On 07 Feb 2014, at 21:05, Edgar L. Owen wrote:
Jesse,
I'm willing to accept the notion that time, like everything else is
quantized at the finest scale, but even so I would maintain that
everything is at one and only one point in time as the current state
is continually recomputed into the next state..
However it seems to me this not just a simple sequence of
information states being computed by programatic operators, but that
the information that constitutes the current state of the universe
must include information about how that information is changing. Not
sure if that's clear. A lot more about it in my book where I explore
the details of the information universe.
As log as you don't define what you mean by "computation" this is
nonsense.
Bruno
Also the notion that the arrow of time has anything to do with the
2nd law of thermodynamics doesn't make any sense at all. Entropy
varies widely in the universe. If it had anything to do with the
arrow of time we could expect time to flow differently in areas of
different entropy and backwards in areas of decreasing entropy which
it of course doesn't.
Edgar
On Friday, February 7, 2014 1:01:54 PM UTC-5, jessem wrote:
On Fri, Feb 7, 2014 at 12:40 PM, Edgar L. Owen <[email protected]>
wrote:
Jesse,
BTW, your own operational definition proves that time flows. Because
your reflected light will always arrive back to you later on your
clock than when it was sent.
And how does that prove that time "flows" in a non-block-timey
sense? From a geometric point of view, it just means that if you
have a v-shaped path through spacetime of a light signal that
intersects my worldline at two different points, then those two
events have different proper times on my clock (because naturally,
*any* two distinct points on my worldline have distinct proper
times). If you're just talking about the fact that the event of the
signal being sent always happens at an earlier proper time than the
event of it being received, that's ultimately a consequence of the
thermodynamic arrow of time and the fact that the entropy of the
universe is continually increasing from a low-entropy Big Bang--if
the laws of physics are deterministic it would in principle be
possible to set up a special set of initial conditions for an
isolated system that would ensure entropy would decrease towards a
future minimum rather than increase, and in such a system there
would be time-reversed signal "reception" events that happened
before time-reversed "transmission" events.
Jesse
On Friday, February 7, 2014 8:49:32 AM UTC-5, jessem wrote:
On Fri, Feb 7, 2014 at 7:57 AM, Edgar L. Owen <[email protected]> wrote:
Jesse,
OK, here's the detailed analysis of how I see the current state of
this issue that I promised:
A few points:
1. Since you asked let me repeat my 'operational definition' of the
present moment that I used before. The twins meet, shake hands and
compare watches. That is the operation definition.
That is essentially the same as your reflected light operational
definition with which I have no problem.
2. However it is important to note that that works not just for the
twins together, but for every single twin by himself. Because any
twin or observer can shake his own hand, look at his own watch, or
note that the light reflected from a mirror in his hand takes
minimal time to return.
Therefore what is true for the twins together is also true for each
twin separately, and is true for every observer in the universe as
well.
3. So what is it that is true? You say it is "being at the same
point in spacetime". Call that relationship R1. I use the term that
everyone else does and has throughout history, namely "being in the
(same) present moment". Call that relationship R2.
So let's use a thought experiment to examine the difference between
R1 and R2:
Imagine a line of a billion twins. By both our definitions every two
adjacent twins will be in what you call relationship R1 and I call
R2. And this will be true of the adjacent twins on both sides of
every twin.
In your terminology every twin will be "at the same point of
spacetime" with both the one to the right and to the left.
In my terminology every twin will be "in the same present moment"
with both the one to the right and to the left.
Note that these relationships are transitive, so they necessarily
cascade through the whole line of twins. What that means is that
twin #1 must have that same relationship with twin #1 billion.
But clearly it is NOT true that twin 1 is "at the same point in
spacetime" as twin 1 billion because he not at the same point in
space. However twin 1 can be in the same present moment as twin 1
billion, because that is just a time relationship that does not
require a same space location.
Thus our agreed operational definition leads to a contradiction with
your terminology but not mine.
Well, in my discussion I believe I alternated between two subtly
different definitions--one which said the light-signal-return-time
actually went to zero, and another which said that it was
"negligible". The first definition was an ideal theoretical
description--and if the twins in your thought-experiment were ideal
point-like observers who could literally have the time delay of
light signals approach zero at the moment on each of their clocks
where they met, then you could have a billion of them meeting in
such a way and the fact of delay time approaching zero would really
be completely transitive. But the second definition was just an
approximate practical one. "Negligible" is obviously a fuzzy term
which depends on how precise your instruments are--if the twins are
standing 0.3 meters apart and they use the light test, a
sufficiently sensitive instrument will reveal it actually takes
about 2 nanoseconds between emitting a light flash and getting back
the reflection. Likewise if they shake hands, sufficiently good
equipment would show a much larger delay between the moment their
hands touch and the moment the train of nerve impulses set off by
the touch reaches the brain (and the atoms of their hands don't
really "touch", so there would even be some sub-nanosecond delay
between a motion in an atom in the palm of one hand and its effect
on the motion of an atom in the palm of the other hand). For a
normal experiment like the twin paradox, we won't get any noticeably
inaccurate results if we model them as meeting at the same point in
spacetime when sufficiently accurate measurements might show them a
light-nanosecond apart. But your row-of-twins scenario is obviously
constructed in a way where we'll get wrong conclusions if we treat
"negligible" the same as "zero", since if you stack up a bunch of
zeros you still always get zero, but if you stack up a bunch of
"negligible, unmeasurable" differences you eventually get a
measurable difference.
I'm sure you would run into the same problem if I asked you for a
practical operational definition of "same point in space"--any such
practical difference is going to ignore very small gaps that are too
small for our measuring-instruments to discern (or just aren't worth
worrying about in our calculations), but obviously if you stack up a
sufficient number of small things with small spatial gaps you may
get an arbitrarily large spatial distance between both ends of the
stack.
Now one final point: You criticize me for relying on "conscious
experience" presumably when it comes to the twins shaking hands and
comparing watches.
No, when I talked about "conscious experience" I meant the vague
qualitative sense we have that time seems to "flow", that things
seem to come into existence (from our perspective at least) and go
out of them. I didn't mean the perceptions of well-defined
experiments that anyone can observe the result of from the outside
without knowing anything about the inner experience of the person
performing it, like a comparison of watches or a shaking of hands.
Jesse
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