# The entire universe rotates? **URL:** \ **Category:** Factual Questions\ **Created:** [July 8, 2025, 5:37pm UTC](https://boards.straightdope.com/t/the-entire-universe-rotates/1020634 "2025-07-08T17:37:34Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![OldGuy](https://avatars.discourse-cdn.com/v4/letter/o/3bc359/32.png) [@OldGuy](https://boards.straightdope.com/u/OldGuy)\ **Post date:** [July 8, 2025, 5:37pm UTC](https://boards.straightdope.com/t/the-entire-universe-rotates/1020634/1 "2025-07-08T17:37:34Z")
This article tries to explain the Hubble tension by saying the entire universe rotates very slowly. > **[A slowly spinning universe could solve the Hubble tension](https://phys.org/news/2025-04-slowly-universe-hubble-tension.html)** > > A new study in Monthly Notices of the Royal Astronomical Society by researchers including István Szapudi of the University of Hawaiʻi at Mānoa Institute for Astronomy suggests the universe may rotate—just extremely slowly. The finding could help... I understand that if the entire universe rotated there would be a centrifugal “force” that pushed the galaxies apart faster than otherwise. But what independent confirmation could there be that it was rotation causing it rather than just dark energy? And what the heck would it be rotating with respect to? My only thought is with respect to the universe beyond the observable universe. ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [July 8, 2025, 5:52pm UTC](https://boards.straightdope.com/t/the-entire-universe-rotates/1020634/2 "2025-07-08T17:52:08Z")
Earlier thread > [@The Universe is spinning](https://boards.straightdope.com/t/the-universe-is-spinning/1017408): > > According to this article, the universe may be spinning. Spinning with respect to what? It doesn’t seem there would be anything to measure the spin relative to so the only thing I can think of is there’s evidence of some kind of centrifugal force (which I can see might affect the measured Hubble constant). But how do you separate the notion of spin from the notion of a variable Hubble constant? ---
**Author:** ![engineer\_comp\_geek](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/engineer_comp_geek/32/504_2.png) [@engineer\_comp\_geek](https://boards.straightdope.com/u/engineer_comp_geek)\ **Post date:** [July 8, 2025, 5:55pm UTC](https://boards.straightdope.com/t/the-entire-universe-rotates/1020634/3 "2025-07-08T17:55:01Z")
Dr. Becky’s take on it (she’s an astrophysicist at the University of Oxford): [![](https://img.youtube.com/vi/ZuHqVqwssYQ/maxresdefault.jpg "Does the Universe SPIN once every 500 billion years?!") ](https://www.youtube.com/watch?v=ZuHqVqwssYQ) ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [July 8, 2025, 6:59pm UTC](https://boards.straightdope.com/t/the-entire-universe-rotates/1020634/4 "2025-07-08T18:59:10Z")
> [@OldGuy](#): > > But what independent confirmation could there be that it was rotation causing it rather than just dark energy? There would be a coriolis effect. ---
**Author:** ![CookingWithGas](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cookingwithgas/32/485_2.png) [@CookingWithGas](https://boards.straightdope.com/u/CookingWithGas)\ **Post date:** [July 9, 2025, 2:18pm UTC](https://boards.straightdope.com/t/the-entire-universe-rotates/1020634/5 "2025-07-09T14:18:04Z")
> [@OldGuy](#): > > But what independent confirmation could there be that it was rotation causing it rather than just dark energy? > > And what the heck would it be rotating with respect to? My only thought is with respect to the universe beyond the observable universe. I don’t know enough about dark energy to answer your first question, but you can determine if your frame of reference is rotating. An inertial frame of reference is one that is moving at a constant velocity. That velocity doesn’t have to be in relation to anything; it can zero, negative, or positive, depending on an arbitrary external frame of reference. The important thing is that Newton’s first law holds within the frame. If you are in an inertial frame, you can tell, but you can’t tell your velocity without an external reference. The Earth’s diameter is so large, we feel like we are sitting still but at the equator you would be moving at about 1000 miles per hour. However, you are actually going in a circle and can take measurements to demonstrate that you are actually in an accelerated frame (where the acceleration is a vector perpendicular to a tangent of your path and inwards towards the center). A rotating body rotates with respect to its center of rotation. You can take measurements to determine this without caring about anything external. We think of the Earth rotating with respect to its orbital path, or the Sun, or any other arbitrary celestial object, but if none of those things were available we could still determine that we were rotating. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [July 9, 2025, 3:29pm UTC](https://boards.straightdope.com/t/the-entire-universe-rotates/1020634/6 "2025-07-09T15:29:27Z")
> [@CookingWithGas](#): > > A rotating body rotates with respect to its center of rotation. You can take measurements to determine this without caring about anything external. We think of the Earth rotating with respect to its orbital path, or the Sun, or any other arbitrary celestial object, but if none of those things were available we could still determine that we were rotating. If it were not so, you could climb into a centrifuge and be immune to G-forces simply by declaring that it’s the rest of the universe spinning, while you stay still. ---
**Author:** ![Pardel-Lux](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pardel-lux/32/20182_2.png) [@Pardel-Lux](https://boards.straightdope.com/u/Pardel-Lux)\ **Post date:** [July 9, 2025, 3:43pm UTC](https://boards.straightdope.com/t/the-entire-universe-rotates/1020634/7 "2025-07-09T15:43:33Z")
The problem I have with a rotating universe is that if the universe is vast enough there comes a point where the universe rotates faster than the speed of light. And if the universe was infinite the speed of rotation would become infinite too. How do you avoid that? ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [July 9, 2025, 3:49pm UTC](https://boards.straightdope.com/t/the-entire-universe-rotates/1020634/8 "2025-07-09T15:49:26Z")
Are we talking about the universe rotating, or the _contents_ of the universe rotating? Your objection stands if the latter. But not the former. ---
**Author:** ![Lucas\_Jackson](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lucas_jackson/32/303_2.png) [@Lucas\_Jackson](https://boards.straightdope.com/u/Lucas_Jackson)\ **Post date:** [July 9, 2025, 7:30pm UTC](https://boards.straightdope.com/t/the-entire-universe-rotates/1020634/9 "2025-07-09T19:30:52Z")
> [@CookingWithGas](#): > > We think of the Earth rotating with respect to its orbital path, or the Sun, or any other arbitrary celestial object, but if none of those things were available we could still determine that we were rotating. How so? ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [July 9, 2025, 7:36pm UTC](https://boards.straightdope.com/t/the-entire-universe-rotates/1020634/10 "2025-07-09T19:36:34Z")
If you’re in a closed box that is moving perfectly smoothly in a straight line, you can’t do any experiment inside the box that would differentiate whether or not you are moving. If you’re in a closed box that is rotating, you only need to roll a marble on the floor of the box and observe whether it moves in a straight line relative to the floor of the box - if you’re rotating, it won’t. [![](https://img.youtube.com/vi/78Yymgk6qrM/maxresdefault.jpg "Coriolis Carousel: Demo") ](https://www.youtube.com/watch?v=78Yymgk6qrM) ---
**Author:** ![Lucas\_Jackson](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lucas_jackson/32/303_2.png) [@Lucas\_Jackson](https://boards.straightdope.com/u/Lucas_Jackson)\ **Post date:** [July 9, 2025, 7:58pm UTC](https://boards.straightdope.com/t/the-entire-universe-rotates/1020634/11 "2025-07-09T19:58:24Z")
Interesting, thanks. Another question: If the universe is rotating, doesn’t that imply there is a center? ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [July 9, 2025, 8:01pm UTC](https://boards.straightdope.com/t/the-entire-universe-rotates/1020634/12 "2025-07-09T20:01:17Z")
I think it does - assuming the rotation isn’t some weird chaotic thing that isn’t what we normally think of as geometric, concentric rotation, a rotating universe has to have a centre of rotation. ---
**Author:** ![CookingWithGas](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cookingwithgas/32/485_2.png) [@CookingWithGas](https://boards.straightdope.com/u/CookingWithGas)\ **Post date:** [July 9, 2025, 8:03pm UTC](https://boards.straightdope.com/t/the-entire-universe-rotates/1020634/13 "2025-07-09T20:03:58Z")
I wonder how there could be a center of rotation if there is no center of expansion, or a center in any other sense. ---
**Author:** ![OldGuy](https://avatars.discourse-cdn.com/v4/letter/o/3bc359/32.png) [@OldGuy](https://boards.straightdope.com/u/OldGuy)\ **Post date:** [July 9, 2025, 8:10pm UTC](https://boards.straightdope.com/t/the-entire-universe-rotates/1020634/14 "2025-07-09T20:10:58Z")
> [@Mangetout](#): > > If you’re in a closed box that is rotating, you only need to roll a marble on the floor of the box and observe whether it moves in a straight line relative to the floor of the box - if you’re rotating, it won’t. But rotating with respect to what? Locally we could say the Earth or the Sun or the galaxy. But if you mean the universe (and not the observable universe) then what do you measure the rotation with respect to. If the entire universe is rotating, doesn’t that mean there is no natural inertial frames of reference. You’d have to move in some fashion to counteract that. Also the Coriolis effect varies with the distance from the center. Does this mean there is a center of the universe, or is the universe’s rotation something like quantum spin which is not the same as rotation. Rather it is an intrinsic property of the universe and the same everywhere? ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [July 9, 2025, 8:11pm UTC](https://boards.straightdope.com/t/the-entire-universe-rotates/1020634/15 "2025-07-09T20:11:44Z")
It’s possible to have no centre of expansion if you have a grid of objects where the spaces between the objects is increasing at the same rate across the whole grid. You can pick a point and sit there and it will look like everything is going away from you, so you reason that you must be at the centre of expansion, but you can do that for any point and the experience will be the same there - therefore there is no definitive centre of expansion. Rotation simply doesn’t work like that. ---
**Author:** ![Pardel-Lux](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pardel-lux/32/20182_2.png) [@Pardel-Lux](https://boards.straightdope.com/u/Pardel-Lux)\ **Post date:** [July 9, 2025, 8:12pm UTC](https://boards.straightdope.com/t/the-entire-universe-rotates/1020634/16 "2025-07-09T20:12:02Z")
The center in how many dimensions? ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [July 9, 2025, 8:17pm UTC](https://boards.straightdope.com/t/the-entire-universe-rotates/1020634/17 "2025-07-09T20:17:07Z")
I think you’re conflating reference frames. I don’t know if this will help, but to expand on the previous examples: > [@Mangetout](#): > > If you’re in a closed box that is moving perfectly smoothly in a straight line, you can’t do any experiment inside the box that would differentiate whether or not you are moving. > > If you’re in a closed box that is rotating, you only need to roll a marble on the floor of the box and observe whether it moves in a straight line relative to the floor of the box - if you’re rotating, it won’t. If you’re in a closed box that is rotating **and is also moving perfectly smoothly in a straight line** , you can determine whether it is rotating by rolling a marble on the floor, but there is nothing you can do within the box to determine whether there is also a constant linear component to your motion. Rotation isn’t the same as motion at a constant velocity - The answer to ‘rotating relative to what?’ is ‘relative to **not rotating** ’ As above, if it were not so, you could get in a centrifuge and spin it up, and just declare the rest of the universe to be spinning wildly relative to yourself, and you should feel no G forces. That doesn’t happen. ---
**Author:** ![OldGuy](https://avatars.discourse-cdn.com/v4/letter/o/3bc359/32.png) [@OldGuy](https://boards.straightdope.com/u/OldGuy)\ **Post date:** [July 9, 2025, 9:45pm UTC](https://boards.straightdope.com/t/the-entire-universe-rotates/1020634/18 "2025-07-09T21:45:27Z")
OK let me ask the question this way. In the context of the universe rotating, presumably (ignoring my previously stated possibility that it’s like quantum spin) it must be that observers close to one another should detect rotation in the same direction and with the same angular velocity. On different sides of the center of rotation, the Coriolis force will move things in the opposite direction. So if we can find that, have found the center of the universe’s rotation? ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [July 9, 2025, 10:46pm UTC](https://boards.straightdope.com/t/the-entire-universe-rotates/1020634/19 "2025-07-09T22:46:48Z")
Yeah, I think you can probably derive the centre of rotation from measurements on one side only, assuming they’re sufficiently accurate. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [July 10, 2025, 1:00pm UTC](https://boards.straightdope.com/t/the-entire-universe-rotates/1020634/20 "2025-07-10T13:00:04Z")
If you had a universe where every object was fixed in place, but every individual object was rotating in the same direction, that would be a universe that rotates, but without having a discernible center. [Next page](https://boards.straightdope.com/t/the-entire-universe-rotates/1020634.md?page=2)