How much space does a black hole take up?

Astronomy ^ | 27 Apr, 2020 | Caitlyn Buongiorno

[Don W]

Absolutely none until you reach the event horizon, at which point it BECOMES the entire universe...

[SunkenCiv]

This is a little hard to wrap your head around, but shadows can move faster than the speed of light, even though nothing can move faster than the speed of light. In a second, we'll explain how exactly that's possible without breaking the most fundamental law of physics. But first, this thought experiment might make things clearer.

Imagine you have a light that's powerful enough to reach the planet Jupiter. Imagine also that it casts that beam in a cone that's broad enough to cover the entire diameter of the planet. When you pass your finger over the lens, the shadow will cross the entire diameter of the planet -- a distance of 86,881 miles (139,821 kilometers). The speed of light is 186,000 miles per second (299,338 kilometers per second). So if it takes you less than half a second to move your hand that distance, then that shadow will have "broken" the speed of light.

So, remember how we said that nothing can move faster than the speed of light? Well, that's the key. Shadows aren't anything. Shadows are the absence of something -- specifically, photons, or particles of light. Since there's nothing that's actually traveling the distance, the only thing that's "moving" is an area where photons aren't. There's no information that's being transmitted faster than light, only a blockage of information. That means your interplanetary shadow-puppet show doesn't break any physical laws -- only the hearts of your interplanetary audience.

Darkness Is Faster Than the Speed of Light | Reuben Westmaas | August 01, 2019

What Is The Speed of Dark? | Vsauce | Published on July 29, 2014

[SunkenCiv]

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[Ozark Tom]

The circumference for a given mass varies dependent on rate of spin.

[Ozark Tom]

The event horizon is an arbitrary definition for the size of a black hole.

[SuperLuminal]

"The movie “Interstellar” is great. They spend a brief interval on a planet just outside the event horizon, and find 22 years have elapsed on the orbiting craft that launched their probe."

Marked for comment later...

[Nateman]

The bigger a black hole is the less dense it becomes. Another odd feature is Hawking radiation. Due to quantum effects black holes actually emit blue tinged radiation. The bigger they are the less this effect has on it’s over all mass. They do eventually get to the point where they pop in a mini explosion but that can easily be over a google amount of years before that happens.

[SuperLuminal]

"The movie “Interstellar” is great. They spend a brief interval on a planet just outside the event horizon, and find 22 years have elapsed on the orbiting craft that launched their probe."

One of my favorite TV sci fi series was Andromeda... The "brief" interval spent just outside the event horizon cost that ship & captain "300 years", when they, the ship & captain, were pulled away from the hole's clutches by a seedy group of salvage hunters and the story begins...

[Deaf Smith]

My guess is that darkness/shadow does not travel.

Dark/black is the absence of light as cold is the absence of heat.

The shadow of the finger over the lens is the blocking/interruption of the travel of light.

Dark/black took the place of removed light since dark/black is always there.

[Deaf Smith]

And I just now read your link.

[TexasTransplant]

bkmk

[SunkenCiv]

:^)