Hi Jonathan and Edwin:
The local reconciliation of temporal passage that's supposed to come from denying a metrical relation between events that exist outside one's past light cone is Howard Stein's thing. However, as Craig Callender pointed out in "Shedding Light on Time", by positing that "at least one event in the universe shares its present with another event's present", which he considers to be "the thinnest requirement one could put on becoming", "Stein's 'possibility' theorem [is transformed] into a 'no go' theorem for objective becoming in a Minkowski spacetime". Basically, what this means is that if we can say that *even just one event* exists at some metrical distance outside the light cone of another event---like, for instance, the emission of a photon by the Sun anytime in the past or future eight minutes---Stein's theorem tells us that the common way of describing what is "present" in relativity theory demands a block universe.
I believe in the existence of Physical Reality, despite the fact that I can't know what simultaneity-relation describes the sapcelike surface that exists at any instant as I'm looking at my watch, because every experience I've ever had in my life tells me it's there. Therefore, although we can't scientifically prove or disprove its existence, I think a pure verificationist way of looking at things is the wrong approach. It doesn't lead to any clear understanding of things, but only allows some people the opportunity to wave their hands or shrug their shoulders.
Therefore, given Stein's theorem, and the fact that I believe the Sun exists now---as in, I believe there's a well-defined spacelike metrical distance between the Sun and me now, which has a different length (and, e.g., isn't synchronous) in different coordinate frames---even though I won't see what it looks like now for another eight minutes---I completely agree with Roger Penrose's remark, when demonstrating his own version of the Rietdijk-Putnam argument in The Emperor's New Mind, where he notes that whether one uses observers' light cones or their simultaneous spaces makes no difference at all to the conclusions. ("Some relativity 'purists' might prefer to use the observers' light cones, rather than their simultaneous spaces. However, this makes no difference at all to the conclusions.")
As to denying the relevance of coordinating distant spacelike events with a metric, that is not something that should be done lightly, and I think it just leads down a rabbit hole. All of science is based on the use of a metric---rather than a more general abstract topological space---to describe "distances" between two events, and there's a mountain of scientific evidence to support the fact that, regardless of which coordinate system is used, there is a Lorentzian metrical relation amongst all space-time events. This is the very reason why proper times are measured differently by observers in relative motion, and there is indeed a well-defined metrical relation between them according to relativity theory. Therefore, in relation to my above remarks, I think it's just wrong to argue that this metrical relation should somehow only crystallise when events enter one's past light cone, which is what I can only take your comments to mean.
I've already noted elsewhere on this blog a very relevant observation that Tom Ray made in his essay: 'One recalls that prior to Descartes, all geometry was done with compass and straightedge---all "here" and no "there." Only with the development of analytical geometry were we able to identify relations between numerically distant points and a local coordinate system.' I don't understand why you would *want* to reject this. I agree that it seems to be hard to reconcile it with relativity without concluding that there has to be a block universe; but if you'd rather accept instead that it does work---and I'm certain that it does---I think you'd see that the interpretation of the emergence of relativistic space-time that I've described in my essay really works. The key assumption is that the metrical relation amongst events in space-time has to be Minkowskian, just as it is in the block universe theory.
The linguistic thing is essential to forming a clear understanding of the problem, and how the theory works; and there are in fact important distinctions that need to be made between the meanings of *two* words in order to understand how special relativity can be reconciled with a flowing present. First and foremost is the copular verb: as Steven Savitt argues (see the top paper) it's really through a carelessness with the word "is" that McTaggart was able to show, even from a Newtonian perspective, that the past, present, and future are all equally real. According to presentism (which McTaggart tried to argue against), the past and the future do not "exist" in the same sense as the present, which is all that's supposed to be real. Instead, the past and future exist, according to the presentist viewpoint, *ideally*---i.e., brains, photons, computers, books, etc., existing in the present, carry, or form ideas about what was in the past or will be in the future. This is an extremely important distinction to make, because confusion does arise when one thinks of the real present as somehow flowing through the space-time continuum of events, with any particular event in the future existing as such until it eventually becomes present, then past---even if we're thinking of this sense of "existence" as something abstract---and it's only amidst such confusion that arguments like McTaggart's (or, e.g., those of Huw Price) prevail.
But when one thinks of the present as enduring, with the ideal past emerging in its wake, as an unreal thing about which records exist in the present, and the ideal future as something that's anticipated in the present, there's no reason to think of McTaggart's argument as anything more than a misuse of semantics. As I noted before, it's also this way of thinking of all events throughout (space-)time as existing in some way that can be travelled to, that leads people to time travel paradoxes.
This presentist thinking makes perfect sense from a Newtonian viewpoint. But relativity throws in another monkey wrench, because what is meant by "time" is---at least in one sense---not universal. Two events that occur at the same "time" according to one observer will happen at different "times" for another observer, and clocks will tick at different rates. For such reasons, it's difficult to see how it could be possible to reconcile a view that everything only exists "now" with relativity theory. The way to do this, I've argued, is to first make note of the distinction between space-time, as a four-dimensional *ideality*, and an enduring three-dimensional *reality*---a flowing Heraclitean present, with an absolute time defining an absolute simultaneity-relation, and associated sets of events that *truly* occur simultaneously, in a Newtonian sense. These events obvously then have to be said to occur at the same "time"; however, as described in different relativistic space-time coordinate systems, viz. those used by observers with non-zero absolute motion, the events that occur at the same "time", in the pre-defined sense of simultaneity, will not occur at constant values of the time-coordinate.
Therefore, along with the distinction that I think needs to be made between the "existence" of "ideal" past and future and a "real" present, I think it's also very important to make a distinction between events described as "synchronous" in a given frame occurring at the same "time", and events that truly occur "simultaneously", at the same cosmic "time".
Best,
Daryl
