The book is pretty much what one might expect - photos of galaxies, with their names and numbers, and commentary on them. It’s the latter that is disappointing. For such significant structures, there seems to be limited theoretical explanations that describe what is being seen.
When viewing these pictures, it’s helpful to remind oneself that these are not stars that we see, but billions of stars. Galaxies are round, which presumably involves the gravitational gathering of energy into matter-filled bodies. As gravitational structures, shouldn’t they illustrate in some way Einstein's theory that they, like stars, warp the universe’s “fabric” and geometrically cause the inflow of energy (gas, dust) into the center? But nowhere in this book (there were many pages missing) is that notion referenced. (1) Neither is there an explanation of why spiral arms exist at all. Might these arms be the inflow toward a gravitational center, getting tighter and tighter per Newton’s inverse square law? Ferris does note that intergalactic collisions have a lot to do with arm formation in the sense that there’s either an exchange of gas and dust, or the larger body pulls such from the smaller body and that the pulling has a “wafting” effect - a pulling from one galaxy toward another (i.e. the arms are outward spirals for the smaller galaxy and a pulling inward toward the larger galaxy). This hints of Einstein’s theory, but what about non-galactic collisions? Wouldn’t this gathering of space material into galactic arms occur generally - like a sweeping up function?
And then there’s this issue of the so-called “depressions” in spacetime’s “fabric” - as conveyed by commonly depicted diagrams of Einstein’s theory - so that movement flows downward toward a massive gravitational center. Yet, the pictures in this book are those of galactic disks with bulges at the center that are something other than vertical depressions. Depressions in spacetime don't seem to capture what is involved. As all mass-energy flows toward a gravitational center, the flow would be from all directions not just from the top town, and this (versus a depression) is what the galactic bulges represent.
Regarding the second major feature of galaxies (massive roundness, including the spiral arms, being the first), the inward flow inward of mass-energy (2) is subject to rotation (hence, the galactic spirals). Is rotation the geometric flowing inward, toward the gravitational center, or, more generally, is the rotation inward, outward or both? In addition, if a pulling inward, horizontally, toward the center is one manifestation of gravitational “force” (3) forming the bulge at the center, is there also a simultaneous vertical pulling together of mass-energy, thereby creating a disk along the galactic plane (the galactic equator) where the gravity of a rotating structure is the strongest? Then, again, as the arms move toward the center, they begin to merge, suggesting the stronger effects from gravity per the inverse square law. And finally, doesn’t inertia, gravity’s stepchild, play a fundamental role in all this galactic movement? The movement toward the gravitational center via “attraction” (i.e. movement following geometric paths toward the center) is countered by the inertial force of the “pulled” body that wants to continue its straight-line motion: The equilibrium point between gravitational pull and inertial resistance (pushing away) is somewhat close to 45 degrees (pure orbits) or variable (elliptical orbits), that creates the orbiting effect around a rotating body.
A third area not covered well by this book is on the possible sequences to the main types of galaxies (elliptical, spiral, barred, irregular). Ferris discusses classification without going into why some might end up in the one category versus the other. The one exception is his discussion of irregular galaxies that seem to be formed by chaotic forces that take a few million years to sort out. But maybe Einstein’s theory can help out: It’s almost like the sequence - this combo packaging of inertial motion (a pushing away) and gravitational “forces” (a pulling inward) is first manifested in the “ordering” of chaotic mass-energy for irregular galaxies that sort themselves into spiral galaxies (with two main arms - not an insignificant observation as gravitational pull inward would logically consolidate from two directions, hence poles), that further pull inward to form the barred galaxies (again, the barred future being a pulling in or a spitting out feature, or some of both at each pole?) that are bulges without spiral arms or barred features, and lastly, elliptical structures where gravity concentration wins out over inertial countering movement. (4)
As a last point, Ferris references galaxies, local galaxies, galactic clusters, and superclusters and super-super clusters, all held together by gravity. Extending that concept, would this not mean that the universe has an overall gravitational structure that has its own barycenter, meaning that straight-line inertial motion continues around a spherical universe and back to its putative beginning, thereby combining the concepts of expansion, steady state(a brief transition point between expansion and contraction), and contraction ( a continuing around, not a reversing of direction), regarding the history and future of the universe? Extend this logic further and one bumps into the singularity issue and its incompatible pressures that result in a (renewed) big bang explosion. (5)
While I can't say whether any of this accurately describes what is being seen, what’s exciting is the possibility of looking beyond photos and seeing these galactic structures as Einstein’s theory of spacetime in action (“real” time).
1. Ferris does describe the universe’s flat-open-closed scenarios, but that doesn’t shed much light on what is going on with galactic structures.
2. Einstein equates matter and energy, with matter being concentrated energy and “energy” being energy per se (liberated mass), but the post-Einstein references write of matter as if they are separate from each other. The hyphenated mass-energy (Einstein’s terminology) might be the preferable expression as it escapes the matter’s separation from the energy problem, with energy and its amount (mass) being the umbrella term.
3. Another question: why does rotation go in one direction and not the other or, alternatively, why does one body rotate in one direction and another body rotates another direction?
4. There does seem to be (though not in Ferris) observational evidence for a different sequencing with galactic formation.
5. Why would black holes not be singularities that also explode?