If the universe is finite in size, what is at the end of it?

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The discussion centers on the concept of a finite universe and the implications of its boundaries or edges. Participants argue that a finite universe does not necessarily imply an edge, drawing analogies to Earth, which is finite but lacks an edge. The conversation explores the idea of higher dimensions and how beings in lower dimensions might perceive their universe, suggesting that our understanding of the universe could be limited by our dimensional experience. Some contributors emphasize the importance of distinguishing between "boundary" and "edge" in this context. Ultimately, the question of what lies at the edge of a finite universe remains largely philosophical and speculative.
  • #51
nanosiborg said:
The way I'm using the term, our universe doesn't necessarily refer to everything.
The OP asked about the universe.
 
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  • #52
opposition in terms

There must be other, more nuanced and technical, meanings to 'finite' and/or to 'unbounded' because to us 99.9 percenters finite actually means bounded.
 
  • #53
That will be disconcerting news to racecar drivers...
 
  • #54
Finite in this context does not mean bounded, it means compact. Bounded only makes sense in metric spaces and in general relativity we do not have a natural metric to impose on arbitrary space-time solutions. It is true that a subset of ##\mathbb{R}^{n}## is compact iff it is bounded and closed but space-time manifolds are not naturally embedded in a higher dimensional euclidean space. We must make use of topological notions when looking at global characteristics hence the term "finite" (which I agree with you is a horribly ambiguous and non-technical term) refers to compactness. I should note that for arbitrary topological spaces, compactness does not always bear resemblance to the intuitive notion of finiteness; what it does allow us to do is to turn local properties of a topological space into a global property so in this way it codifies a sense of the space being "finite" in a loose sense.
 
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