What does a black hole look like from the inside?

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Discussion Overview

The discussion centers around the conceptual understanding of what one might observe inside a black hole, exploring theoretical implications of light behavior and the nature of singularities. Participants engage with ideas related to gravity, escape velocity, and the structure of spacetime within black holes.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant suggests that if a black hole is large enough, it might be possible to travel within the event horizon without immediate danger, prompting questions about visibility and light behavior inside.
  • There is a proposition that light, similar to a rocket that cannot reach escape velocity, might behave as if reflecting off a mirror-like surface within the black hole.
  • Another participant counters that light would not return to a higher radial coordinate and emphasizes that inside a black hole, the radial coordinate represents time rather than distance.
  • Questions are raised about whether light could enter an orbit around the singularity, with responses indicating that such orbits occur outside the event horizon.
  • One participant notes that the singularity cannot be described by current theories, suggesting a fundamental limit to understanding conditions there.
  • Another participant expresses appreciation for the clarification regarding the nature of matter and the singularity, indicating a learning moment.

Areas of Agreement / Disagreement

Participants express differing views on the behavior of light within a black hole, particularly regarding the possibility of reflective surfaces and orbits. The discussion remains unresolved with multiple competing ideas presented.

Contextual Notes

Participants acknowledge limitations in understanding the singularity and the implications of spacetime behavior within black holes, indicating a reliance on theoretical models that may not fully capture the phenomena.

GiantSheeps
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According to this video, , if a black hole is large enough you could actually travel for some time within the event horizon without dying because the event horizon is so far from the actual singularity. So, assuming that's true, what would you see while you were inside the black hole?

Here's what i think: if you launch a rocket on Earth that can't reach escape velocity, at certain point it'll just come straight back down. Would it be the same for light? Light cannot reach escape velocity so would it just come straight back down at a certain point? If that's the case, wouldn't that make a sort of mirror like surface? The light goes up and comes back down as if reflecting off a mirror?

And then on top of that, just because light can't escape it doesn't mean light can't enter. So would it be a reflective surface as well as a one way see through window to the rest of the universe?

And one last thing, is it at all possible that light that enters the black hole could somehow enter an orbit around the singularity?

I know I probably got a lot of this wrong, so I thank you for your patience and any help would be greatly appreciated!
 
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GiantSheeps said:
So, assuming that's true, what would you see while you were inside the black hole?
The first thing you need to realize is that the black hole is very different from your classical gravity picture. In a black hole, space and time have very different meanings from those you would find in the weak gravitational field of a planet or even a regular star. The singularity is not a position in space, rather it is in the future of all observers.

GiantSheeps said:
Here's what i think: if you launch a rocket on Earth that can't reach escape velocity, at certain point it'll just come straight back down. Would it be the same for light? Light cannot reach escape velocity so would it just come straight back down at a certain point? If that's the case, wouldn't that make a sort of mirror like surface? The light goes up and comes back down as if reflecting off a mirror?
It is really not a question of escape velocity, again the classical view of weak gravitational fields comes back to haunt you. The light would never reach values of the radial coordinate which are larger than where it started. All events in the future light cone for any given event inside the black hole has a smaller radial coordinate. Note that the radial coordinate inside the black hole does not represent a distance, but rather a time. There really is no concept of "towards the centre" inside the black hole.

GiantSheeps said:
And then on top of that, just because light can't escape it doesn't mean light can't enter. So would it be a reflective surface as well as a one way see through window to the rest of the universe?
No.

GiantSheeps said:
And one last thing, is it at all possible that light that enters the black hole could somehow enter an orbit around the singularity?

No. The circular orbits of light around a black hole occur at values of r which are 1.5 times the Schwarzschild radius.
 
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GiantSheeps said:
... is it at all possible that light that enters the black hole could somehow enter an orbit around the singularity?
It's possible in the sense that there might be a chocolate teapot orbiting Mars.
The singularity in a black hole is not a physical object.
The singularity word means that conditions at the center of a black hole cannot be described by our best theories.
(Or in other words, nobody knows what is going on there)
We do know though, that matter made of atoms, the familiar stuff of the world which we live in and can observe, that can't exist.
 
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rootone said:
We do know though, that matter made of atoms, the familiar stuff of the world which we live in and can observe, that can't exist.
Thanks for that perspective, I've never heard it put that way.
 
Orodruin said:
The first thing you need to realize is that the black hole is very different from your classical gravity picture. In a black hole, space and time have very different meanings from those you would find in the weak gravitational field of a planet or even a regular star. The singularity is not a position in space, rather it is in the future of all observers.It is really not a question of escape velocity, again the classical view of weak gravitational fields comes back to haunt you. The light would never reach values of the radial coordinate which are larger than where it started. All events in the future light cone for any given event inside the black hole has a smaller radial coordinate. Note that the radial coordinate inside the black hole does not represent a distance, but rather a time. There really is no concept of "towards the centre" inside the black hole.No.
No. The circular orbits of light around a black hole occur at values of r which are 1.5 times the Schwarzschild radius.

Okay! thank you so much for the info sir. It's greatly appreciated. Looks like I need to firm up my understanding of what a black hole even is :)

Thanks again!
 
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