Global casual structure of space-time, well-behaved function

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Discussion Overview

The discussion revolves around a proposed black hole solution characterized by specific metric and scalar functions. Participants are examining the global causal structure of the space-time solution and questioning the well-behaved nature of the dilaton field as \( r \) approaches infinity. The scope includes theoretical aspects of general relativity and black hole physics.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant presents a black hole solution with metric function \( f(r) \) and scalar function \( \varphi(r) \), asking about the global causal structure and the behavior of the dilaton field at infinity.
  • Another participant questions the validity of the solution as a black hole, seeking clarification on the reasoning behind this classification.
  • Several participants express that the initial post lacks sufficient information and context, suggesting that the questions should be divided into separate threads for clarity.
  • One participant indicates that knowing \( f(r) \) and \( \varphi(r) \) does not provide enough information to derive the line element or metric, which is necessary to discuss the global causal structure.

Areas of Agreement / Disagreement

Participants generally agree that the initial post lacks clarity and sufficient detail. There is disagreement regarding the classification of the solution as a black hole, and the discussion remains unresolved regarding the implications of the proposed metric and scalar functions.

Contextual Notes

Limitations include the absence of a complete metric description and insufficient context for the proposed functions, which may hinder understanding of the global causal structure.

dhalilsim
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I obtained the black hole solution whose the metric function f(r) and scalar function ##\varphi(r)## are ;

##f(r)=\frac{1}{4}+\left(\frac{Z^{2}}{2r^{2}}\right)^{2}-\frac{1}{3}\Lambda r^{2}##
##\varphi(r)=\pm\left(\frac{1}{\sqrt{2}l}\right)r##
where ##Z##, ##\Lambda## and ##l## are just constants.

What is the global causal structure of this space-time solution described by Eqs. above?
Is the dilaton field well-behaved for r —-> infinity?

[Moderator's Note: deleted the second part of the post, needs to be posted in a separate thread.]
 
Last edited by a moderator:
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These look like two unrelated questions, which you should ask in two separate threads. Also, there is far too little information for anyone to be able to understand what you're actually asking about.
 
dhalilsim said:
I obtained the black hole solution

Why do you think this solution describes a black hole?
 
bcrowell said:
These look like two unrelated questions, which you should ask in two separate threads.

Agreed, so I deleted the second one from the OP of this thread. dhalilsim, please start a separate thread if you want an answer to the other question (and it would help if you actually gave the specific equations you are asking about).
 
dhalilsim said:
whose the metric function f(r) and scalar function ##\varphi(r)##

What are these supposed to mean? As bcrowell says, there is far too little information here to understand what you are talking about. Please give a reference or quite a bit more context (preferably both).
 
Last edited:
Telling us f(r) and ##\varphi(r)## does not directly gives us the line element / metric. I'm not sure what I'll be able to say about the global causal structure given the metric, but the first step is to get the metric.
 

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