# How big is the known universe?

**URL:** <https://boards.straightdope.com/t/how-big-is-the-known-universe/602920>\
**Category:** Factual Questions\
**Created:** [November 14, 2011, 6:32pm UTC](https://boards.straightdope.com/t/how-big-is-the-known-universe/602920 "2011-11-14T18:32:07Z")\
**Posts on this page:** 3\
**Page:** 3

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**Author:** ![Farmer\_Jane](https://avatars.discourse-cdn.com/v4/letter/f/bbe5ce/32.png) [@Farmer\_Jane](https://boards.straightdope.com/u/Farmer_Jane)\
**Post date:** [November 17, 2011, 12:07am UTC](https://boards.straightdope.com/t/how-big-is-the-known-universe/602920/42 "2011-11-17T00:07:38Z")

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My son asked me this q. Not only did I not know how to answer, but how do you explain ‘light years’ to a kid?

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**Author:** ![Candyman74](https://avatars.discourse-cdn.com/v4/letter/c/ad7895/32.png) [@Candyman74](https://boards.straightdope.com/u/Candyman74)\
**Post date:** [November 17, 2011, 12:32am UTC](https://boards.straightdope.com/t/how-big-is-the-known-universe/602920/43 "2011-11-17T00:32:18Z")

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> [@CitizenPained](#):
>
> but how do you explain ‘light years’ to a kid?

The distance light travels in a year?

Dunno. How old is your son?

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**Author:** ![Naxos](https://avatars.discourse-cdn.com/v4/letter/n/50afbb/32.png) [@Naxos](https://boards.straightdope.com/u/Naxos)\
**Post date:** [November 17, 2011, 4:56am UTC](https://boards.straightdope.com/t/how-big-is-the-known-universe/602920/44 "2011-11-17T04:56:38Z")

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> [@Chronos](#):
>
> The age of the Universe is how long the Universe _has_ existed, not how long it _will_ exist.

If I may interject a couple somewhat related questions here…

Recently there were reports that the oldest observable object we can observe is 13.1 billion light years away. Which means that light started travelling from that object towards “us” 13.1 billion years ago.

Did the area in time/space Earth now occupies existed 13.1 billion years ago?

The immediate answer that comes to mind is no. So the universe must have expanded at an immense fast rate - probably what inflation theory is all about - and now is expanding at least as fast and probably faster than the speed of light.

Is it at all possible that the space/time area that Earth occupies now did exist, maybe folded within the state or dimensions of the universe which has now unfolded, or expanded, so that the light from the 13.1 bly away object can now reach Earth?

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