On Tue, Dec 18, 2018 at 11:14 PM Bruce Kellett <[email protected]> wrote:
> From: Jason Resch <[email protected]> > > On Tue, Dec 18, 2018 at 7:27 PM Bruce Kellett <[email protected]> > wrote: > >> On Wed, Dec 19, 2018 at 12:19 PM Jason Resch <[email protected]> >> wrote: >> >>> On Tue, Dec 18, 2018 at 6:45 PM Bruce Kellett <[email protected]> >>> wrote: >>> >>>> On Wed, Dec 19, 2018 at 11:27 AM Jason Resch <[email protected]> >>>> wrote: >>>> >>>>> On Tue, Dec 18, 2018 at 6:05 PM Bruce Kellett <[email protected]> >>>>> wrote: >>>>> >>>>>> On Wed, Dec 19, 2018 at 11:02 AM Jason Resch <[email protected]> >>>>>> wrote: >>>>>> >>>>>>> On Tue, Dec 18, 2018 at 3:23 PM John Clark <[email protected]> >>>>>>> wrote: >>>>>>> >>>>>>>> >>>>>>>> Arithmetical computations don't change so there can't be a >>>>>>>> correspondence between them and the evolution of spacetime or with >>>>>>>> anything else that can change. >>>>>>>> >>>>>>> >>>>>>> "y = 2x+1" defines the arithmetical relation of "oddness". >>>>>>> >>>>>>> Solutions to this equation yield (compute) for *y* all possible odd >>>>>>> numbers. *y* changes with respect to increasing values of *x*, >>>>>>> just as John Clark's brain changes with respect to increasing values of >>>>>>> *t*. >>>>>>> >>>>>> >>>>>> How does 'x' change? >>>>>> >>>>> >>>>> With respect to y, and vice versa (like your brain state and your >>>>> location in spacetime). >>>>> >>>> >>>> Poor analogy. Change in the physical world is governed by dynamics, >>>> described by equations with a veritable 't', called time. Time is probably >>>> only a local phenomenon, but I do not see any 'time' variable in >>>> arithmetic. >>>> >>> >>> It depends on the equation. >>> >> >> What equation? There are no dynamics in arithmetic. >> > > There are computations. > > But no dynamics. > I'm not sure what this means. Not dynamic in what sense? > > The analogy with the block universe idea is useless, because the block >>>> universe idea is only a picture, not a reality. Special relativity merely >>>> abolishes any notion of Newtonian absolute time, it does not prove that all >>>> instants of time are equally and simultaneously existent. The whole notion >>>> of simultaneity is abolished in relativity. Minkowski's block universe was >>>> a response to this, but not a very good picture in the final analysis, >>>> because it completely fails to capture the local dynamical aspect of the >>>> time variable. >>>> >>> >>> Did you read https://core.ac.uk/download/pdf/11921131.pdf ? >>> >> >> No. Why should I? >> > > Because you believe relativity cannot be used to justify the block > universe concept. > > > I do not have the time or inclination to rebut every argument that is > presented in arbitrary papers. But if you abandon the idea of > 'simultaneity' as used in this paper, the objections to the idea of "the > present" as a ourely local concept collapse. > > Then you have already abandoned the idea of a 3-dimensional space evolving in time. How does this not leave "block time" as the only view that preserves an objective global spacetime? Why give up an objective realist view that captures all of spacetime when you do't have to? This reminds me quite a bit of the break down of the naive conception of personal identity. The normal view is each person's experiences are bounded by either psychological or biological continuity. Thought experiments such as duplicating or permuting minds show neither of these can work. The only consistent choices that remain are: 1. "universalism" -- all experiences belong to one universal experiencer 2. "no-self" -- there are only single individual thought moments The thought experiments of relativity, such as the Rietdijk-Putnam experiment, lead to a similar break down. You either reduce what exists "presently" to a collection of independent events (points) in space time, or you expand it to include all of space time. But in both cases, you are saying what exists in the present is the same (all points in space time vs. all of space time). I'm not sure you there is really a conceptual difference. > What is your interpretation of the >>> https://en.wikipedia.org/wiki/Rietdijk%E2%80%93Putnam_argument ? >>> >> >> The "present" is a local concept which cannot be extended to global >> hyperplanes. >> > > Which would means there is no such thing as a present point in time. > > > No, the idea has no such implication. > > > Remember, the only sensible definition of "time" is an operational >> definition -- "time is what is measured on a clock". This is a purely local >> concept. >> > > So then you have reduced the present to a point in spacetime, a single > event. > > > Strictly speaking, yes. But for practical purposes, the spatial extent of > the "present" can be defined as that region over which the travel time of a > light signal is negligible compared to the characteristic time scale of the > processes of interest. > So strictly speaking, every event in spacetime exists in its own present. Isn't this the same as saying everything exists in the present? i.e. everything in space-time exists? If not, then what experiment could be done to determine between the block-time view of space time and this theory of every event in space-time existing in its own present? It isn't clear to me how those concepts even differ philosophically speaking. > > Do you agree in principal, that human experience of a dynamically evolving >>> universe cannot be used to decide between block time and presentism? >>> >> >> Special relativity certainly cannot be used to justify the block universe >> concept. >> >> > That wasn't my question. Do you believe your experience rules out the > block universe? > > > No, neither do I believe that my experience necessitates a block universe > view. Special relativity renders the idea of global simultaneity otiose. So > global hypersurfaces of simultaneity make little sense. They make even less > sense in general relativity, where the local nature of the concept of time > is even more evident. > If personal experience has no weight (for either block time or presentism -- on this I agree), then why reject block time? Are there any theoretical motivations for doing so? Isn't the view of this universe as a spacetime the simplest theory consistent with the facts as we know them? I don't see what purpose fractionating spacetime into an infinite number of independent events serves beyond trying to cling to some notion of an evolving present (but even this it fails at if everything just becomes its own event). Do these events have any persistent existence or do they float in and out of reality? If they float in and out of reality--what additional facts can this explain? If none, why believe that they do? Jason -- You received this message because you are subscribed to the Google Groups "Everything List" group. 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