Any surface bounded by the same curve in Stokes' theorem

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Discussion Overview

The discussion revolves around the asymmetry observed in Stokes' theorem compared to Gauss' theorem, particularly focusing on the uniqueness of volumes bounded by surfaces in three-dimensional space. Participants explore the implications of this asymmetry in the context of differential geometry and calculus.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants note that in ##\mathbb{R}^3##, a 2D surface uniquely bounds a volume, which is a characteristic feature of this space.
  • Others argue that the general Stokes formula, ##\int_{\partial M}\omega=\int_Md\omega##, is symmetric and does not depend on the embedding of the manifold ##M##.
  • A participant questions whether the uniqueness of the volume relates to the triviality of homology in ##\mathbb{R}^3##.
  • There is a request for an explanation of the asymmetry in simpler calculus terms, with an analogy to living in different dimensional spaces.
  • Another participant suggests that in a 2D world, only one 2D volume can be enclosed by a closed curve, while in 3D, multiple surfaces can be associated with the same curve.
  • A participant proposes a scenario where a 2D surface could enclose multiple 3D volumes, considering both the inside and outside of a cavity as analogous to a 1D curve enclosing multiple 2D surfaces.

Areas of Agreement / Disagreement

Participants express various viewpoints regarding the uniqueness of volumes and the implications of dimensionality, indicating that multiple competing views remain without a consensus.

Contextual Notes

Some discussions involve assumptions about the nature of surfaces and volumes in different dimensions, as well as the implications of the general Stokes formula across various mathematical contexts.

feynman1
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In Stokes' theorem, the closed line integral of f=the surface integral of curl f on ANY surface bounded by the same curve. But in Gauss' theorem, the surface integral of f on a surface=the volume integral of div f on a unique volume bounded by the surface. A surface can only enclose 1 volume whereas a curve can enclose many surfaces. So why is the asymmetry?
 
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it is because in ##\mathbb{R}^3## if a 2D surface bounds some volume then this volume is unique. It is just a feature of ##\mathbb{R}^3##. The general Stokes formula ##\int_{\partial M}\omega=\int_Md\omega## is symmetric. And the manifold ##M## is not obliged to be embedded anywhere
 
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wrobel said:
it is because in ##\mathbb{R}^3## if a 2D surface bounds some volume then this volume is unique. It is just a feature of ##\mathbb{R}^3##. The general Stokes formula ##\int_{\partial M}\omega=\int_Md\omega## is symmetric. And the manifold ##M## is not obliged to be embedded anywhere
I'm curious on this property of ##\mathbb R ^3##. Do you mean that its homology is trivial?
 
wrobel said:
it is because in ##\mathbb{R}^3## if a 2D surface bounds some volume then this volume is unique. It is just a feature of ##\mathbb{R}^3##. The general Stokes formula ##\int_{\partial M}\omega=\int_Md\omega## is symmetric. And the manifold ##M## is not obliged to be embedded anywhere
Could you please explain why this asymmetry (1D-2D and 2D-3D) is in the language of calculus or on a similar level?
 
feynman1 said:
Could you please explain why this asymmetry (1D-2D and 2D-3D) is in the language of calculus or on a similar level?
If you live in 2d world there only one 2d-volume is contained inside a loop of a closed curve. But if you exit in 3d then you see that there are a lot of two dimensional films pulled up on this curve. The same if you come out from ##\mathbb{R}^3## to ##\mathbb{R}^4##. The general Stokes formula does not care in which ##\mathbb{R}^m## you live and which metric you use to consider vectors instead of differential forms. Have a patience it will be explained in more advanced courses later
 
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wrobel said:
If you live in 2d world there only one 2d-volume is contained inside a loop of a closed curve. But if you exit in 3d then you see that there are a lot of two dimensional films pulled up on this curve. The same if you come out from ##\mathbb{R}^3## to ##\mathbb{R}^4##. The general Stokes formula does not care in which ##\mathbb{R}^m## you live and which metric you use to consider vectors instead of differential forms. Have a patience it will be explained in more advanced courses later
I can think of only 1 possibility where a 2d surface can enclose multiple 3d volumes: the 3d volume inside or that outside (cavity). Does that count as an analogue of 1d curve enclosing multiple 2d surfaces?
 
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