Exercise 3


Falling into a black hole: The singularity and spagettification

Transcript:

Obviously, we can’t send humans anywhere in a black hole but a robot? Well sure! A robotic probe could transmit data back just before it goes over the edge.
That edge of a black hole is called the event horizon, it’s the edge of time and space at least in the universe we know.
“We call the event horizon, event horizon, quite simply because it separates space into two regions. It’s not a physical surface, you might not even notice it, if you’re falling through it, but ultimately once you’re inside of it, you’re doomed.”
As you approach the event horizon, gravity gets stronger and very strange things start to happen.
“As you fall into a black hole feet first, your feet are closer to the black hole and so the gravity they feel is stronger. Your head is not quite as close and so the gravity it feels is less, and basically what happens is you get stretched out, your feet are being pulled much harder than your head, and you’re like a piece of taffy being pulled between two strong people”
“As you get thinner, and thinner and thinner, as you get closer, and closer and closer, you’re undergoing a process we call spagettification, because you basically turn into a long thin tube of pasta”
Gravity will stretch a robotic probe to the limit, then rip it apart. But imagine if the probe was strong enough to survive and keep going. As it gets close to the event horizon, everything goes crazy. Gravity is so extreme, it stops Time!
“We think of time as being endless, however in a black hole in some sense time stops.”
“This sounds like it’s nuts but, that’s the way it works, it’s in the maths, it’s actually woven into the fabric of the universe itself.”

If you were to watch from a distance, the robot probe would seem to slow down as it gets closer to the black hole. Then it would appear to stop completely.

The whole process might just take a brief moment but from the outside, you appear to freeze and fall ever more slowly. You actually can never observe an object fall all the way through the event horizon, it literally freezes at the surface, because its clock is going infinitely slowly compared to yours.

In reality, the probe hasn’t stopped at all. It keeps going, and crosses the event horizon. If the probe points its cameras backwards towards the entrance of the black hole, it’ll see light being sucked in. If it points the camera forward at first it sees only black, but as it moves toward the heart of the black hole it encounters the most bizarre place in the Universe. The black hole’s immense gravity pulls everything down to an unimaginably small point at its center. Scientists call it the Singularity.

We really just don’t know what happens at the center of a black hole, the densities are so great that the laws of physics break down as we know them.

A singularity is the point of infinite gravity where space and time become meaningless. Now that is ridiculous. A singularity is basically a word for saying “I don’t know”, It’s a word for saying “I’m clueless”.

Even now, Scientists can’t really answer the question “What is a black hole ?”.

It’s upsetting a little bit to think that there are objects out there that are breaking the laws of physics. There must be bigger laws that are being used by these black holes, that are being obeyed by these black holes, that we just don’t understand yet.

Summarize the listening with its main points and write about what you think about black holes.

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