Does our universe have "spin"

[Catastrophe]

Does our universe have "spin"

Let us put this to bed. if possible.

If the Universe is "all there is", then there is nothing "external" with which to observe/comprehend spin.

If anyone is using different ground terminology, such as using a definition such as actually "part of something else", e.g., one of several similar "universes", then these other "universes" can have spin relative to each other.

We cannot hold a discussion with conflicting definitions.

OP, do you want to end this before we get into another mess of conflicting mutually incongruent babbles?

Cat

 

[Unclear Engineer]

Getting back to my question thread after being away for a while, I see that the link Cat provided shows that some others have taken this question seriously enough to have tested for spin in the universe, and have not found any - with enough sensitivity to say the odds are "only a 1 in 121,000 chance that the universe is not the same in all directions." Unfortunately, a subscription is required to read how they did the test. But, I think this does answer my question to the extent that we can answer it now. The question is not being ignored, and the tests to date indicate no discernable spin.

The abstract for the paper referenced by the article gives a little more detail:
"A fundamental assumption in the standard model of cosmology is that the Universe is isotropic on large scales. Breaking this assumption leads to a set of solutions to Einstein’s field equations, known as Bianchi cosmologies, only a subset of which have ever been tested against data. For the first time, we consider all degrees of freedom in these solutions to conduct a general test of isotropy using cosmic microwave background temperature and polarization data from Planck. For the vector mode (associated with vorticity), we obtain a limit on the anisotropic expansion of (σV/H)0<4.7×10−11 (95% C.L.), which is an order of magnitude tighter than previous Planck results that used cosmic microwave background temperature only. We also place upper limits on other modes of anisotropic expansion, with the weakest limit arising from the regular tensor mode, (σT,reg/H)0<1.0×10−6 (95% C.L.). Including all degrees of freedom simultaneously for the first time, anisotropic expansion of the Universe is strongly disfavored, with odds of 121 000:1 against. "

It certainly sounds like a thorough test. I just wish I had a better understanding of how it was actually calculated.

So, I'll just say "Thank you" to Cat and consider my question answered.

 

[Rusty]

WOW!!!...What a tantalizing question!!!...I haven't read all of the responses, yet, however, I have an initial response that popped into my limited mind....

I did read "cat's" response, I think?...I agree with cats... What could we (the universe) be spinning around?...What would the "center" consist of...Or could it be that our universe spins around another universe?...If so, how do the hypothetical dimensions fit into the equation?...Would/could we be spinning around "those" dimensions...

Thank you for the question, unclear engineer!!!...I needed something "new" to quelch my boredum!!!...

 

[Catastrophe]

Unc

So, I'll just say "Thank you" to Cat and consider my question answered.

and your question was

So, it seems to me that spin should not be out of the question for the universe.

As long as we adhere to the original definition of Universe, then the Universe cannot spin - simply because there is nothing to judge that spin by.

And please remember that 'spin' has two different meanings - (1) as in the Earth spinning on its axis - and - (2) the Earth spinning around the Sun.

Cat

P.S. If you try to engage centrifugal force, then what is it pushing into?

 

[Unclear Engineer]

I initially asked the question because we see "spin" most everywhere, from galaxies orbiting each other down to subatomic particles. Black holes have "spin" that apparently drags "space" itself. If the universe was once far smaller than the size of an atom, maybe it initially had spin?

The other half of my logic has to do with unperceived forces that might arise in a spinning universe that we perceive as static. Could that explain expansion, for instance, particularly the incredibly rapid expansion theorized for the infant universe?

The discussion mostly revolved around how to even tell if there was net "spin" in the universe. Apparently, nobody here is good at solving General Relativity equations without "simplifying assumptions" (certainly not me).

However, Cat posted a link, repeated here: https://www.imperial.ac.uk/news/174...t spinning,turn form enormous galaxy clusters. which is based on a technical paper here: https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.117.131302 . That seems to say that the authors can show that there is no "spin" (nor preferred direction) in the universe. They used predictions of the cosmologic microwave background radiation based on General Relativity calculations and compared them to observations. From the into to the paper:

"A fundamental assumption in the standard model of cosmology is that the Universe is isotropic on large scales. Breaking this assumption leads to a set of solutions to Einstein’s field equations, known as Bianchi cosmologies, only a subset of which have ever been tested against data. For the first time, we consider all degrees of freedom in these solutions to conduct a general test of isotropy using cosmic microwave background temperature and polarization data from Planck."

So the answer to my question, at least so far, is that (1) yes, there is a way to perceive spin in the universe using the microwave background radiation, and (2) there is no apparent spin with that test.

However, there are still many things that we don't understand about what we see. So, I keep all of these things (that I know of) in the back of my mind as maybe being open for further thought as we find other things that we did not know before.

 

[Catastrophe]

Unc, have you seen "At the Edge of Time" by Dan Hooper.

He has an interesting thought experiment, where the Universe stays the same size, and everything in it gets smaller. This would sort out your centrifugal force issue. My interpretation would be that there is an inward force on the 'contents'.

Cat

 

[Helio]

Unc, have you seen "At the Edge of Time" by Dan Hooper.

He has an interesting thought experiment, where the Universe stays the same size, and everything in it gets smaller. This would sort out your centrifugal force issue. My interpretation would be that there is an inward force on the 'contents'.

The problem I have with Hooper's shrinking idea is that everything would have to shrink, not just space. How would we shrink the distance between two objects (and all objects), for instance, but not the mass and the force of gravity, which isn't linear, and produce the same exact results?

 

[Catastrophe]

Helio, I think he recognises the problem. He points out that everything would have to shrink even atoms, including the electron 'orbits', which I think he recognises as impossible. I do find the greatest difficulty in that I cannot 'copy' a quote to 'paste' here. It seems to be a function of Kindle? Anyone with similar experience?

He just suggests it, as I understand it, as an example to overcome the Universe expanding into what? question.

Cat

 

[Helio]

Helio, I think he recognises the problem. He points out that everything would have to shrink even atoms, including the electron 'orbits', which I think he recognises as impossible. I do find the greatest difficulty in that I cannot 'copy' a quote to 'paste' here. It seems to be a function of Kindle? Anyone with similar experience?

He just suggests it, as I understand it, as an example to overcome the Universe expanding into what? question.

But shrinking the orbits doesn't necessarily shrink the mass. IIRC, he failed to address the complications with his suggestion, and I think he neglected the mass issue.

If one shrinks the dimensions by, say, 1/2, including electron orbits, and shrinks the mass by 1/2, then the force of gravity would remain the same. But I would bet there are other laws of physics that would produce problems. If not, it would be interesting to see someone walk us through why it would work with things like quantum tunneling, or Rayleigh scattering (4th power law).

 

[Catastrophe]

Helio, I simply referred to Hooper's suggestion, which, as I understand it, relates to the question "into what does the Universe expand". He counters this by thinking what would happen if the Universe stayed the same 'size' and the contents shrank? I believe that he was well aware of the impossibility of such a thing. I will have to go find it, but I don't think that it was a "serious suggestion", and does not warrant pulling apart.

Cat

 

[Helio]

Helio, I simply referred to Hooper's suggestion, which, as I understand it, relates to the question "into what does the Universe expand". He counters this by thinking what would happen if the Universe stayed the same 'size' and the contents shrank? I believe that he was well aware of the impossibility of such a thing. I will have to go find it, but I don't think that it was a "serious suggestion", and does not warrant pulling apart.

Yes, of course, it was a "what if" scenario. Perhaps I failed to grasp what point he was making. Per GR, we can't possibly know what's outside the Universe, so I doubt he was addressing an alternative. I could re-read it, but I am curious what you think about his analogy first. [I'm not overly interested in it.]

 

[Unclear Engineer]

I just watched his presentation here:

View: https://www.youtube.com/watch?v=56Dc4ZPG0NQ


I don't see any real benefit to thinking about space being constant and the matter in it shrinking. The same issues just appear in a mirror fashion. However, the process of trying to think about how things would look as space expands or everything in it shrinks is useful. That is the same as the basis for several posts I have made here on Space.com. Thinking about how we might be misperceiving the actual causes of our observations may very well lead us to better understanding of how things really work.

Going to the other issues in his presentation in the link, above, I see that he is not so confident in the first second of the Big Bang as many profess to be. He does recognize that there are still many things that don't fit expectations of existing theories, and agrees that the theories may be incomplete and our current understandings wrong.

One of his statements about "dark energy" struck me as odd. He expressed the idea that dark energy is not stretched as space expands, so increasing the volume of the universe increases the amount of dark energy in the universe. Seems to me that is another "something from nothing" assumption, where energy is being created. So, he is postulating that the laws of physics are being broken continuously, right? And, if dark energy is the cause of the universe's expansion, and the expansion is leading to creation of more dark energy, this seems like a circular though process, anyway.

 

[Helio]

Going to the other issues in his presentation in the link, above, I see that he is not so confident in the first second of the Big Bang as many profess to be. He does recognize that there are still many things that don't fit expectations of existing theories, and agrees that the theories may be incomplete and our current understandings wrong.

I'm still reading the book, which I highly recommend, btw, but I haven't seen the video.

He argues that we have strong supporting evidence for BBT until we get closer than 1E-12 sec., since the LHC can study events that likely took place there. So he isn't saying BBT might be wrong, only that there are still things unanswered. The chase for DM, for instance, is certainly high on the mystery list. He does seem to favor the slow inflation model as opposed to Guth's sudden one, so the best explanations for the incredible level of isotropy, as well as, the incredible flatness of the universe may still be out there.

One of his statements about "dark energy" struck me as odd. He expressed the idea that dark energy is not stretched as space expands, so increasing the volume of the universe increases the amount of dark energy in the universe. Seems to me that is another "something from nothing" assumption, where energy is being created. So, he is postulating that the laws of physics are being broken continuously, right?

The only thing we know, at least are currently convinced of, is that the universe is accelerating. DE is merely a label to give us something to call it. There are dozens of "theories", though I'm not sure all can be tested.

The vacuum energy certainly seems like a great place to look. If DE has been around forever, but suppressed, somehow, but grows in strength with an expanding universe, then that might be one approach. Some have suggested that the expansion lowers the density and, thus, the gravitational strength, which would give DE some overpowering strength (assuming it doesn't decrease in density itself). [Added: Lemaitre, IIRC, actually showed acceleration in his model, though perhaps not in his 1927 paper.]

There is the other little detail in that the discrepancy between quantum physics and GR is 1E120! [There's a wrinkle! ]

 

[Catastrophe]

Does our universe have "spin"

Did I miss something about the universe spinning?

Cat

 

[Unclear Engineer]

The only thing we know, at least are currently convinced of, is that the universe is accelerating.

I am not convinced of that.

I see 3 methods for measuring the distance to compare to the red shift, each for a different range of distance, but with some overlap. All 3 use a linear model, so there is a straight line on each graph. The nearest distance graph has a line that indicates a faster expansion rate than the other 2 graphs. The analysts argue that the uncertainty in their measurements have now been made small enough that the line in the nearest graph is clearly showing a higher expansion rate than in the other 2, more distant graphs.

First, the evaluations of uncertainty are almost always underestimates. Besides a wishful thinking bias, there are usually things that we just don't realize are complicating the data in most of our endeavors.

But, more importantly, what it would take to convince me that there is a real effect in the data would be a combination of the data into one graph that shows some sort of non-linear curve in the distance vs redshift relationship. The "coincidence" that there is a sharp change in expansion rate that just happens to occur where we shift distance measuring techniques (from our non-special point of observation in the universe) doesn't seem likely to be real.

So, does anybody posting here have a unified methods graph of redshift vs distance for the whole distance range? And, has anybody tried to fit a non-linear curve to that data?

 

[Helio]

There have been many papers on an accelerating universe. This seems to be a decent Overview.

The two 1995 teams that tried to nail-down the expansion were both stunned with their independent determination for acceleration.

Interestingly, the Harvard team barely beat the Berkeley team because they more wisely chose to use multiple filters to produce a stronger sigma, though they had fewer data points. [Oddly, I see more credit going to Berkeley.]

iPhone

 

[Catastrophe]

Come on guys . . . . . . This is the thread:

Does our universe have "spin"

Spin must be relative to some fixed external marker. What fixed external marker is there "outside" all that exists (i.e., universe)?

Cat

 

[billslugg]

Yes, practically speaking, if the universe were spinning, it would be at such a low RPM that we could not detect it unless we had an outside reference, which we don't have.
Spin, if it is fast enough, should be detectable without any outside reference. When you are on a spinning carnival ride with your eyes closed there is no doubt you are spinning.
In a spinning universe, all ballistic trajectories would be curved I am pretty sure. Perhaps that might be a method of detection.

 

[Unclear Engineer]

Cat,

Obviously, this thread has drifted.

I thought the link you posted in reply #24 provided the best available answer to my original question, and said so in reply #27. For me, that would have closed the thread.

But, you as well as others have introduced other issues since then, and I have responded to some of those issue, myself.

Perhaps we should start other threads on the other subjects, or maybe attach them to some existing threads. But, to do so will require that we somehow transfer the material that initiated the new subjects from this thread to the new thread(s).

To try to close out the "spin" subject, it seems that the study you provided a link to in reply #24 shows that there is no spin to the universe to a pretty good level of confidence.

So, that makes the difference you and I have about whether "spin" as a property of the universe requires an external (to the universe) point of reference somewhat irrelevant.

To restate what I think the 2 positions are: you seem to be saying that, without an external reference to compare it to, spin cannot exist , because there can be nothing "external" to the universe because the universe includes everything by definition.

My position is that spin is an intrinsic feature that can exist without any need for an external reference. A spinning frame of reference has different internal dynamics compared to an inertial frame of reference. My question was whether we would be able to recognize spin if it exists, or would we see the effects of the related accelerations and call them something else (maybe "dark energy"") in a manner similar to the way we call the tendency of the winds on our rotating Earth to turn from a "straight" (but actually curved) path the "Coriolis Force".

The paper you provided in your link seems to indicate that the relativity equations can be solved for cases with spin in the universe, and the predictions from those solutions for how the cosmological background radiation should look can be compared to observations to see if it looks like what spin would cause it to look like.

So, I think the paper in your link bears out my understanding of "spin" for the universe, but also supports your belief that none exists.

So, the only outstanding disagreement between our 2 positions is whether "spin" in the universe is excluded from possibility by the definition of "universe" or is theoretically possible. even if not found to occur.

 

[Stellarwest]

Just from perspective galaxies rotate around black holes so in order for the universe to rotate or spin it would take a massive black hole that I'm sure we would be aware of I feel.

 

[Unclear Engineer]

Continuing with the drift:

Helio, I did look through some of the papers in the link you provided in reply #41, and did not find the simple graph combining the 3 methods of determining redshift vs distance over the 3 distance ranges of the different techniques. So, also no attempt to fit a non-linear curve to the combined data sets. If that is in there somewhere, please point it out.

 

[Helio]

Continuing with the drift:

Helio, I did look through some of the papers in the link you provided in reply #41, and did not find the simple graph combining the 3 methods of determining redshift vs distance over the 3 distance ranges of the different techniques. So, also no attempt to fit a non-linear curve to the combined data sets. If that is in there somewhere, please point it out.

Perhaps this will work better: Here.

 

[Catastrophe]

Please excuse my confidence, if mistaken, but it seems to me rather strange to argue that the Universe can spin if there is nothing against which to confirm any such spin.

If centrifugal force is to be proposed, then I would ask a good scientist to measure it and please report back.

And if it still be questioned as being too small to measure, then my reply would be "What sort of science relies on something being there, even if it cannot be identified or measured? Metaphysics?

Cat

 

[Unclear Engineer]

Perhaps this will work better: Here.

Helio, Still not what I am looking for, because it is just one of the 3 distance measuring techniques. Yes, it does show a bit of "acceleration", but only if the assumptions about apparent brightness are all true.

I would still like to see a curve that shows the data from all 3 distance measurement techniques on the same graph.

 

[Helio]

Helio, Still not what I am looking for, because it is just one of the 3 distance measuring techniques. Yes, it does show a bit of "acceleration", but only if the assumptions about apparent brightness are all true.

Brightness is, of course, about all astronomers have to work with. But, for expansion itself, the dilation in brightness over time for Type 1A is very important. The farther SN demonstrate they are moving away from us faster when compared to the closer SN.

I bet you will find what you want if you search in arxiv.org (Cornell).