# If the universe is expanding...

**URL:** <https://boards.straightdope.com/t/if-the-universe-is-expanding/253785>\
**Category:** Factual Questions\
**Created:** [July 6, 2004, 3:05pm UTC](https://boards.straightdope.com/t/if-the-universe-is-expanding/253785 "2004-07-06T15:05:24Z")\
**Posts on this page:** 3\
**Page:** 2

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**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\
**Post date:** [July 8, 2004, 2:47am UTC](https://boards.straightdope.com/t/if-the-universe-is-expanding/253785/21 "2004-07-08T02:47:31Z")

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**1010011010** , that ring of galaxies with low relative velocities you mentioned would be spread across half the sky, and have members at vastly different distances (depending on their coordinates in the celestial sphere) as determined by angular size or nova brightness etc. That’s not the way the sky looks.

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**Author:** ![1010011010](https://avatars.discourse-cdn.com/v4/letter/1/ea666f/32.png) [@1010011010](https://boards.straightdope.com/u/1010011010)\
**Post date:** [July 8, 2004, 3:29am UTC](https://boards.straightdope.com/t/if-the-universe-is-expanding/253785/22 "2004-07-08T03:29:36Z")

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> [@Squink](#):
>
> That’s not the way the sky looks.

I realized that, which is why I had babble mode on. It’s still an interesting twist on the “expanding in all directions” explanation. Could be that we have both a general uniform expansion and the spherical expansion at the same time? I’m not sure what that would look like in the sky, though… or really even what we would be looking FOR, if that were the case (probably still the ring of slightly less redshifted galaxies?)

It would also depend on the shape of the universe, though… it could be the uniformity of the expansion is because of a hall of mirrors type effect… seeing snapshots of the same space from many times, as the light takes different routes through space to get to us. And it’s giving me a headache trying to think what we might expect if the universe is shaped like a torus.

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**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\
**Post date:** [July 8, 2004, 4:48am UTC](https://boards.straightdope.com/t/if-the-universe-is-expanding/253785/23 "2004-07-08T04:48:33Z")

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> [@](#):
>
> Could be that we have both a general uniform expansion and the spherical expansion at the same time? I’m not sure what that would look like in the sky

As soon as you add expansion away from a fixed point, as from an explosion, you end up with all sorts of geometric effects on the red shift. For example, looking towards the center of the explosion from the milky way, you might see a Hubble-like increase in redshift with distance up until you started looking at galaxies on the _other side of the center_. The outward velocity of those galaxies would **add** to our own outward velocity thus causing redshift to increase more sharply with distance past the center.

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