# The Naked Scientists Forum

### Author Topic: Is our universe bounded or infinite?  (Read 746 times)

#### ijaz

• Guest
##### Is our universe bounded or infinite?
« on: 06/12/2015 14:16:32 »
If the universe expands all the time it has to boundless but is there an upper bound or none whatsoever??

#### Don_1

• Neilep Level Member
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• A stupid comment for every occasion.
##### Re: Is our universe bounded or infinite?
« Reply #1 on: 06/12/2015 14:51:56 »
Our universe has a boundary only in that it ends where expansion ends. This 'boundary' is constantly expanding as the universe expands.
So what does it expand into? A limitless void. Boundless, infinite, call it what you will. Perhaps our universe will cease to expand when it reaches the point where there is no more dark matter to fill the spaces between the sub-atomic particles which are all that is left at the point of maximum expansion.
What then? My hypothesis is that all matter will then begin to collapse into a single point and whole process begins again.
As to 'maximum expansion', I think there will still be an infinite void beyond this point.

#### Space Flow

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##### Re: Is our universe bounded or infinite?
« Reply #2 on: 07/12/2015 06:01:52 »
Is our universe bounded or infinite?

This reads a bit like a trick question. It's not considered either of those.
The Universe is considered flat and unbounded in all 3 physical directions.
That is not the same as infinite. Any point anywhere has a coordinate value so it cant be bounded as a 1 can always be added so it also can't be infinite. You can say any direction tends to infinity, but that still is not infinite. At the same time it is not bounded.

Is that a fraction clearer than Mud?
« Last Edit: 07/12/2015 06:03:23 by Space Flow »

#### The Naked Scientists Forum

##### Re: Is our universe bounded or infinite?
« Reply #2 on: 07/12/2015 06:01:52 »