Bradford Skow reviewed our book for the Notre Dame Philosophical Reviews and therein provided an example of what happens when the reader is unwilling or unable to suspend their dynamical bias while reading the book. We warn the reader in Chapter 1:
This [dynamical bias] is a very hard bias to overcome; ironically even the many philosophers and physicists who claim to believe in the block universe ontology still adopt the ant’s-eye view and assume that fundamental explanation is [dynamical]. Therefore, we must ask that you make every effort to suspend this dynamical bias as you read the book.
But, he writes:
It really is necessary to register how wild this idea is. I myself, at least, think that the first claim [dynamical explanation] is true but that the second [adynamical explanation] is certainly false.
This leads him to dismiss out-of-hand our 4D-constraint-based explanation:
Of course, if you explain the initial state of the universe by citing a later state, you probably shouldn’t explain that later state by citing the initial state; it can't be both that A because B and B because A. If physicists follow SSM's advice, can they then explain every state of the universe? That is, for each region of spacetime, can they explain why that region of spacetime is in the state it is in, without ever asserting both "A because B" and "B because A"? If this cannot be done then there is at least one region of spacetime with the property that that region's being in such-and-such a state remains unexplained.
If you understand and are willing to consider the thesis presented in the book, then you can see immediately by the reviewer’s statement that his questions miss the point entirely. Einstein’s equations can be viewed as a self-consistency constraint as explained in Chapter 3. First, we explain what the metric is and how the left-hand side of Einstein’s equations (the Einstein tensor) is a very complex function of the spacetime metric. Then on p. 105:
The SET [right-hand side of Einstein’s equations] describes the matter–energy-momentum distribution in spacetime, so in order to provide the elements of the SET you have to know spatial and temporal distances for momentum, force, and energy. Of course, knowing spatial and temporal distances means you already know the metric. Therefore, you should view Einstein’s equations as providing a self-consistency criterion or a “global constraint” between what you mean by spatial and temporal measurements and what you mean by momentum, force, and energy. Any combination of the metric and SET that solves Einstein’s equations on the spacetime manifold M constitutes a solution of GR.
With this understanding it is obvious that indeed the GR solution at any point on M depends self-consistently on the solution at all other points on M, just like a crossword puzzle. So, yes, “A because B” and “B because A” per the adynamical global constraint (AGC, Einstein’s equations in this case) is exactly what adynamical explanation means. We answer his questions on p. 110:
Ultimately, a solution—a self-consistent metric and SET on the entirety of M—depends on two things: the adynamical global constraint (Einstein’s equations) and information in accord with observations for any location on M. In this block universe perspective, one could still ask regarding spacetime, “why do we observe what we observe rather than something else?” This question replaces its counterpart in the mechanical universe, “why these initial conditions rather than some other?” In [adynamical explanation], conditions at any location on M are said to be consistent with conditions elsewhere on M. It is this spatiotemporal contextual consistency per the adynamical global constraint that ultimately explains the conditions at any particular point on M in relation to all other points on M. There is no explanatory priority of one location over another in [adynamical explanation]. Accordingly, the only mystery would be the existence of M as a whole which is beyond empirical investigation and therefore beyond the purview of physics in this way of thinking. Thus, most would say that the principle of sufficient reason (PSR) cannot be satisfied on cosmological scales by empirical science in our “spatiotemporal ontological contextuality.”
And again on pp. 114-115:
Again, one could ask, “why is there an M at all?” And, certainly one could engage in speculation concerning M with metric-SET configurations and/or adynamical global constraints that do not represent our experience. Such counterfactual speculation wouldn’t lend itself to empiricism, by definition, but we wouldn’t condemn it as an “unworthy academic exercise” either. The point is that while we speak of doing physics from a God’s-eye view, given our contextuality and relationalism, there is no literal “view from nowhere” [Nagel, 1986] from which to ask “why does the entire relational block universe exist?” Such questions presuppose the dynamical perspective and the only answer one can give to such questions in our view will be in terms of counterfactual adynamical global constraints and alternative metric-SET configurations, that is, answers residing outside the purview of empirical science.
Again, these mysteries arise because the time-evolved bias of our ant’s-eye view demands dynamical explanation and a dynamical story about the universe traced backward in time leads ultimately to conditions in the very early universe. Again, per Wilczek, “The account it gives—things are what they are because they were what they were—raises the question, Why were things that way and not any other?” [Wilczek, 2016, p. 37]. The key to avoiding this explanatory problem is to relegate dynamical explanation based on time-evolved stories to secondary (non-fundamental) status and accept that the more general block universe explanation based on a spatiotemporally global constraint is truly fundamental. This is adynamical explanation per the Lagrangian Schema Universe. In this more general adynamical explanation, Einstein’s equations are understood as a global constraint, that is, a self-consistency criterion for the metric and SET on the spacetime manifold M. While time-evolved stories can certainly be told in GR solutions, there well may be events in a GR solution that resist such dynamical explanation, for example, the origin of the universe or the question “why were things that way and not any other?” In those cases, we just have to accept that reality is best understood adynamically in spatiotemporally holistic fashion.
So, you cannot be "Skowed" if you want to appreciate the explanatory power of the "all-at-once" view and rise to Wilczek's challenge. You must set aside your dynamical bias as you read the book!