On Wed, Dec 19, 2018 at 10:40 PM Jason Resch <jasonre...@gmail.com> wrote:
> On Tue, Dec 18, 2018 at 11:14 PM Bruce Kellett <bhkell...@optusnet.com.au> > wrote: > >> From: Jason Resch <jasonre...@gmail.com> >> >> On Tue, Dec 18, 2018 at 7:27 PM Bruce Kellett <bhkellet...@gmail.com> >> wrote: >> >>> On Wed, Dec 19, 2018 at 12:19 PM Jason Resch <jasonre...@gmail.com> >>> wrote: >>> >>>> On Tue, Dec 18, 2018 at 6:45 PM Bruce Kellett <bhkellet...@gmail.com> >>>> wrote: >>>> >>>>> On Wed, Dec 19, 2018 at 11:27 AM Jason Resch <jasonre...@gmail.com> >>>>> wrote: >>>>> >>>>>> On Tue, Dec 18, 2018 at 6:05 PM Bruce Kellett <bhkellet...@gmail.com> >>>>>> wrote: >>>>>> >>>>>>> On Wed, Dec 19, 2018 at 11:02 AM Jason Resch <jasonre...@gmail.com> >>>>>>> wrote: >>>>>>> >>>>>>>> On Tue, Dec 18, 2018 at 3:23 PM John Clark <johnkcl...@gmail.com> >>>>>>>> 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? > Dynamics is the study of matter in motion. There are no clocks in arithmetic. > 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? > In what sense has this given up an objective global spacetime? All that has been abandoned is the concept of a universal time parameter which could give unique sense to global time slices. One can imagine such a foliation of space like hyper surfaces if one wants to, but it is not imposed by relativity. The problem with the "objective realist view" to which you seem to wish to cling is that not only is it not required by SR, it is positively ruled against by quantum mechanics, particularly non-local EPR-type correlations. 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 > Your person-duplicating thought experiments have no such drastic consequences -- there are other possibilities. > 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. > There are many presents. Each present is purely local. > 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. >> >> Of course not. There is no "present" for the whole of spacetime. I thought that was the point I was trying to make.The "present" is a local phenomenon. 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. > Yes. Isn't this the same as saying everything exists in the present? > No, because there is no such thing as a universal "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? > Why should there be an experiment that could distinguish these ideas? The point is that the block universe view is not a necessary consequence of SR. And it becomes even clearer that it is not a viable view when you take GR into account. > It isn't clear to me how those concepts even differ philosophically > speaking. > Of course they differ: in one case you have a purely local concept of the present; in the other case you require some global notion of a "present", which cannot even be uniquely defined. Bruce -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
