Help with showing the existance of the Schwarzschild singularity at r=0.

Click For Summary

Discussion Overview

The discussion revolves around the existence of the Schwarzschild singularity at r=0, focusing on the mathematical derivation of expressions from the Schwarzschild metric that illustrate this singularity. Participants explore the implications of the metric's behavior as r approaches zero and the potential interpretation of singularities as part of an Einstein-Rosen bridge.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant references the Schwarzschild metric and seeks assistance in deriving a function of r that can be graphed to illustrate the singularity at r=0, questioning the existence of both positive and negative singularities.
  • Another participant notes that the term \(\frac{2GM}{c^2r}\) diverges as r approaches 0, implying that the metric diverges at this point.
  • A later reply clarifies the desire to graph a 2D spacetime representation that curves towards infinity as r approaches 0, while also mentioning the historical interpretation of singularities as ends of a wormhole, prompting a question about the mathematical derivation of these singularities.
  • One participant suggests using Kruskal or Penrose diagrams for analyzing spacetime and mentions rewriting the metric in Cartesian coordinates for an equatorial slice, while expressing skepticism about the physicality of singularities.

Areas of Agreement / Disagreement

Participants express differing views on the physical interpretation of singularities, with some questioning their physicality while others explore their mathematical implications. The discussion remains unresolved regarding the nature and derivation of singularities at r=0.

Contextual Notes

Limitations include the dependence on definitions of singularities and the unresolved mathematical steps in deriving expressions from the Schwarzschild metric.

blp
Messages
4
Reaction score
0
According to Wikipedia, if the metric was vacuum, spherically symmetric and static the Schwarzschild metric may be written in the form:
ds^2=((1-2GM/(c^2r))^-1)*dr^2+r^2*(dtheta^2+sin(theta)^2*dphi^2)-c^2*(1-2GM/(c^2r))*dt^2
I need someone to help me to derive an expression from the Schwarzschild metric that is a function of r that can be graphed, that clearly shows the singularity at r=0. Actually, their is apparently a pair of pos and neg singularities there. Is that true? Is that because there is a square root taken during it's derivation? Thanks.
 
Physics news on Phys.org
Surely

[tex]1- \frac{2GM}{c^2r}[/tex] clearly diverges when r = 0. And its inverse diverges when

[tex]1 = \frac{2GM}{c^2r}[/tex].
 
Sorry, I should have been clearer. Obviously ds^2 diverges at r=0, but I want some way of graphing a 2D spacetime clearly curving towards infinity in the z axis direction as r approaches 0.

Also concerning the pair of pos and neg singularities at r=0. I remember reading somewhere that shortly after Schwarzschild came up with the black hole solution to GR that Einstein and Rosen noticed the above pair of singularities and interpreted them as being the two ends of a wormhole and called it a Einstein-Rosen bridge. If that is true, I'm curious how the singularities were mathematically derived. Does anyone know?
 
I think space-times are analysed with Kruskal or Penrose diagrams. If you want to take an equatorial slice, then rewrite the metric in cartesian coordinates. I can't say any more than that, not having studied the singularites because I don't think they can be physical. But that's just an opinion.
 
Thanks! I'm going to re post this with a different title to see if someone else might know about this.
 

Similar threads

  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 50 ·
2
Replies
50
Views
4K
  • · Replies 9 ·
Replies
9
Views
4K
  • · Replies 18 ·
Replies
18
Views
5K
  • · Replies 3 ·
Replies
3
Views
1K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 42 ·
2
Replies
42
Views
5K
  • · Replies 7 ·
Replies
7
Views
3K
  • · Replies 18 ·
Replies
18
Views
2K
  • · Replies 7 ·
Replies
7
Views
2K