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Old 21-09-2013, 10:08 AM
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sjastro
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Quote:
Originally Posted by Steffen View Post
I agree. A finite universe is impossible to imagine. One immediately wonders, what's on the other side of the boundary? What's the thing called in which the finite universe bubble is suspended? The only intuitively possible universe is an infinite one for me.

Cheers
Steffen.
Perhaps this will help.

Your shadow is a 2-D object projected onto a surface.
The term dimension refers to degrees of freedom. 2 D space means an object can move in terms of "length" and "width", 3-D space an object can move in terms of "length" "width" and "height".

Your shadow is constrained to the intrinsic geometry of the surface.
It can't jump off the surface hence it cannot perceive a boundary with the surrounding extrinsic geometry of space. Since the surface is finite (in this case the surface of the Earth), the shadow's Universe is in fact finite.

Its tempting to take this analogy too far by claiming our Universe is expanding into higher dimensional space. The problem is our mathematical models are based on the intrinsic geometry of the Universe, there is no "outside" or "boundary". Besides there is no evidence to support the Universe expanding into an existing space.

Regards

Steven
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