"A fundamental assumption in the standard model of cosmology is that the Universe is isotropic on large scales. They used predictions of the cosmologic microwave background radiation based on General Relativity calculations and compared them to observations. That seems to say that the authors can show that there is no "spin" (nor preferred direction) in the universe. which is based on a technical paper here. However, Cat posted a link, repeated here: universe is not spinning,turn form enormous galaxy clusters. Apparently, nobody here is good at solving General Relativity equations without "simplifying assumptions" (certainly not me).
#Spin spacie how to
The discussion mostly revolved around how to even tell if there was net "spin" in the universe. Could that explain expansion, for instance, particularly the incredibly rapid expansion theorized for the infant universe? The other half of my logic has to do with unperceived forces that might arise in a spinning universe that we perceive as static. If the universe was once far smaller than the size of an atom, maybe it initially had spin? Black holes have "spin" that apparently drags "space" itself. I initially asked the question because we see "spin" most everywhere, from galaxies orbiting each other down to subatomic particles. So, I'll just say "Thank you" to Cat and consider my question answered.
I just wish I had a better understanding of how it was actually calculated. It certainly sounds like a thorough test. 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. 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.). 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. 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. 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. The abstract for the paper referenced by the article gives a little more detail: The question is not being ignored, and the tests to date indicate no discernable spin.
But, I think this does answer my question to the extent that we can answer it now. 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.
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