The block universe is essentially conceiving of the vector space (x,y,z,t) as a space-time manifold - as if when all components were free to vary along their ranges, we have a continuous set of snapshots of all events. This isn't implied, what is implied is that for a given equation of relativistic motion there is a space-time 'block' corresponding to its trajectory over space through time. It would be odd to consider space time an invariant block when the things within it can distort all of its motions with their particular properties.
I thought you would've quite liked this, special relativity produces a multiplicity of blocks and the Lorentz transform renders the blocks reconcilable. Which is to say, with a more ontological framing, the unfolding of the universe is relative to the trajectories of its localising elements - the differentials of movements - but the category of relativistic motion nevertheless has a clearly demarcated set of potentials. — fdrake
I know I briefly addressed this exact passage in my post prior, but on further reflection, there's more to be said with respect to the question of time, which was what this discussion was motivated by. While I still do like this, I think this actually speaks quite nicely to Bergson's point here re: what I referred to as a desubstantialization of time: to the degree that every space-time block is relative to the trajectory of it's localising elements, what is missing or simply untheorized is precisely the
passage from one trajectory to another. In other words what is missing, or rather, what is simply assumed is
time itself. Time is 'given': given
this space-time trajectory,
that is the corresponding space-time block. But the passage of time itself is precisely what takes place 'before' (logically speaking) STR 'kicks in', as it were.
It's important to emphasise that this is not a
'fault' of STR. It speaks simply to its
scope, and what kind of implications can be drawn from it. When I said that STR does not provide a substantial theory of time, this is what I was getting at. Time itself takes place 'behind it's back', as it were, and STR explores - in a totally legitimate way - what can be predicted
given that fact of time's passage. But this passage itself does not fall within the scope of STR. One cannot draw a temporal ontology from it without losing the very thing it ought to account for: time.
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The article linked by Rich above is actually quite fascinating to read in this regard (
https://phys.org/news/2011-04-scientists-spacetime-dimension.html): It begins quite well by noting that "it’s more correct to imagine spacetime as four dimensions of space", and that "Minkowski space is not 3D + T, it is 4D". But from there, instead of concluding that, as a result, STR is simply
silent on the question of time (i.e. it says
nothing about it either way - which is
the whole point of their own reconceptualisation!!), it infers instead that "the universe is “timeless” (!!!). It's basically a classic case of looking for the lost key under the streetlamp and, not finding it there, concluding that there was never any key to begin with. But what it 'wrong' here is not the theory - which in fact, the scientists have exactly right (insofar as they correctly recognise, perhaps more acutely than any before, that it's four dimensions of
space at play) - but the implications drawn from it. Excellent science, abysmal philosophy.