On 12/20/2018 1:38 AM, Jason Resch wrote:
On Wed, Dec 19, 2018 at 5:51 PM Brent Meeker <[email protected]
<mailto:[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] <mailto:[email protected]>> wrote:
On Wed, Dec 19, 2018 at 10:40 PM Jason Resch
<[email protected] <mailto:[email protected]>> wrote:
On Tue, Dec 18, 2018 at 11:14 PM Bruce Kellett
<[email protected]
<mailto:[email protected]>> wrote:
From: *Jason Resch* <[email protected]
<mailto:[email protected]>>
On Tue, Dec 18, 2018 at 7:27 PM Bruce Kellett
<[email protected]
<mailto:[email protected]>> wrote:
On Wed, Dec 19, 2018 at 12:19 PM Jason Resch
<[email protected]
<mailto:[email protected]>> wrote:
On Tue, Dec 18, 2018 at 6:45 PM Bruce
Kellett <[email protected]
<mailto:[email protected]>> wrote:
On Wed, Dec 19, 2018 at 11:27 AM Jason
Resch <[email protected]
<mailto:[email protected]>> wrote:
On Tue, Dec 18, 2018 at 6:05 PM
Bruce Kellett <[email protected]
<mailto:[email protected]>> wrote:
On Wed, Dec 19, 2018 at 11:02 AM
Jason Resch
<[email protected]
<mailto:[email protected]>>
wrote:
On Tue, Dec 18, 2018 at 3:23
PM John Clark
<[email protected]
<mailto:[email protected]>>
wrote:
Arithmetical
computationsdon'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).
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.
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?
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.
Brent
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
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