Can 5-Dimensional Objects Exist Without 4-Dimensional Surfaces?

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Discussion Overview

The discussion explores the existence of 5-dimensional objects and the necessity of 4-dimensional surfaces or boundaries associated with them. It raises questions about the nature of dimensions, the definition of surfaces, and the implications of dimensionality in topological manifolds.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification
  • Mathematical reasoning

Main Points Raised

  • Some participants question whether 5-dimensional objects can exist independently of 4-dimensional surfaces, suggesting a potential need for dimensional reduction.
  • Others argue that a zero-dimensional manifold cannot have a boundary, raising questions about the implications for higher-dimensional objects.
  • There is a repeated inquiry into the definition of dimension and how one determines whether an object is 5-dimensional, 4-dimensional, or 6-dimensional.
  • Some participants propose that if an object is a 5-dimensional topological manifold, it can locally construct a 5-dimensional vector space, implying the existence of a 4-dimensional subspace.
  • Questions are raised about whether all x-dimensional topological manifolds necessarily have a (x-1) subspace, including for cases where x equals 1 or 0.

Areas of Agreement / Disagreement

Participants express differing views on the necessity of surfaces for higher-dimensional objects and the definitions of dimensions. The discussion remains unresolved, with multiple competing perspectives on these concepts.

Contextual Notes

Limitations include unclear definitions of dimensionality and the implications of boundaries in various dimensional contexts. The discussion does not resolve how dimensionality is determined or the conditions under which certain properties hold.

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Can there be a place(?) where only 5 dimesional object are allowed? Or would there always be the need for a 4 dimensional surface of the 5 dimensional obect?


If you'll always need to be able to subtract a dimension (the edge of a 2d plane is a 1d line and the end of a 1d line is a 0d point), would the surface of the zero dimensional "point" have a dimension of -1?
 
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Why does it need to have a "surface"? What's the surface of the sphere?

The boundary of a manifold can be empty, but if it exists, it has dimension one less. A zero-dimensional manifold can't have boundary, for obvious reasons.
 
Pjpic said:
Can there be a place(?) where only 5 dimesional object are allowed? Or would there always be the need for a 4 dimensional surface of the 5 dimensional obect?


If you'll always need to be able to subtract a dimension (the edge of a 2d plane is a 1d line and the end of a 1d line is a 0d point), would the surface of the zero dimensional "point" have a dimension of -1?

What is your definition of dimension? Ie., how are you able to determine that the object is 5 dimensional and not 4 dimensional or 6 dimensional?
If the object is a 5 dimensional topological manifold, then locally one can construct a 5-dimensional vector space; it is then trivial that there is a 4-dimensional subspace.
 
slider142 said:
What is your definition of dimension? Ie., how are you able to determine that the object is 5 dimensional and not 4 dimensional or 6 dimensional?
If the object is a 5 dimensional topological manifold, then locally one can construct a 5-dimensional vector space; it is then trivial that there is a 4-dimensional subspace.

I don't know how the number of dimensions is determined. Do all objects of x dimesional topological manifold have a (x-1) subspace? Would this be true for x =1? For x = 0?
 

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