[...] My argument is that time itself is non-existent and is only a simultaneous side-effect and emergent property of an unfolding reality. ("Explicate Order", Bohm) and (CDT, Causal Dynamical Triangulation, Loll et al) [...] And I am still waiting for an "objective" argument that does not involve "observers" that subjectively experience individual slices of time relative to their frame of observation.
But otherwise, I personally don't see the point in entertaining a global now to begin with unless one does indeed adhere to your "unfolding reality" conception, or one is a basic presentist who believes the universe is constantly replacing itself with a different state (they don't co-exist), or one is a buff of Julian Barbour's work[1], etc. That should probably include
GBU believers, also, except that option seems to endanger its existing past as being superfluous, should its advocates contend that only the organisms abiding in the edge of the additive process are conscious (in terms of experiencing change and everything else). IOW, it thereby might as well be presentism, or slide back into it.
This sets aside the solipsistic-like impression of most individuals (parties of this thread exempted from the possibility of facilitating such) apparently selecting their own brain-dependent, subjective and varying mental experience of "this moment" as their "objective or mind-independent Now". Which is a milliseconds in duration elephant (and again, irregular in its measurement by scientists who examine such psychological features).
A legit, objective now would have to accommodate changes at the subatomic level, to the extent of being a
yoctosecond in duration, if not a
Planck-time unit. (And physicists in the past usually dissed the idea of reifying the latter, deeming it simply being the limit of meaningful measurement for disciplinary work and theories.)
Returning to that "giant" duration of the brain's mental representation of a Now or its cognitive registration of change... The issue becomes all the more inconsistent when considering that the experience obviously can't "fit" into the infinitesimal duration of a yoctosecond or Planck-time unit. It would have to extend over or through multiple co-existing [objective] Nows or a chunk-sequence of "faster" electrochemical changes in the applicable neural structures, thus nuking the very conception of
presentism, which only accepts a single, ephemeral state of the universe existing (which it labels "present", "now", etc).
The above said, however, if someone preferentially wants to be a presentist, Barbour-ite, "unfolding reality advocate", or alternatively engage in the oddity of believing "something" in the rival
eternalism conception is objectively "flowing" through the block-universe in a distinctly incremental, Now-istic way... Then all the power to them in their crusader cause. Presentism, at least, is after all the norm/view of the bulk population (though it's probably an implicit belief for most people, rather than an explicit or verbally expressed one).
- - - footnote - - -
[1]
Even Barbour has all the possible Nows or "configurations states of the universe" in his conception co-existing in an onto-mathematical landscape he calls "Platonia". They just compete in some quantum statistical fashion for which one is most likely to be the next Now that is concretely realized.
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