What would happen if you fell into a black hole?

What would happen if you fell into a black hole?

Black holes are among the most enigmatic and extreme astronomical phenomena we know of in the universe. But what if you fell into it?

These cosmic bodies are regions of spacetime where gravity is so extreme that nothing, not even light, can escape.

Most of the time, black holes form as the remnants of dead stars in cataclysmic cosmic explosions called supernovae.

What is the structure of a black hole?

An astronaut falls into a black hole
Stock image: Artist’s rendering of an astronaut falling into a black hole. What would happen if you fell into a black hole?

At the center of a black hole is the singularity – a one-dimensional point where gravity is believed to be infinite and where the laws of physics as we know them break down.

Around this is a region known as the event horizon, the boundary beyond which nothing can escape due to extreme gravitational pull. The event horizon is so named because it is impossible to observe an event taking place there.

Black holes fall into two main size classes: stellar and supermassive (although recent research has revealed that there may also be an intermediate class). Stellar black holes tend to have a mass several times that of our sun. Supermassive black holes can have masses ranging from millions to billions of solar masses.

What would happen if you got too close to a black hole?

So, let’s imagine a hypothetical situation in which humanity has mastered interstellar travel (the nearest black holes are believed to be thousands of light-years away) and an astronaut has strayed too close to a black hole , either in a spacecraft or on a spacewalk. What would happen, and how close is it?

“The ‘point of no return’ for black holes is the event horizon,” said Ben Farr, a gravitational wave physicist and astronomer at the University of Oregon. Newsweek. “This is the point at which the curvature of space caused by the black hole is so extreme that even light, the fastest particles in the universe, can go nowhere except to the center of the black hole once ‘she passed him.”

According to Farr, the event horizon of a typical “stellar mass” black hole, say 10 times the mass of our sun, is about 30 kilometers (19 miles) from its center. For a supermassive black hole the size of the one at the center of our galaxy, that figure is much larger, around 12 million kilometers (7.4 million miles).

If you got too close to a black hole, you’d be sent plummeting towards the center, with gravitational forces increasing the closer you got, creating a pulling force on your body.

But the experience of an astronaut approaching the event horizon of a black hole depends very much on its size. Perhaps counterintuitively, supermassive black holes may be safer to approach than stellar-mass holes, at least in the short term.

“A stellar-mass black hole has such extreme tidal forces outside its event horizon (an astronaut falling feet first would feel stronger gravity at his feet than at his head) that our astronaut would be torn apart long before to reach the event horizon,” Farr said. “Tidal forces are felt by an object when the force of gravity it experiences from a massive object is stronger on one of its sides than on the other.”

Due to the extreme tidal forces, the astronaut will experience an effect aptly named “spaghettification” – essentially they would be stretched vertically, like spaghetti dough being stretched by a chef (but much more violent).

“Because the event horizon is so much closer to a small black hole than to a large black hole, the effect will be much larger for a small black hole,” said physicist and astronomer Glenn Starkman at the Case Western Reserve University. Newsweek.

In fact, the tidal forces around a stellar-mass black hole would be strong enough to spaghettile the astronaut and his spacecraft probably a few hundred miles away.

Astronaut falling into a black hole
Stock image: Artist’s rendering of an astronaut falling into a black hole. Anyone falling into a black hole would end up being torn apart by the extreme gravitational forces.

Approaching a supermassive black hole would be surprisingly peaceful at first, Farr says, and a plummeting astronaut might even be able to reach and cross its event horizon, probably without noticing anything in particular.

“The astronaut traversing the supermassive black hole should enjoy the trip,” Starkman said. “They probably won’t notice anything unusual, except that communications from their home will become strange – it will seem like they aren’t keeping up to date with your travels.”

“That’s because your messages take longer and longer to get out of the black hole’s gravity. This is true for both stellar and supermassive black holes,” he said. “Your friends back home will see you getting closer and closer to the event horizon, but will never see you crossing. However, you will actually cross in no time.”

In the case of the supermassive black hole, the astronaut would be able to find a stable orbit for their spacecraft as close as 24 million kilometers (15 million miles) above its event horizon, which would require no fuel to maintain, according to Farr.

“This is where the gravity around the black hole becomes noticeably different: the closer it gets, the more the astronaut will have to use their spacecraft’s engines to avoid falling into the black hole, and the closer it gets to the black hole. ‘event horizon, the more thrust she’ll need from her spaceship’s engines to escape the black hole, and it becomes infinite as she crosses the event horizon,” Farr said.

What happens after you pass the event horizon?

If the astronaut somehow made it to the event horizon of a supermassive black hole, things could get really weird.

“What I said above assumes that general relativity is the correct theory at the event horizon. Not everyone agrees that it is,” Starkman said. “Some people think that conventional physics breaks down at the event horizon, and all sorts of weird things happen to you, including that you may never be able to break through the event horizon.”

But if you passed the event horizon, what could the astronaut see?

“Once inside the event horizon, there would be substantial distortion of gravitational lensing images (the effect of light traveling on curved paths due to the strong curvature of spacetime ), our astronaut could still see events happening outside the black hole,” Farr said. .

However, once past the event horizon, the astronaut’s fate is likely sealed. They would be spaghettified before reaching the singularity, probably a few minutes after it passed through in the case of a supermassive black hole.

“If our astronaut shines a light toward the event horizon, even those photons will end up at the singularity,” Farr said.

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