From cbmvax!uunet!Think.COM!gls Fri Mar  1 13:31:03 1991
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Date: Fri Mar 1 13:31:03 1991
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From: Guy Steele <cbmvax!uunet!Think.COM!gls>
Message-Id: <9102282126.AA15199@beethoven.think.com>
To: protin@PICA.ARMY.MIL
Cc: gls@Think.COM, jsp@milton.u.washington.edu, lojban-list@snark.thyrsus.com
In-Reply-To: "Arthur W. Protin Jr." (GC-ACCURATE)'s message of Thu, 28 Feb 91 12:10:28 EST <9102281210.aa11994@COR4.PICA.ARMY.MIL>
Subject:  Punctuation & relativistic tense.
Status: RO

   Date:     Thu, 28 Feb 91 12:10:28 EST
   From: "Arthur W. Protin Jr." (GC-ACCURATE) <protin@PICA.ARMY.MIL>

   Guy, & others,
       You said:
   > No, you have fallen into a trap here: the use of the word "state"
   > begs the question.  Implicit in the word "state" is the notion that
   > you are taking a "snapshot" of the entire universe *at the same point
   > in time everywhere*--but that is exactly the notion we are trying to
   > get a grip on!  Observers in different inertial frames will differ on
   > what constitutes a state.

   here you say that states are subjective but then immediately you go on
   wtih:


   > What is a state?  It is the minimal amount of information needed to
   > imply future states (assuming determinism--here I ignore quantum
   > mechanics).  ....

   The various subjective states that you refered to are misdirection!

Yes; I was sloppy in making a transition and I am sorry I confused
you.  In effect, I first cited the "intuitive" notion of state (a
snapshot) and pointed out that that this definition will not do
because it is observer-dependent.  I then proceeded, in the paragraph
beginning "What is a state?", to appeal to a more basic intuition
about state without recourse to the notion of global simultaneity
that is implicit in the word "snapshot"; then I used this more basic
intuition to *redefine* the word state so as to have an
observer-independent meaning.  Note that such states do not have
unique successors; they are only partially ordered, not totally
ordered.  State X is earlier than state Y if and only if there do not
exist two events x (in X) and y (in Y) such that x lies within the
future-light-cone of y.

   There is either determinism (and we can keep our physics) or there isn't.
   I will assume for at least this lifetime that there is determinism!

   Only one state description will correctly imply the future.  That state
   description is one of a sequence that is the absolute time reference.

This is the flaw in your reasoning.  In a relativistic theory,
observer-independent states are not totally ordered, only partially
ordered.

   That we can not measure, observe, or even correctly infer those
   state descriptions will not deter me from the belief in their existance.
   (A much more compelling proof on their non-existance will be required
   to move me.)

   Now what proof have you that we can not ever infer the "true and absolute"
   event sequence for the events we do observe?

--Guy Steele