Can rotation solve the Hubble Puzzle?

https://academic.oup.com/mnras/article/538/4/3038/8090496?login=false

by toss1 • 1 year ago

73 113 1 year ago

academic.oup.com

hoseja• 1 year ago

Wait did nobody seriously consider rotation yet? Everything is rotating. Angular momentum is conserved.

jvanderbot• 1 year ago

Isotropy is a fundamental assumption that is very hard to let go of.

exe343• 1 year ago

Where would the axis of rotation be?

gitaarik7• 1 year ago

https://en.m.wikipedia.org/wiki/Axis_of_evil_(cosmology)

nodfyr• 1 year ago

That would imply a preferred direction in the universe (the axis of rotation) and thus anisotropy.

There are stringent constraints on anisotropy from the cosmic microwave background.

In particular, one can use the Doppler effect to check whether the CMB dipole is compatible with our velocity with respect to the CMB frame.

gitaarik7• 1 year ago

Well, the universe has an axis, found in the CMB:

https://en.m.wikipedia.org/wiki/Axis_of_evil_(cosmology)

lumost2• 1 year ago

Rotation implies a great many observables and properties of the universe. There would be a cosmic axis, which implies a cosmic center and a cosmic north. Both concepts that are problematic in an infinite universe. If the universe is in fact inside of a black hole of a different universe - some of these problems go away as the Hubble volume would be the finite boundary of the universe.

exe343• 1 year ago

and we would be at the center?

AnimalMuppet4• 1 year ago

Are we in an infinite universe? I thought the current thinking was that it was finite but unbounded; that is, that it curved back on itself.

Galatians4_16• 1 year ago

If the universe is in fact inside of a black hole of a different universe

The observation could also be due to an area of relatively high density inside an area of relatively no density.

TheRealPomax2• 1 year ago

Except why would there only be one axis?

est31• 1 year ago

All objects within our universe rotate, including planets, stars, solar systems, galaxies, and galaxy clusters. Moreover, black holes, spherically symmetric objects with horizons, display near maximal rotation as presented by Daly (2019). The idea that everything revolves [...] naturally extends to the whole universe, as hinted by recent claims of anisotropic Hubble expansion in X-ray observations by Migkas et al. (2021). Furthermore, a plausible syllogism is that the universe has near-maximal rotation, motivated by cosmologies where the universe is the interior of a black hole (Pathria 1972).

BigParm• 1 year ago

If spacetime rotates, does that imply there being a centre of the universe?

irrational• 1 year ago

And an axis.

pmontra• 1 year ago

Wouldn't the center be the Big Bang and the 3D Universe at the current time (if Relativity lets me write about a current time) be the 3D surface of the 4D sphere (or spheroid) that the Big Bang is creating by keeping to expand?

layer86• 1 year ago

If the universe is the interior of a black hole, one would assume so.

olddustytrail3• 1 year ago

Depends what you mean by centre, I guess.

If you have two stars orbiting each other, they orbit a centre of gravity and they will probably both be rotating in the same direction as their orbits.

Is that a meaningful centre for anything else though?

sandworm101• 1 year ago

There is. The center of the observable universe is earth. Every alien civilization will see themselves at the center of thier observable universe. And each will observe the same rotation in faraway objects. Relativity makes things strange.

altcognito• 1 year ago

If everything started from a singularity that had a axiomatically uniform rotation, you might not be able to assess the center "axis" based from inside spacetime itself

tatjam• 1 year ago

This seems to be a variation of Mach's principle, which is one of the closest things to philosophy in physics!

To say that the universe rotates usually implies that it rotates with respect to something external. If we limit ourselves to the visible universe, this would mean that mass outside our light cones can actually influence us, by means of building the frame of reference that allows us to say that the universe rotates!

jfengel4• 1 year ago

Yes, it would. Or at least a central axis.

Which would undercut practically all of modern physics. Really fundamental conservation laws like momentum and energy rely on the universe being equal in all directions. If it has a central axis, that does not hold.

So if that holds, it's potentially a major pointer to the very origins of the universe itself. But it's also one of those extraordinary claims that require extraordinary proof. I strongly doubt that this will stand up to scrutiny -- though I'll certainly be pleased if it turns out be true, because that will be a major advance in our understanding.

cryptonector3• 1 year ago

a plausible syllogism is that the universe has near-maximal rotation

And also from the abstract:

Curiously, this is close to the maximal rotation, avoiding closed time-like loops with a tangential velocity less than the speed of light at the horizon.

That's weird considering that in lambda CDM the universe's accelerating expansion implies that stuff falls out of our observable universe, which implies that there is more stuff beyond the edge of the observable universe, and anyways there is no center of the universe and we are only at the center of our observable universe, which also further implies that there is stuff beyond the observable universe. Are they saying that our observable universe has a rate of rotation such that the tangential velocity at the edge is about the speed of light? What about the stuff beyond the edge? And as u/BigParm wonders, doesn't having the whole universe rotate imply a center? Surely we can't be at that center. But maybe there can be an illusion that we are at the center of rotation.

ano-ther• 1 year ago

If the universe is a black hole, would we be able to see anything falling into it after it crosses the event horizon?

consp• 1 year ago

You must be able to observe the edge to see that. And afaik the scientific community agrees no edge is observable in our cone of light.

ashoeafoot• 1 year ago

So everything that ever fell into the blackhole arrives into the big bang at the start?

bostonwalker• 1 year ago

I seem to recall there was an article posted here recently which noted that galaxies have a preferred direction of rotation. Seems like the universe itself rotating could be a reason why?

dkural2• 1 year ago

That article is by a crank. People pointed out that he cherry-picked the galaxies, and no one else who looked at the data objectively saw any evidence of preference for a rotation direction.

ziddoap3• 1 year ago

I looked around (Smithsonian, space.com, astronomy.com, etc.), but nowhere has any mention of people disputing the findings, do you have a link? Who is "people" in this case?

(I was/am skeptical just because it's a single-author study with pretty spectacular results, and have been keeping an eye out for any followups, but must have missed them)

roarkeful• 1 year ago

The universe being a giant toilet in the process of flushing is delightfully Doug Adams inspired.

ForOldHack3• 1 year ago

It's that constant sucking sound ...

BurningFrog2• 1 year ago

If I understand what I skimmed, the idea is that space-time itself rotates, not all the collective matter in it?

jfengel4• 1 year ago

Correct. Though the matter in it would also move, dragged along by the space-time.

It's much like the expansion of the universe, which is separate from the ordinary momentum of the objects within the universe. But the objects within the universe do move apart along with it.

BurningFrog2• 1 year ago

Thanks.

These things really challenge my physics intuition!

daxfohl4• 1 year ago

ICYMI: a slick link from the article with a video that demonstrates how closed timelike curves work in Godel's time traversal solution to Einstein's field equations. https://iopscience.iop.org/article/10.1088/1367-2630/15/1/01...

WhitneyLand• 1 year ago

“We show that a Gödel inspired slowly rotating dark-fluid variant of the concordance model resolves this tension…”

Gödel wait what? I thought of him as “only” the logician who killed Hiblert’s dreams and caused people to question the very foundations of mathematics.

Dude then took up physics as a hobby and trolled Einstein by discovering closed time-like curves?

layer86• 1 year ago

At the level of what he did, physics is “just” math (finding solutions for Einstein’s general-relativity equations).

Also, from Wikipedia: “At age 18 [so around 1924], Gödel joined his brother at the University of Vienna. He had already mastered university-level mathematics. Although initially intending to study theoretical physics [we can assume that’d include an interest in relativity at that time], he also attended courses on mathematics and philosophy.”

daxfohl4• 1 year ago

Godel and Einstein were actually quite close.

mcswell2• 1 year ago

There's a scene in the recent movie Oppenheimer about that.

TheRealPomax2• 1 year ago

If your paper has a question title, it should be sent back to you with the note "change the title to summarize the paper".

IAmBroom• 1 year ago

And Betteridge's Law applies, so based on this alone: the Universe does not rotate.

jinwoo682• 1 year ago

Universe is called universe because it is the only one. Everything that exists should be part of the universe. When we say the universe rotates, what does it mean? Rotate relative to what? Does it mean that there's a larger "universe" that contains ours?

layer86• 1 year ago

“Universe” is often used in the sense of “observable universe”.

jinwoo682• 1 year ago

I don't think the paper claims that it's the observable universe that rotates. Does it? It'd be awkward if only the observable universe rotates. Observable universe is not special. It's observable just because it is "close" to the Earth.

olddustytrail3• 1 year ago

Rotation isn't relative. You can tell how quickly you're rotating without reference to any other objects.

carra• 1 year ago

But even then you can only tell that you are rotating relative to space itself. If I understand correctly here we are speaking about the space itself rotating, so that would not be possible unless something else contains our universe's space, right?

philipswood• 1 year ago

Nitpick: "Atoms are called atoms because they have no subdivisible parts".

Oops, it turns out we used the name too soon.

When people say "universe" these days they mean the "visible universe" (or maybe the visible universe plus the stuff we're sure is there, but that falls outside our light cone now) - and not the original definition of the word anymore.

(Not that we have "found" anything else yet.)

cryptonector3• 1 year ago

Nitpick: atoms really have no subdivisible parts with the same properties as the whole.

They are aptly named.

natch2• 1 year ago

Rotation relative to what?

analog31• 1 year ago

I consider this to be a good question, but with a reasonably familiar answer:

Rotation is absolute. Unlike linear motion, you can tell if you're sitting in a rotating frame of reference or not. Experiments such as the Coriolis force, and Foucault's pendulum, are demonstrations of this principle.

In fact, a historical oddity is that when this idea was nailed down by both theory and experiment, the Catholic Church dropped its ban on heliocentrism. (Not that it mattered, the horse had already left the barn).

natch2• 1 year ago

Thanks! That makes sense, but didn't come to mind right away for some reason.

randomcarbloke• 1 year ago

based on napkin math, the rotation they land on: 4.34 x 10^-20 rad/s is one order of magnitude (not a lot on a cosmological scale) slower than necessary for a causal disconnect at the boundary of the observable universe due to tangential velocity (at ~C) - obviously my maths could be off-by-one.

Is this a reasonable conclusion?

sojuz151• 1 year ago

And the Hubble tension is around 4%, within a factor of 2 of that 10%. This sounds reasonable.

Can rotation solve the Hubble Puzzle?

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