# Thread: Notions of space and time in an Inflationary Multiverse

1. Member
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Aug 2010
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## Notions of space and time in an Inflationary Multiverse

It is said that if a person were able to float in rapidly expanding space and were able to observe a region of space dropping out of rapid expansion, then this person would see a bubble universe of finite size growing larger like a balloon being blown up.

However, for a person inside of the bubble universe, it is said that they would observe that the size of the universe is infinite.

At each moment of time, for the outside observer, the bubble universe would have a finite amount of space, while for the inside observer, there would appear to be an endless amount of space.

Why is it that an inside observer cannot see that their universe is in fact finite (at a moment of time) rather than appearing to be endless?

2. Originally Posted by tgoolsby2
It is said that if a person were able to float in rapidly expanding space and were able to observe a region of space dropping out of rapid expansion, then this person would see a bubble universe of finite size growing larger like a balloon being blown up.

However, for a person inside of the bubble universe, it is said that they would observe that the size of the universe is infinite.

At each moment of time, for the outside observer, the bubble universe would have a finite amount of space, while for the inside observer, there would appear to be an endless amount of space.

Why is it that an inside observer cannot see that their universe is in fact finite (at a moment of time) rather than appearing to be endless?
Do you have a reference for who said what?

Chris

3. I join csmyth in asking who said this.

Plus,

Originally Posted by tgoolsby2
...At each moment of time... at a moment of time...
Infinity is not a quantity or size. If you stop time for a moment and take account of your surroundings, nothing will be infinite. Infinity is always "adding one more" and never stopping. You can't do this when you freeze time.

Plus2, a person "floating in rapidly expanding space" would never be able to observe anything, since the space between him and anything else is expanding faster than light. No light could ever reach him.

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