On 12/20/2018 4:37 PM, Jason Resch wrote:
On Thu, Dec 20, 2018 at 1:25 PM Brent Meeker <[email protected]
<mailto:[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] <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).
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.
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.
Brent
Jason
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