1100 gamma ray bursts a day on Earth!

[mistermack]

This is the crux of your misunderstanding. You appear to view the universe as a 3-dimensional spheroid, with a definite centre and an edge. This is NOT the consensual view of things. "Finite but unbounded" is the phrase you will come across if you read up on the shape of the universe. Start here https://en.wikipedia.org/wiki/Shape_of_the_universe

You're putting words in my mouth there. I don't have a view of the universe, except a wait-and-see view.
But that page on the shape of the universe isn't relevant because it's not about the "shape" in the normal sense. It's about the overall curvature of space time.

In that sense, a perfectly spherical universe in 3d terms could be perfectly flat in the terms that they are talking about.

[Hermit]

Galaxies spin, stars spin, and planets spin. So, why not the whole universe?

If the universe spun, it would have to spin relative to something outside the universe, no?

[pErvinalia]

I wonder. The universe expands, but that doesn't need to be in relation to anything outside the universe. It's in relation to the size of it at t-1.

[Xamonas Chegwé]

I wonder. The universe expands, but that doesn't need to be in relation to anything outside the universe. It's in relation to the size of it at t-1.

But it can't spin relative to itself. Or move at all relative to itself. Only relative to something "outside".

[MiM]

But then it cannot expand relative to itself, either. Which only can mean one thing. We are all shrinking.

[Xamonas Chegwé]

But then it cannot expand relative to itself, either. Which only can mean one thing. We are all shrinking.

Of course it can!

Think of the balloon analogy. As a balloon inflates, its surface area grows and the distances between points on that surface increases. This can be measured from a point on the surface. However, whether the balloon is spinning or not can only be measured either externally, or relative to an observable, external point.

[MiM]

I still claim that (size of universe)/(size of universe)=1. Or if it doesn't now, it never has and never will.

But to be more serious. What if you would be able to measure a centripetal force in the universe? Would that not indicate that it is rotating? The same way as measuring growing distances indicates it is growing?

[Brian Peacock]

OK guys, so what does all this mean for the newly-named Hulkon particles.

[Xamonas Chegwé]

OK guys, so what does all this mean for the newly-named Hulkon particles.

They are probably, or probably not, green.

[mistermack]

Galaxies spin, stars spin, and planets spin. So, why not the whole universe?

If the universe spun, it would have to spin relative to something outside the universe, no?

Depends what you mean by universe.
When something spins, it's parts constantly accelerate towards the axis of rotation.
A force is needed to cause that acceleration, and in solid objects, that's provided by the molecular bonds of particles, and in something like a galaxy, it's provided by the gravity of the entire galaxy acting on it's parts.

These forces are a sign of spinning, as well as the Coriolis effect in which objects travel in a curve when released, relative to the spin of the object.

These effects aren't there because you are spinning relative to something outside you. They are there because you are spinning relative to the space that you inhabit.
If you were spinning, and the space you occupy is spinning at the same rate, there would be no physical forces or Coriolis effect and the only way you could tell, would be to look at the things around you.

When it comes to the universe spinning, they aren't talking about spacetime spinning with it. If it was, then nothing would be spinning. They mean the matter and energy that makes up the universe spinning, relative to the static space time. Just like you spinning.
So, I think the answer is no to your question. The universe wouldn't have to spin relative to something outside. It would spin relative to the spacetime INSIDE.

Spacetime can't spin, because gravity doesn't affect it, so there is no known force that can make it spin. Spactime spinning would be a meaningless concept.

[mistermack]

bollicks failed edit

[Hermit]

Galaxies spin, stars spin, and planets spin. So, why not the whole universe?

If the universe spun, it would have to spin relative to something outside the universe, no?

Depends what you mean by universe.

My definition is the traditional one: Everything there is. By that definition there is nothing outside the universe, including spacetime.

[mistermack]

Galaxies spin, stars spin, and planets spin. So, why not the whole universe?

If the universe spun, it would have to spin relative to something outside the universe, no?

Depends what you mean by universe.

My definition is the traditional one: Everything there is. By that definition there is nothing outside the universe, including spacetime.

I think you missed the point I made in that post.
If by the universe, you mean the matter, energy AND spacetime that it occupies, then to say "spinning universe" is meaningless. It's not spinning.

If you mean all the matter and energy is spinning, but the spacetime is not, then that could be detected internally, by observing the alteration in the course of moving objects due to the Coriolis effect. Although it would be tiny by now, after 14 odd billion years of expansion.

On Earth, the Coriolis effect causes spin in weather systems. They have clockwise and anticlockwise rotation, depending on whether it's in the North, or South.

That's the point that the study was making about the spin of the galaxies being not as expected.
It could be a sign of a spinning universe.

[JimC]

The universe spins if I slightly overdo the gin...