On Thu, Dec 20, 2018 at 10:27 PM Brent Meeker <[email protected]> wrote:
> > > On 12/20/2018 4:37 PM, Jason Resch wrote: > > > > On Thu, Dec 20, 2018 at 1:25 PM Brent Meeker <[email protected]> wrote: > >> >> >> On 12/20/2018 1:38 AM, Jason Resch wrote: >> >> >> >> On Wed, Dec 19, 2018 at 5:51 PM Brent Meeker <[email protected]> >> wrote: >> >>> >>> >>> On 12/19/2018 4:31 AM, Jason Resch wrote: >>> >>> >>> >>> On Wed, Dec 19, 2018 at 6:00 AM Bruce Kellett <[email protected]> >>> wrote: >>> >>>> On Wed, Dec 19, 2018 at 10:40 PM Jason Resch <[email protected]> >>>> wrote: >>>> >>>>> 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? >>>>> >>>> >>>> Dynamics is the study of matter in motion. There are no clocks in >>>> arithmetic. >>>> >>> >>> Matter only moves with respect to different times, likewise the state of >>> a computer's registers and memory only change between steps of a CPU. You >>> could study the dynamics of state changes in a computer. >>> >>> >>>> >>>> >>>>> 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. >>>> >>> >>> But relativity does rules out "naive presentism" -- the idea that there >>> are is an objective spacelike hypersurfaces that we can call a present. You >>> seem to agree with me on this. What I am struggling with is the >>> interpretation of time, or of the present, when you reduce present moments >>> to single points in space time. What does this buy you? It seems to make >>> it much harder to talk about the *relationship* between remote points >>> in space time. >>> >>> >>> It's easy: They are spacelike, pastlike, or futurelike. >>> >> >> But as you and Bruce have said recently, the present is not space-like, >> but must be localized to a single point (or do you disagree with this?). >> >> >> You referred to talk about *RELATIONSHIP* between points in spacetime. >> Space-like is a *relationship* between two points (events). >> > > So what constitutes the present, in your view? Is there such a thing? If > so, what does it contain? > > > There is no such thing as "the present", there are just events, which you > could approximate a little and give some local extension based on what > process you're modeling. The closest thing to "the present" in a global > sense would be the local comoving frame in which the cosmic microwave > background is isotropic. But that's not very sharply defined locally. > > > >> >> >> What dimensionality do you assing to pastlike and futurelike? >> >> >>> >>> >>> For example, how do they effect one another? >>> >>> >>> Each one is affected by those in its past light cone. >>> >> >> A past light come is a space-time (4-d volume). This gets you back to >> the Andromeda paradox (two observers crossing each other on the sidewalk >> share different past and future light cones which contain different >> ontologies. >> >> >> No, light cones are invariants. The two observers have the same past and >> future lightcones as they pass on the sidewalk. >> > > If the two observers are moving, then in the past they were in different > locations, and belonged to different past lightcones. Their past (and > future) lightcones would be at an angle to each other, would they not? > Isn't it the case they will only share a past light cone if they are in the > same location and have the same reference frame? > > > You specified "two observers crossing each other", with I took to mean > they were at the same event. An event has a unique light cone. The motion > makes no difference, light cones don't tilt. > > Ahh okay. I think I understand now. Thanks for the correction. > > >> >> >> >>> >>> How can one talk about machines (such as our own brains) which are >>> extended in space time, when we can only talk about individual atoms, or >>> neurons existing in their own present, when they must interact with other >>> neurons whose signal remains but that neuron now no longer exists (being in >>> its own present time different from the perspective of the neuron which >>> received its signal). It just seems so much more complicated to add the >>> notion of popping into and out of existence, when it is wholly unnecessary >>> and adds nothing to the theory. >>> >>> >>> There's no problem with considering those events in the past light cone >>> as affecting each event. >>> >> >> Except when it comes to saying whether those things exist. >> >> >> What's the problem with saying events in the past light cones exist, or >> did exist? >> >> > Nothing, my only problem is saying those things have stopped existing. > > >> >> >>> >>> >>> >>>> 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. >>>> >>> >>> I don't agree EPR has any bearing on this topic, but also don't want to >>> re-open that can of worms here. >>> >>> >>>> >>>> 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. >>>> >>>> >>> >>> I would like to hear what they are, as I am not aware of them. >>> >>> >>>> 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. >>>> >>> >>> So ontologically speaking, all that exists right now is what? >>> >>> >>> There is "here and now". >>> >> >> So a single Plank-length volume. (or if it is not a Plank-length volume, >> please tell me how large the spatial extent of "here" is) >> >> >>> There is "here and then". >>> >> >> A past-light-line (not a cone?) >> >> >>> There is "there and then" >>> >> >> It doesn't/never existed? >> >> >>> But there is no "right now". >>> >>> >> So nothing exists but the current local Plank-time point? >> >> >> You're just playing with words. There is no "right now" because the >> concept has no definite reference. It doesn't imply that distant events >> don't exist. >> >> > Why can't "right now" refer to a slice through spacetime, and each > observer in each reference frame can have a different conception of what > the contents of "right now" includes? > > > It depends on the observers motion. How can you determine that motion and > motion relative to what? Hence my reference to the CMB above. But that's > only an average reference frame, so it will be poorly defined at distance. > > > I am not advocating any global reference frame, just mentioning that for a particular observe, they can define a present that works for them (in their own reference frame). From their point of view they can consider themselves at rest (whether they are or are not). Jason -- 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 [email protected]. 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