What Geometry Emerges from a Non-Standard Induced Connection?

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Discussion Overview

The discussion revolves around the geometry that emerges from using a non-zero transverse vector field for projection in the context of a hypersurface in Euclidean space, as opposed to the standard Levi-Civita connection. Participants explore the implications of this approach on the induced geometry, including questions of compatibility and torsion.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant describes how a hypersurface obtains its Levi-Civita connection through orthogonal projection of vector fields and proposes using a non-zero transverse vector field instead.
  • Another participant expresses the need for calculations to determine the nature of the geometry induced by the non-standard projection and requests a worked-out example.
  • A different participant agrees to attempt constructing an example on the sphere and questions whether the resulting geometries would be torsion-free.
  • One participant compares the proposed method to pulling back the Levi-Civita connection for a different metric on R^3, suggesting that the outcome may depend on the nature of the pullback metric.
  • Another participant asserts confidence that the resulting geometry would be torsion-free.

Areas of Agreement / Disagreement

Participants express differing views on the implications of using a non-zero transverse vector field, with some questioning the compatibility of the induced geometry and others asserting it would be torsion-free. The discussion remains unresolved regarding the specific nature of the geometry that emerges.

Contextual Notes

Participants note the need for calculations and examples to clarify the implications of their ideas, indicating that assumptions about the nature of the vector field and the resulting geometry are not fully explored.

lavinia
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A hypersurface of Euclidean space obtains its Levi-Civita connection by orthogonal projection
of ordinary derivatives of vector fields in Euclidean space onto the hypersurface's tangent space.

Suppose rather than the unit normal, there is a non-zero transverse vector field and orthogonal projection is replaced by projection with respect to this vector field. What sort of geometry comes from this?
 
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I'm afraid we need to calculate to say what happens ( or even whether a compatible geometry is induced by such a field). Could you share a worked-out example?
 
Eynstone said:
I'm afraid we need to calculate to say what happens ( or even whether a compatible geometry is induced by such a field). Could you share a worked-out example?

It was just an idea but sure I will try to construct an example on the sphere and get back to you.

I wonder if these geometries are even torsion free.
 
Hmm, how is this any different than pulling back the Levi-Civita connection for a different metric on R^3? I.e. if I declare the vector field to be orthogonal to the tangent space of the sphere, you would be getting a (perhaps different) Riemannian connection. Whether it's the Riemannian connection for the round metric on S^2 depends on whether the pullback metric is the same.
 
In any event, I'm quite certain it would be torsion-free.
 

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