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?). 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. > > 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. > > > >> 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? > > The single currently firing neuron in your brain that was the last neuron > firing necessary for you to realize your conscious experience of reading > this e-mail? No other neurons, and no other human beings, nor any other > planets exist right now, because all that exists is the event that > immediately surrounds you? > > > That's why I've held that the concept of "observer moments" or > instantaneous states of consciousness is incoherent. Conscious thoughts > have a duration and they overlap one another, so there is an implicit arrow > of time in consciousness. > This issue goes away under mechanism. A computation can be distributed in space-time. Something like an Intel CPU is very much distributed over time, a distributed computation, involving multiple computers, or a parallel computation, such as with the brain, is distributed in time and space. So while a computation's implementation may have an extent through time and space, the computation itself is in a way outside of time and space. A computation, for instance has no: - mass - energy - location in space - location in time - unique identity (it can have many instantiations / realizations) Jason > > Brent > > > > > >> >> >>> 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. >> > > What is the extent of the local present?, 1 lightyear, 1kilometer, 1 > meter, 1 mm, 1 angstrom, 1 Plank length? > > >> >> 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 agree there is no universal present. > But you say each event has its own present. So each event exists in its > own present. If there is no single present but one for each local event, > then you might as well say ell presents exist, no? > > >> >> >>> 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. >> >> > > This would make "dynamics", an artifact of personal experience, not of the > objective reality. If you agree with me that block time is a possibility, > not ruled out by our experience, then our experience of a dynamically > evolving universe is compatible with a static block time universe too. > > This was the only point I was trying to get to. Platonic computations > exist timelessly, and change is only a subjective phenomenon of conscious > minds present within the structure that evolves over some dimension (be it > some *t* or a CPU's clock or counter) > > >> 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. >> >> > What exists? > > A: *naive presentism*: only a 3-dimensional space evolving in time (some > particular "slice" of spacetime exists, which constantly changes) > B: *local-presents*: Events, each in their position in space time, each > in their own present time > C: *block-time*: Events, each in their position in space time > > We both agree relativity rules out A. But I struggle to see the > difference between B and C (ontologically speaking), unless you are > proposing the view that the only thing that exists is a single event (I > don't think you are though). > > 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]. > To post to this group, send email to [email protected]. > Visit this group at https://groups.google.com/group/everything-list. > For more options, visit https://groups.google.com/d/optout. > > > -- > 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]. > To post to this group, send email to [email protected]. > Visit this group at https://groups.google.com/group/everything-list. > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "Everything List" group. 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