Calculating the event horizon of black holes.

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Discussion Overview

The discussion revolves around the calculation of the event horizon of black holes, specifically focusing on the Schwarzschild radius for non-rotating black holes. Participants explore the equations involved and the conceptual understanding of the event horizon.

Discussion Character

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

Main Points Raised

  • Some participants suggest that calculating the event horizon is possible and reference the Schwarzschild equation as a means to do so.
  • One participant proposes a method for calculating the event horizon by comparing it to the escape velocity of a satellite around Earth, equating it to the speed of light.
  • There is a clarification that the term "radius of the black hole" is often used interchangeably with "radius of the horizon," though some participants emphasize the distinction.
  • Participants express a desire for further explanation on how to use the Schwarzschild equation effectively.

Areas of Agreement / Disagreement

Participants generally agree that the Schwarzschild equation can be used to calculate the event horizon, but there is some contention regarding terminology and the clarity of the explanation of the equation's application.

Contextual Notes

Some assumptions about the nature of black holes and the conditions under which the Schwarzschild equation applies are not fully explored. The discussion does not resolve the nuances of terminology related to the radius of black holes versus the event horizon.

William Henley
Hello, I remember hearing somewhere that it is possible to calculate the event horizon, I was just wondering if this is possible and what equations are used to calculate it.
 
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"hearing somewhere" is not a very solid reference, although it happens to be correct in this case. It is rather trivial for a non-rotating black hole. Have you done any research at all?
 
William Henley said:
Hello, I remember hearing somewhere that it is possible to calculate the event horizon, I was just wondering if this is possible and what equations are used to calculate it.

I would give you a suggestion, as it very simple to do and quite satisfying... Think of a satellite around the Earth and find its escape velocity, you should get something very simple, function of the mass of the Earth and the distance to the satellite. Then equalize that velocity with the velocity of light, solve for the distance and voila, you get the radius of the horizon (or the Schwarzschild radius, as it is called)
Virgil.
 
phinds said:
"hearing somewhere" is not a very solid reference, although it happens to be correct in this case. It is rather trivial for a non-rotating black hole. Have you done any research at all?
Yeah I have, and I found that the Schwarzschild equation can be used to calculate the radius of the black hole. But I was wondering if someone could explain how to use the equation.
 
William Henley said:
Yeah I have, and I found that the Schwarzschild equation can be used to calculate the radius of the black hole. But I was wondering if someone could explain how to use the equation.

Just an observation, it is not the radius of the black hole, but the radius of the horizon of the black hole.
 
virgil1612 said:
Just an observation, it is not the radius of the black hole, but the radius of the horizon of the black hole.
Which is usually called "the radius of the black hole" since a black hole does not have any other radius.
 

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