.com

The event horizon is made of superhot bits of once organized information, broken down to its simplest form for maximum space-time efficiency. It’s like an infinite hard drive (or equivalent to Bekenstein Bound) that can store the complete history of millions of stars.

It may possible to use a black hole as a computing device. According to Professor Seth Lloyd, a black hole can compute 5 x 1050 operations per second, performing 1032 operations on 1016 bits.

### 7. Nearest and Massive Black hole

Our galaxy is covered with numerous black holes but the one most likely to destroy our planet is still beyond our solar system’s borders (there is no fix border as solar system is expanding at continuous rate). To be exact, the nearest black hole to the earth is 1600 light years away.

The biggest black hole (as per the theories) is 30,000 light years away from us which is around 30 million times as massive as our Sun.

### 8. They Eventually Evaporates

Image source: slate

The age of black hole is finite. They release radiations (known as Hawking radiation) due to quantum effects near the event horizon. As they emit radiation they are losing mass and this process has the potential to eventually kill the black hole.

### 9. Different Types of Black Holes

There are 3 types of black holes in the space (categorized according to their mass): Stellar, Supermassive, and Miniature black holes.
Stellar form when an extremely giant star collapses.
Supermassive black holes exist in the center of most galaxies (including Milky Way) and can have mass equivalent to millions of Suns.
Miniature are small ones (not discovered yet) which would have mass smaller than our Sun.

### 10. A Source for Travelling in Time

Photo credit: livescience.com

Black holes can be used to travel into the future (not past). According to the theory of relativity, an external observer would see a clock in gravitational field tick more slowly. Simply put, time runs much slower near a black hole.
Detailed version: How time travel will work?
They are not Always Black

People can’t see black hole because no light can get out from it. However, we do know that they emit electromagnetic radiations. The intensity of the radiation from blue (low) to white (high) indicates the ‘false color’.

### 11. The Laws of Physics Break Down Inside the Event Horizon

Image source: nasa.gov

Matters within black hole are crushed to infinite, and space & time cease to exist. The laws of physics break down inside event horizon; it is not really humanly possible to conceive of anything with infinite density and zero volume.

### 12. Minimum Mass of a Black Hole

No black hole is infinitely small. The minimum mass is above or equal to Planck mass which is about 22 microgram.

### 13. Space Distortion

Image credit: phys.org

Black holes have the capacity to distort space. They can shift the flow of time and alter the shape of space. Because black hole is continuously spinning, a strange effect occurs called frame-dragging. In this effect, space and time close to the black hole are actually dragged around with it. The space drags so intensely that it is not possible to move in opposite direction. It’s an infinite regression of distortions where there is no way to move forward.

### 14. Any Object can become a Black Hole

Stars aren’t the only things that eventually turn into black holes. If your cell phones were shrunk down to an infinitely small point and still retained its 100% mass, their density would reach astronomical levels which would make their gravitational force incredibly strong.

### 15. Black Holes can kill you in a horrible way

If you entered the event horizon, your body would be shredded apart into the smallest possible pieces. To escape its pull, you need to travel faster than light which is impossible. The pulling force towards the center known as tidal force acting on your head (if you are falling head-first) would be much stronger than the gravity acting on your toes. That would make your head accelerate way faster than your toes. This would stretch your body until it snapped apart. The same process would continue with other parts of your body.

### 16. You can Enter Black Hole in One Piece (Without Dying)

Relativity theory says that it is possible to travel through a black whole without crushing. There is a tunnel in space-time (called wormhole) that allows you to do so. However, your last moments would be little like being on the inside of distorted one way mirror. No one outside would be able to see you but you would’ve a distorted or blur view of them.
A special new theory suggests that the black holes could metamorphose into white hole through quantum process.

### 17. The Wormhole is Not at the Center of Black Hole

This is a common misconception i.e. there is a tunnel (or wormhole) in the middle of every black hole. All that exists at the center of black hole is extremely large amount of matter crushed into infinitely small amount of space.

### 18. They Produce Sound

Image source: nasa.gov

When black hole pulls something in, its event horizon supercharges the particle close to the speed of light, which produces sound.
You might be thinking sound can’t travel in vacuum, then how it is even possible. Actually, outer space is not a complete vacuum. It consists of a few hydrogen atoms (plus the other gases) per cubic meter, which serve as a medium for very low frequency sound waves.

### 19. They are Giant Source of Energy and Essential to Formation of Life

Image source: nasa.gov

In black hole the objects get squished together so hard that the space between the individual components of the atom is compressed, and it is broken down into subatomic particles. These particles are capable to create elements (including iron and carbon) which are essential to formation of life.
Also, splitting up the particles creates tremendous amount of energy. This conversion of mass into energy is about 50 times more efficient than nuclear reaction.

### 20. They Determine the Number of Stars in the Sky

Image source: npr.org

There are 1022 stars in the universe and this number is determined by the black holes. The particles emitted by the black holes expand into bubbles that ripple through a galaxy’s “star forming regions”. These particles heat up the gas cloud (star forming regions) and prevent the star from forming.
There is a balanced relationship between the activity of black holes and number of stars. Too many stars would make galaxy too hot and explosive for life to evolve, whereas not enough starts can prevent life from forming.

### 21. Black Hole Concept was discovered in 1783

Guess who discovered the concept of Black hole. No, not Albert Einstein. It was first conceived by an amateur astronomer, John Michell back in 1783. In 1915, Albert Einstein published the general theory of relativity and in 1916 Karl Schwarzchild used this theory to define the black hole.

## White Hole

### 22. The Concept of White Hole was introduced in 1964

The possibility of existence of white hole was first introduced by Igor Dmitriyevich Novikov in 1964. They (White Holes) are predicted as a part of solution of maximally extended version of the Schwarzschild vacuum describing the eternal black hole with no rotation and no charge.

### 23. White Holes Violate the 2nd Law of Thermodynamics

Second law of thermodynamics states that the amount of entropy in the universe can only stay the same or increase. Black holes are great at increasing entropy. Whereas, a white hole does the exact opposite work: it decreases the entropy by running the thing backwards, which is not allowed (at least in our universe).

### 24. White Holes exist for Very Short Duration

In general relativity, it doesn’t care whether you play time forward or backward. If the time can go in one direction (forward), it can just as easily go in other (backward).
So if black holes exist, so does white holes, which are holes played backward. So even if a white hole did somehow occur, it would be incredibly unstable because the universe does not like it when you violate the laws of physics.
That means, a real white hole would probably only last for a few seconds before it collapsed itself to become a black hole.

### 25. The Known White Hole

Image source: astro.caltech.edu

Back in 2006, there was a gamma ray burst (called 060614) that lasted for 102 seconds. Usually they have short duration, so it was quite surprising to see on lasting for almost two minutes.
Five years after that incident, some scientists suggested that the gamma burst was a white hole. The length and force of the outburst resonates with the idea of a white hole coming into existence, then imploding itself. Not all astronomers accepted this theory, though it is a likely possibility.

### 26. White Hole and Black Hole Together can create a Wormhole

Some scientists believe that you can make a wormhole by connecting a white hole and a black hole. Moreover, if you connected a white hole from the past and connected it to a black hole today, you could theoretically build a time machine. The possibilities are endless.

P.S: Astronomers still don’t know much about the white holes and it is possible that they will one day. It would require new advances in physics and astronomy.