I suggest the the short answer to this cosmological question is quite simple: galaxies spiral because the whole early expanding universe spiralled outwards, and that the results of research findings indicating the nature of the whole early universe provides one piece of evidence that this causal relationship applies. Although, of course, if only because it conflicts both with theories of how galaxies retain their spiral structure over time and with the current theory of cosmological inflation, for this causal relationship to be taken seriously as a scientific theory there would need to be a much longer answer with more supporting evidence, some of which will be provided here. Thus, especially, there is the question of the acceleration in the expansion of the universe and why the rate of this acceleration should be related to the galactic orbital acceleration of stars. Then also, this close match in acceleration rates can be said to raise problems with theories of both dark matter and dark energy .
But ultimately, I propose, the full solution to all these and other problems of the universe on the large scale requires the development of a whole new cosmological theory. This would be an account where sufficient evidence is examined together so as to justify and describe enough clearly definable and repesentable details of a nonlocally acting cause with effects upon matter and energy in addition to those of the known forces. Such effects would need to include those that have been uniquely described of the behaviour of quantum objects that include electrons and photons.
So in such a new theoretical development questions would need to be asked like: Could the problem of the origin and retention of the spiral form of galaxies be in some way related to quantum mechanical problems of atoms of molecules, and in relation to the wave property of electrons and photons in particular? And so, given that there is already a detailed theory of the evolution of matter as subatomic particles and then atoms in the early universe, could there be such a theory of the origin and nature of the quantum wave property?
And if cosmological inflation theory is incorrect, could there be a nonlocal theory for the overall (approximate) uniformity of the universe and the evolution of structure on the galactic and larger scale?
Hence the quantum evidence can be considered to indicate that the quantum wave is somehow a real but nonlocal causal property that, for electrons as atomic and molecular components, allows them to resist the powerful attraction from the atomic nucleus. While the photon's wave allows it to possess wavelengths of up to 100,000 kilometres for the longest radio waves. One may then ask whether such a nonlocally acting cause could produce significant and measurable effects in addition to those of gravity, and especially on the galactic and larger scales. Also, one can consider whether what caused the universe as a whole to expand and accelerate in its expansion could be the same as what causes electrons to remain in their atomic orbitals and resist the powerful attraction towards the nucleus of the electrmagnetic or electrostatic force.
So this image was produced by data from the Wilkinson Microwave Anisotropy Probe or WMAP. This is a spacecraft with instruments that have measured the invisible microwave background radiation (CMB) that is generally regarded as what remains of the energy that was produced just as the universe became atomic for the first time, and when the cosmos was around 300,000 years old.
The WMAP image represents a panoramic view of the variation in the energy of the CMB, and thus in the energy of the early universe, with the different colours here picturing the slight variations in the density of the microwaves, and therefore the density variations or anistropies in the distribution of matter. So that the red spots repesent the most energy dense areas, the yellow the less dense parts and the green still less dense.
The WMAP findings have posed a problem with the inflation theory of the very early universe that, while predicting the small scale density variations, it also pedicted that the density should not vary when averaged out overall.
Whereas what was actually measured was a preferred overall direction to the CMB or what two cosmologists have called an "axis of evil" , and so that this can be seen as more red, yellow and green overall on the right hand side than to the left of the WMAP image. Although I've yet to find anyone publicly suggesting that the preferred direction could be due to a spiralling early universe. But what about this?The evidence that the expansion of the universe as a whole and galaxy rotation are related is more subtle. But this relationship has been described in quite simple mathematical terms of a close match of acceleration rates by the theoretical physicist Lee Smolin in chapter 13 of his book The Trouble with Physics. Various aspects of Smolin's book have been both highly praised and severely criticised, but this is the only source I've found that describes in clear detail how the orbital acceleration of stars in galaxies can be related to the acceleration in the exansion of the observable universe as a whole. So that I have yet to find any critique of Smolin's reasoning regarding this remarkable galaxy/universe relationship.
So while Smolin does not see any connection between the WMAP results and galaxies, he does point out problems that inflation theory could have with these results, including the preferred overall direction in the energy density. He also suggests that the observaton could be a statistical anomaly but notes that the estimation of the chances of such a glitch given in the 'Axis of Evil' paper was about a thousand to one.
[to be continued]