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What are they? -

Black holes are regions in space where gravity is so intense that nothing, not even light, can escape from them. They are sometimes hundreds of times bigger than our Sun, and are invisible!

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How it’s made -

Black holes form when massive stars exhaust their nuclear fuel and collapse under the weight of their own gravity. This collapse causes the core to compress into an infinitely dense point called a singularity, surrounded by an event horizon.

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Event horizon -

The event horizon is the boundary around a black hole beyond which nothing can return. Once an object crosses this threshold, it is inevitably drawn towards the singularity and cannot escape the black hole's gravitational pull.

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Singularity -

At the center of a black hole lies the singularity, a point of infinite density where the laws of physics as we know them break down. The singularity is where the star's mass has been compressed into an infinitely small space.

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Types -

There are several types of black holes, including stellar black holes formed from collapsing stars and even supermassive black holes found at galaxy centers.

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Supermassive black holes -

Supermassive black holes are millions to billions of times the mass of the Sun, and reside at the centers of galaxies, including our Milky Way. Many scientists are still debating and researching their formation, but they are crucial components in the evolution of galaxies.

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Stellar black holes -

Stellar black holes are formed from the remnants of massive stars. When such a star exhausts its nuclear fuel, it undergoes a supernova explosion, and the core may collapse into a black hole if it is massive enough.

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Intermediate black holes -

Intermediate black holes are believed to form through the merging of smaller black holes or through the collapse of massive star clusters. They serve as a bridge in size between stellar and supermassive black holes.

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Quasars -

Quasars are extremely bright and distant objects powered by supermassive black holes at the centers of young galaxies. The intense radiation comes from the buildup of matter, which releases vast amounts of energy as it falls into the black hole.

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Hawking radiation -

According to theoretical physicist Stephen Hawking, black holes can emit radiation that releases small particles of energy from the black hole. This process, known as Hawking radiation, can eventually cause black holes to evaporate over extremely long timescales.

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Accretion disks -

As matter falls into a black hole, it forms an accretion disk, which heats up and emits X-rays and other radiation as it spirals inward. This matter can be made of dust particles or even light itself.

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Fabric of space -

Imagine that the infinity of space is nothing more than a piece of fabric, and each celestial body (stars, planets, black holes) is a marble sitting on top. Compared with other celestial objects, black holes are a lot heavier, and their presence distorts the very fabric of space.

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Information paradox -

The black hole information paradox questions whether information that falls into a black hole is lost forever or somehow preserved. This challenges our understanding of physics, since we have yet to grasp the full extent of what lies inside these celestial bodies.

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Black hole shadow -

In 2019, the Event Horizon Telescope (EHT) captured the first-ever image of a black hole's shadow, providing direct visual evidence of a black hole's existence. The image was of the black hole at the center of galaxy Messier 87, and has been heralded as a monumental breakthrough in astrophysics.

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Jet emissions -

Some black holes produce powerful jets of particles and radiation that shoot out from their poles. These jets can extend for thousands of light-years and are thought to be powered by the black hole's rotation and magnetic fields.

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Simulation -

Earlier this year, NASA created a simulation of what it would look like to fall into a supermassive black hole that is 4.3 million times the mass of our Sun. That is equivalent to the black hole currently at the center of the Milky Way galaxy.

Image credit: NASA's Goddard Space Flight Center/J. Schnittman and B. Powell

© NASA's Goddard Space Flight Center/J. Schnittman and B. Powell

Powerful computing -

A typical laptop would have taken decades to create the simulation, yet the Discover supercomputer at NASA’s Goddard Space Flight Center was able to perform the feat in five days, using only 0.3% of its processing power. But the question still remains: what would you experience if you fell into a black hole?

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Approaching a black hole -

As you approach a black hole, you would feel a major increase in gravity. The black hole's immense gravitational forces would begin to distort your perception of time and space, making the environment around you increasingly bizarre and surreal.

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Increasing temperature -

The accretion disk of the black hole, composed of matter spiraling in, would be incredibly hot. As you get closer, you would likely be exposed to intense radiation, heating you up to fatal temperatures as you are pulled closer.

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Spaghettification -

Once close enough, the differential gravitational forces (known as tidal forces) would become extreme. The gravitational pull on your feet would be much stronger than on your head, stretching the body into a long, thin shape in a process called spaghettification.

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Time from outside -

Due to the intense gravitational field, time dilation becomes significant. To an outside observer, it would appear as though you are slowing down as you fall into the black hole, until you ultimately seem to freeze at the edge of the event horizon without crossing it.

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Time from inside -

As you fall, time would seem to continue normally, but you would observe the universe outside speeding up dramatically. The entire future history of the universe could play out in what seems like a short time.

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Point of no return -

From your perspective, you would pass the event horizon without noticing any immediate changes. However, once crossed, there is no turning back, and you are inevitably drawn towards the singularity. At this point, you would see nothing more than the fading light from the accretion disk around the black hole.

Image credit: NASA's Goddard Space Flight Center/J. Schnittman and B. Powell

© NASA's Goddard Space Flight Center/J. Schnittman and B. Powell

Outside communication -

Communication with the outside world would cease as signals could no longer escape the black hole's gravitational grip. Any attempts to send messages back would fail, leaving you isolated from the rest of the universe.

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Radiation exposure -

The infall would expose you to increasing levels of radiation from the accretion disk and other matter being pulled into the black hole. This radiation could be lethal long before you physically reach the singularity.

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Approaching the singularity -

After crossing the event horizon, you would continue to fall towards the singularity at the center of the black hole. The gravitational forces would increase further, compressing and stretching your body even more intensely.

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Theoretical end point -

Near the singularity, the laws of physics as we know them cease to function. No one knows what exact conditions lie at the center of a black hole, but general relativity predicts that there would be infinite density and zero volume.

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Theoretical quantum effects -

Some theories suggest that quantum effects near the singularity could create a "firewall" of intense energy that would vaporize anything that reaches this point. However, this is still a topic of intense debate and remains speculative.

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Scientific exploration -

Studying black holes helps scientists explore the boundaries of physics and the nature of the universe. There is still much to learn about their existence, but new technologies will help develop our understanding of these mysterious forces.

Sources: (NASA) (Business Insider) (Space.com) (Encyclopedia Britannica) (National Geographic)

See also: Are there other planets like ours?

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