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

  • Thread starter Kutt
  • Start date
The way I'm using the term, our universe doesn't necessarily refer to everything.
The OP asked about the universe.
 
234
1
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.
 

russ_watters

Mentor
18,645
4,879
That will be disconcerting news to racecar drivers...
 

WannabeNewton

Science Advisor
5,774
526
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.
 

Related Threads for: If the universe is finite in size, what is at the end of it?

Replies
50
Views
8K
Replies
24
Views
3K
E
Replies
37
Views
3K
  • Posted
Replies
3
Views
2K
R
  • Posted
Replies
23
Views
3K

Physics Forums Values

We Value Quality
• Topics based on mainstream science
• Proper English grammar and spelling
We Value Civility
• Positive and compassionate attitudes
• Patience while debating
We Value Productivity
• Disciplined to remain on-topic
• Recognition of own weaknesses
• Solo and co-op problem solving

Hot Threads

Top