Hitoshi Kitada (hitoshi@kitada.com)
Thu, 30 Sep 1999 18:29:28 +0900
Dear Stephen,
Stephen P. King <stephenk1@home.com> wrote:
Subject: [time 835] Re: FW: [time 830] Re: Does a fundamental time exist in GR
and QM? The thinking of others...
> Dear Lance,
>
> I was trying to get some thinking focussed on the key issue: time and
> how it is thought of. I too am interested in how Hitoshi contrasts his
> notions with those of people like Baez.
Your quotation of Baez did not suffice me to respond because I am not
interested in his confined viewpoint. Lance's quotation of Paul Stewart
Snyder's post was necessary for me to see your post.
> One problem that I see, is that
> it is assumed that there exist only one space-time manifold in which all
> observers are embedded. This is a very old notion and remains
> unquestioned!
> We need to consider the implications of LS theory with regards to this!
> I believe that each LS would define its own space-time,
Yes.
> both in terms of
> the causal behavior of its observations and the group theoretical
> behavior thereof. We can take a clue from the ideas were geometries were
> defined by the algebraic properties of systems and not by some a priori
> given.
> We need to talk about clocking! We need to figure out a clear and
> concise definition that is applicable at any level of complexity. I feel
> that it will relate directly to what observation is in a
> non-anthropocentric fashion. :-)
> I cut and pasted your post [time 833]] below.
>
>
> Lancelot Fletcher wrote:
> >
> > Dear Stephen,
> >
> > > -----Original Message-----
> > > From: Stephen P. King [mailto:stephenk1@home.com]
> > > Sent: Wednesday, September 29, 1999 6:50 AM
> > > To: Lancelot Fletcher
> > > Subject: Re: FW: [time 830] Re: Does a fundamental time exist in GR and
> > > QM? The thinking of others...
> > >
> > >
> > > Dear Lance,
> > >
> > > Here is the Deja-News URL for the thread. It is titled: "Does a
> > > fundamental time exist in GR and QM?".
> > >
> >
> > As you have most likely noticed by now, I already found that thread via
> > deja-news myself. I found the message you posted rather interesting,
> > although I am still not clear why you chose that particular one to post.
I
> > have not had a chance to read the entire thread, but, as I said in [time
> > 833], I think the first message in the thread bears some resemblance to
> > some of the ways in which Hitoshi has formulated his project. By posting
> > it on Hitoshi's time list I am hoping to prompt Hitoshi to say something
> > that would clarify the background of his thinking.
> >
> > Lance
>
> Subject: [time 833] RE: [time 830] Re: Does a fundamental time exist in
> GR and QM? The thinking of
> others...
> Date: Wed, 29 Sep 1999 02:09:40 -0500
> From: "Lancelot Fletcher" <lance.fletcher@freelance-academy.org>
> To: <stephenk1@home.com>, <time@kitada.com>
>
>
>
>
> Stephen,
>
> > -----Original Message-----
> > From: owner-time@kitada.com [mailto:owner-time@kitada.com]On Behalf Of
> > Stephen Paul King
> > Sent: Tuesday, September 28, 1999 9:28 PM
> > To: time@kitada.com
> > Subject: [time 830] Re: Does a fundamental time exist in GR and QM? The
> > thinking of others...
>
> I was a little puzzled about why you re-posted that message by John Baez
> which was originally posted on Aug. 12 on the sci.physics.research
> newsgroup as message 112 in a thread containing 119 messages. Out of
> curiosity I tracked down the first message in that thread, from Paul
> Stewart Snyder on Aug. 6, and I have copied it below. It seems to me
> that
> some of this, especially the second paragraph, resembles Hitoshi's
> approach
> in ways that might be worth exploring.
>
> Lance
>
> ===================================
>
> From: "Paul Stewart Snyder" <ps@ws5.com>
> Subject: Does a fundamental time exist in GR and QM?
> Date: 06 Aug 1999 00:00:00 GMT
> Message-ID: <rqe8crihq1tcq6@corp.supernews.com>
> Approved: mmcirvin@world.std.com (sci.physics.research)
> Sender: mmcirvin@world.std.com (Matthew J McIrvin)
> Organization: Posted via Supernews, http://www.supernews.com
> Newsgroups: sci.physics.research
>
> I have tried to digest the basic information in the recent threads about
> spacetime in GR. To me the most interesting ideas follow from what Carlo
> Rovelli suggested in 1991 (Physical Review D43, 442), that in GR time
> should be treated as a derived and not a fundamental quantity. In
> extending this
> to the quantum world, he argues that "in the absence of a fundamental
> time and
> of an exact Schrodinger equation, there are gauge invariant observables,
> that commute with the hamiltonian constraint, which describe evolution
> with
> respect to physical clocks. The observables are self-adjoint operators
> on
> the space of the solutions of the Wheeler-DeWitt equation.. Evolution
> with
> respect to physical clocks is described by self-adjoint operators
> corresponding to the observables.. This extension is well-defined both
> in
> terms of the coherence of the formalism, and from the point of view of
> the
> viability of the standard probabilistic interpretation."
>
> It seems to me that rethinking the answers to the questions about what
> is
> "here and now" and what is "casuality", in terms of spatial contiguity
> in
> an atemporal universe, might resolve some of the apparent paradoxes of
> GR/QM?
> Indeed, the idea of hamiltonian mechanics in a presymplectic space seems
> "elegant" and, if this actually models nature, might provide a useful
> way
> of viewing phenomena that seem to lack temporal constraints.
Symplectic structure appears when one considers a dynamical system with
constraints, e.g., constraints to Minkowski manifold. Thus Snyder here refers
to QM without any constraints. So I guess he is speaking about the usual QM in
Euclidean space.
In this sense, his view looks quite close to mine. He should have developed
his idea further enough to be appreciated by the people in the news group.
Then he might have gotten other responses.
> Are there
> any
> clear objections or impediments in pursuing this approach?
> ****
>
> We think of a clocking as an act of observation within LS theory, as I
> interprete it; so we distinguish observables from observers in the sense
> of subject and object... We need to think about causality! What is
> "presymplectic space"?
>
> Later,
>
> Stephen
>
Best wishes,
Hitoshi
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