Spherical symmetric collapse of pressureless dust

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Discussion Overview

The discussion revolves around the exact solutions for the spherical symmetric collapse of pressureless dust within the context of general relativity. Participants explore various models and references related to this phenomenon, including the Schwarzschild solution and the Oppenheimer-Snyder collapse.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant inquires about the existence of an exact solution for the spherical symmetric collapse of pressureless dust and whether a Schwarzschild solution can be observed for r > Rdust with a shrinking Rdust(t).
  • Another participant suggests that a form of the Friedmann solution can be embedded within an exterior Schwarzschild spacetime, noting uncertainty about whether the interior can be pressureless, later identifying it as the Tolman solution.
  • A different participant proposes that the Oppenheimer-Snyder collapse is relevant for a uniform ball of dust and references additional literature, including Israel's paper on the collapse of a thin spherical shell of dust and sections from Eric Poisson's text and Padmanabhan's work.

Areas of Agreement / Disagreement

Participants present multiple competing views and references regarding the solutions and models applicable to the collapse of pressureless dust, indicating that the discussion remains unresolved.

Contextual Notes

Some assumptions about the nature of the dust and the conditions for collapse are not fully articulated, and the applicability of various solutions may depend on specific definitions and contexts.

tom.stoer
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Is there an exact solution for the spherical symmetric collaps of pressureless dust? Can one see a Schwarzschild solution for r > Rdust with shrinking Rdust(t) ?
 
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It is possible to embed a form of the Friedmann solution inside an exterior Schwarzschild spacetime. I can't remember if the interior bit can be made pressureless. My only reference right now is Stephani's "General Relativity".

[edit] The interior can be dust. So I guess this fits. This is the Tolman solution, it turns out.
 
Last edited:
Assuming you are looking for the collapse of a uniform ball of dust, I believe what you want is the Oppenheimer-Snyder collapse: http://grwiki.physics.ncsu.edu/wiki/Oppenheimer-Snyder_Collapse

See also if you can get access to Israel's paper on the collapse of a thin spherical shell of dust: http://adsabs.harvard.edu/abs/1967PhRv..153.1388I

Eric Poisson talks about both of these things (Oppenheimer-Snyder collapse and thin shell collapse) in sections 3.8 and 3.9 of his text "A Relativist's Toolkit: The Mathematics of Black Hole Mechanics".

Also, see the following passages from section 7.6 of Padmanabhan "Gravitation: Foundations and Frontiers":
http://postimg.org/image/48aevjpkp/
http://postimg.org/image/8swlah9a1/
http://postimg.org/image/upj4aumgp/

The rest of the section is about the nature of the collapse obtained from such solutions.
 
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Great - thx!
 

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