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.
For example, how do they effect one another?
Each one is affected by those in its past light cone.
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.
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". There is "here and then". There is "there and
then" But there is no "right now".
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.
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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