Embedding Diagram of Weyl Metric in ##R^3##

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Discussion Overview

The discussion revolves around the possibility of embedding a constant slice of a Weyl metric in three-dimensional Euclidean space, specifically focusing on a metric dependent on both ##\rho## and ##z##. Participants explore the challenges associated with embedding a specific line element derived from a two black holed Majumdar-Papapetrou metric.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant questions the feasibility of embedding the ##\phi##=constant slice of a Weyl metric in ##R^3##, noting the dependence on ##\rho## and ##z##.
  • Another participant suggests that the original question may be too general and requires further specification to be answerable.
  • A participant proposes embedding the line element ##ds^2=U^2(dx^2+dy^2)##, where ##U=1+\frac{1}{\sqrt{(x-1)^2+y^2}}+\frac{1}{\sqrt{(x+1)^2+y^2}}##, into 3D Euclidean space, highlighting the challenge of the indefinite integral.
  • Concerns are raised regarding the undefined nature of the function ##U## at specific points, which are identified as degenerate horizons of black holes.
  • A later reply indicates that the embedding function may involve an indefinite integral likely expressed in terms of elliptic integrals, suggesting a potential shift in the discussion's focus to pure mathematics.

Areas of Agreement / Disagreement

The discussion reflects a lack of consensus, with multiple competing views on the feasibility and approach to embedding the Weyl metric and the specific line element. Participants express uncertainty regarding the integration process and the implications of undefined points in the metric.

Contextual Notes

Participants note limitations related to the generality of the original question, the undefined nature of the function ##U## at certain points, and the potential complexity of the resulting integrals, which may not have straightforward solutions.

Onyx
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TL;DR
Is it possible to make an embedding of the ##\phi##=constant slice of a Weyl metric in ##R^3##?
Is it possible to make an embedding of the ##\phi##=constant slice of a Weyl metric in ##R^3##? In particular, I'm thinking of a metric where the components are both ##\rho## and ##z## dependent.
 
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Has anyone seen this question?
 
Onyx said:
a Weyl metric
This is a very general category, so I'm not sure your question is answerable unless you can narrow things down more.
 
PeterDonis said:
This is a very general category, so I'm not sure your question is answerable unless you can narrow things down more.
Actually, forget about the Weyl metric for now. I am specifically trying to embed ##ds^2=U^2(dx^2+dy^2)##, where ##U=1+\frac{1}{\sqrt{(x-1)^2+y^2}}+\frac{1}{\sqrt{(x+1)^2+y^2}}##, into 3D Euclidean space. The only trouble is, the resulting function clearly does not have an indefinite integral, so there is the question of where to start the integration from.
 
Onyx said:
I am specifically trying to embed ##ds^2=U^2(dx^2+dy^2)##, where ##U=1+\frac{1}{\sqrt{(x-1)^2+y^2}}+\frac{1}{\sqrt{(x+1)^2+y^2}}##, into 3D Euclidean space.
Where does this line element come from?

One obvious issue is that the function ##U## is undefined at the ##(x, y)## points ##(1, 0)## and ##(-1, 0)##.
 
PeterDonis said:
Where does this line element come from?

One obvious issue is that the function ##U## is undefined at the ##(x, y)## points ##(1, 0)## and ##(-1, 0)##.
Yes, those are supposed to be the degenerate horizons of the black holes I think. I got this metric from a 2 black holed Majumdar-Papapetrou metric with black holes centered at the points you mentioned. I took the ##\phi=constant## slice and replaced what is usually ##p## and ##z## with ##x## and ##y##.
 
Okay, I think I figured out through pullback the form of h(x,y), the embedding function, is. It involves an indefinite integral whose answer is probably expressed with elliptic integrals in a way that I don't know. Maybe that question would be more at home in the pure math section of the website at this point.
 

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