What Does the Dirac Delta Function Look Like in Curved Spacetime?

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Discussion Overview

The discussion centers on the Dirac delta function in the context of curved spacetime, particularly exploring how its representation might differ from that in flat spacetime. Participants are examining theoretical implications, potential applications in quantum mechanics, and references to relevant literature.

Discussion Character

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

Main Points Raised

  • One participant questions how the Dirac delta function appears in curved spacetime, suggesting that its representation may differ from flat spacetime.
  • Another participant asserts that the definition of the Dirac delta function as a distribution is independent of the curvature of space, implying a misunderstanding of the original question.
  • A participant expresses interest in the application of the Dirac delta function within the framework of path integrals in quantum mechanics, noting that existing treatments are primarily in flat spacetime.
  • References to Hagen Kleinert's work are made, with one participant suggesting his book on path integrals as a resource for understanding curvature and torsion.
  • Some participants express difficulty in following Kleinert's presentation, citing differences in pedagogical approach and a desire for clearer explanations of complex concepts.
  • Concerns are raised about the accessibility of Kleinert's work, particularly regarding the use of advanced terminology without sufficient explanation.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the nature of the Dirac delta function in curved spacetime. There are competing views regarding its definition and representation, as well as differing opinions on the clarity and accessibility of existing literature.

Contextual Notes

Some participants highlight limitations in understanding due to the complexity of the material and the use of specialized terminology that may not be widely recognized.

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Does anyone know what the Dirac delta function would look like in a space with curvature and torsion? The Dirac delta function is a type of distribution. But that distribution might look differently in curved spacetime than in flat spacetime. I wonder what it would look like in curved spacetime. Any help? Thanks.
 
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The Dirac delta function is a distribution as you say. The definition of any function or distribution has nothing to do with "curved" or flat space. Perhaps you mean something else.
 
HallsofIvy said:
The Dirac delta function is a distribution as you say. The definition of any function or distribution has nothing to do with "curved" or flat space. Perhaps you mean something else.

I suppose that being a distribution really doesn't matter. I was thinking that a distribution might help with visualizing physically on the situation.

Where I am going is that I have seen where the path integral of quantum mechanics is developed from the definition of the Dirac delta functin. This development is in flat spacetime. So I wonder if a similar development can be done in curved spacetime. Any help would be appreciated. Thanks.
 
Try the book on Path Integrals by Hagen Kleinert. He treats path integrals in spaces with curvature and torsion.
 
Pere Callahan said:
Try the book on Path Integrals by Hagen Kleinert. He treats path integrals in spaces with curvature and torsion.

Yes, Kleinert has an on-line presentation of this at:

http://www.physik.fu-berlin.de/~kleinert/kleiner_re252/node11.html

I can follow it until about equation 115 where he got and complex exponential for the Jacobian.
 
I cannot follow Kleinert's presentation at all. :smile: I have his book and I once took two courses on path integrals taught by him, but his way of doing things is just too different from mine.
Still the book is a great resource if you're prepared for pages and pages of weird and seemingly unmotivated/unjustified calculations (only my opinion)
 
Pere Callahan said:
I cannot follow Kleinert's presentation at all. :smile: I have his book and I once took two courses on path integrals taught by him, but his way of doing things is just too different from mine.
Still the book is a great resource if you're prepared for pages and pages of weird and seemingly unmotivated/unjustified calculations (only my opinion)


Does he use a lot of differential form notation, etc? Hagen Kleinert's name comes up a lot when researching path integrals in curved spacetime. But I wish there were more agreement that his treatment is acceptable. And it would be nice if there were an expanded version of his derivations for us dummies. As it is, he mentions things like "nonholomorphic" and expects everyone to automatically know what he is talking about when there is not even any reference to it on Wikipedia, etc.
 

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