Can rotation solve the Hubble Puzzle? • Hacker News Board

Re: Can rotation solve the Hubble Puzzle?

#31

Post by AnimalMuppet » Tue, Apr 22, 2025, 2:17 PM UTC

kstrauser wrote: post #27

lambdaone wrote: post #16

Earlier quoted context omitted.

Below the Planck distance, "closer" ceases to be a meaningful concept. Similarly, distances larger than the size of the observable universe may also be meaningless.

Why is that? I've heard this before but don't understand what it actually implies. Like, why can't 2 things meaningfully be half a Planck distance apart?

Imagine the universe is made out of graph paper, with only the points of intersection of the lines being actually "real". That is, space is actually discrete. If that is true, then you cannot meaningfully talk about things being "half a square" apart.

People (some people) think that the universe really is that way, at the Planck distance. Actual experimental confirmation is somewhat lacking at this time...

Re: Can rotation solve the Hubble Puzzle?

#32

Post by [deleted] » Tue, Apr 22, 2025, 2:21 PM UTC

iainmerrick wrote: post #22

ziddoap wrote: post #21

Earlier quoted context omitted.

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)

This comment has a good summary of the debunking: https://news.ycombinator.com/item?id=43540635 It's unfortunately rare for this kind of straightforward falsification to make it into publications aimed at the general reader. "A lie is halfway round the world before the truth has got its boots on," as they say.

[deleted]

Re: Can rotation solve the Hubble Puzzle?

#33

Post by ben_w » Tue, Apr 22, 2025, 2:27 PM UTC

voidUpdate wrote: post #15

jl6 wrote: post #12

Earlier quoted context omitted.

That’s one speculative possibility, but we don’t know. It could be infinite, or finite with a boundary just out of sight (beyond the edge of the observable universe), or some other more exotic geometry. There’s no solid evidence either way. My money’s on non-infinite, just because I’m not sure infinity is a well-defined concept outside of mathematics. We’ve certainly never observed any other infinite phenomena.

It's only been a finite time since the universe was very small, so unless it's expanding infinitely fast, I don't see how it could be infinite

It's (mathematically) allowed for it to have always been infinite, and still grow.

If you take the number like and apply f(x) = 2x, it was infinite before and after.

Re: Can rotation solve the Hubble Puzzle?

#34

Post by voidUpdate » Tue, Apr 22, 2025, 2:30 PM UTC

ben_w wrote: post #33

voidUpdate wrote: post #15

Earlier quoted context omitted.

It's only been a finite time since the universe was very small, so unless it's expanding infinitely fast, I don't see how it could be infinite

It's (mathematically) allowed for it to have always been infinite, and still grow. If you take the number like and apply f(x) = 2x, it was infinite before and after.

yes but if x is finite, any f(x) will still be finite. So the universe has either always been finite, or always been infinite, and given that it started out being very small in a big bang, it would imply the former

Re: Can rotation solve the Hubble Puzzle?

#35

Post by BigParm » Tue, Apr 22, 2025, 2:37 PM UTC

est31 wrote: post #4

> 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.…

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

Re: Can rotation solve the Hubble Puzzle?

#36

Post by lumost » Tue, Apr 22, 2025, 2:38 PM UTC

voidUpdate wrote: post #34

ben_w wrote: post #33

Earlier quoted context omitted.

It's (mathematically) allowed for it to have always been infinite, and still grow. If you take the number like and apply f(x) = 2x, it was infinite before and after.

yes but if x is finite, any f(x) will still be finite. So the universe has either always been finite, or always been infinite, and given that it started out being very small in a big bang, it would imply the former

not if x is the set of all Real numbers. All points could have been infinitely close to each other at the big bang, and the universe could still have been infinite in size.

Re: Can rotation solve the Hubble Puzzle?

#37

Post by shermantanktop » Tue, Apr 22, 2025, 2:39 PM UTC

theoreticalmal wrote: post #10

exe34 wrote: post #9

Earlier quoted context omitted.

and we would be at the center?

My dog is quite sure she’s at the center, if we’re trying to be specific

Main Character Energy? My cat has that too.

Re: Can rotation solve the Hubble Puzzle?

#38

Post by irrational » Tue, Apr 22, 2025, 2:50 PM UTC

BigParm wrote: post #35

est31 wrote: post #4

> 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.…

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

And an axis.

Re: Can rotation solve the Hubble Puzzle?

#39

Post by daxfohl » Tue, Apr 22, 2025, 2:53 PM UTC

kstrauser wrote: post #27

lambdaone wrote: post #16

Earlier quoted context omitted.

Below the Planck distance, "closer" ceases to be a meaningful concept. Similarly, distances larger than the size of the observable universe may also be meaningless.

Why is that? I've heard this before but don't understand what it actually implies. Like, why can't 2 things meaningfully be half a Planck distance apart?

The only reason I've heard that isn't super handwavy is that measuring it would require a wavelength with enough energy to create a black hole. IDK if that's true or not, and IDK if that also means the distance doesn't exist or if it's just not measurable.

I've also heard that there's nothing special about planck length other than it being universal constant that we and any conceivable aliens would agree on as a standard of measure. So, idk.

Re: Can rotation solve the Hubble Puzzle?

#40

Post by ben_w » Tue, Apr 22, 2025, 2:53 PM UTC

voidUpdate wrote: post #34

ben_w wrote: post #33

Earlier quoted context omitted.

It's (mathematically) allowed for it to have always been infinite, and still grow. If you take the number like and apply f(x) = 2x, it was infinite before and after.

yes but if x is finite, any f(x) will still be finite. So the universe has either always been finite, or always been infinite, and given that it started out being very small in a big bang, it would imply the former

> yes but if x is finite, any f(x) will still be finite.

The number line is not finite, even though every value on it is. The universe may be like the number line.

> and given that it started out being very small in a big bang, it would imply the former

The universe started out denser, which is not quite the same as "small" when talking about infinities. The currently visible universe gets both things at the same time, but only because the visible bit is finite.

Apply f(x) = x * 1e-60 to the number line, and things which were previously spaced out every integer, are now much more densely packed, but the number line as a whole is still the same size — infinite.