Julian Barbour (was: Re: objections to QTI)

2005-06-01 Thread Patrick Leahy
I read his book a year or so ago, so may be a bit hazy, but: Pour Bruno: he definitely does not want to talk about space-time capsules. Partly this is motivated by his metaphysical ideas about time, partly by the technicalities of the 3+1 (i.e. space+time, not persons!) approach to GR and

Re: Questions on Russell's Why Occam paper

2005-06-06 Thread Patrick Leahy
On Mon, 6 Jun 2005, Russell Standish wrote: I am beginning to regret calling the all descriptions ensemble with uniform measure a Schmidhuber ensemble. I think what I meant was that it could be generated by a standard dovetailer algorithm, running for 2^\aleph_0 timesteps. It can't!

Re: objections to QTI

2005-06-06 Thread Patrick Leahy
On Mon, 6 Jun 2005, Jesse Mazer wrote: Norman Samish wrote: If the universe started contracting, its entropy would get smaller, which nature doesn't allow in large-scale systems. This seems to me an argument in support of perpetual expansion. From what I've read, if the universe began

RE: where did the Big Bang come from?

2005-06-06 Thread Patrick Leahy
--in fact there is no agreed-upon answer to the question of what, if anything, came before the Big Bang or caused it. Patrick Leahy wrote: Maybe Norman is confusing the rather more legit idea that the fluctuations in the Big Bang, that explain why the universe is not completely uniform, come

Re: Can the arrow of time reverse?

2005-06-06 Thread Patrick Leahy
On Mon, 6 Jun 2005, Norman Samish wrote: Norman Samish wrote: If the universe started contracting, its entropy would get smaller, which nature doesn't allow in large-scale systems. This seems to me an argument in support of perpetual expansion. Norman Samish writes: Thank you for your

Re: Questions on Russell's Why Occam paper

2005-06-07 Thread Patrick Leahy
On Tue, 7 Jun 2005, Russell Standish wrote: Hal dealt with this one already, I notice. 2^\aleph_0 = c. \aleph_1 is something else entirely. d'oh! snip Now an observer will expect to find a SAS in one of the descriptions as a corrolory of the anthropic principle, which is explicitly

RE: Observer-Moment Measure from Universe Measure

2005-06-08 Thread Patrick Leahy
On Tue, 7 Jun 2005, Hal Finney wrote: Jonathan Colvin writes: There's a question begging to be asked, which is (predictably I suppose, for a qualia-denyer such as myself), what makes you think there is such a thing as an essence of an experience? I'd suggest there is no such thing as an

Re: Questions on Russell's Why Occam paper

2005-06-08 Thread Patrick Leahy
[Russell Standish wrote]: The AP is a statement that observed reality must be consistent with the observer being part of that reality. Famously, this can be interpreted as either a trivial tautology (Brandon Carter's original intention, I think), or an almost-obviously false principle of

Re: collapsing quantum wave function

2005-06-10 Thread Patrick Leahy
On Thu, 9 Jun 2005, Norman Samish wrote: Jonathan Colvin wrote: If I take a loaf of bread, chop it half, put one half in one room and one half in the other, and then ask the question where is the loaf of bread?, we can likely agree that the question is ill-posed. Depending on definitions,

Re: Questions on Russell's Why Occam paper

2005-06-10 Thread Patrick Leahy
On Thu, 9 Jun 2005, Russell Standish wrote: Yes, if you think there is a concrete reality in which everything exists (your question of where does the observer live?), then the AP is a tautology. What I meant by where does the observer live, in more formal language, is how do you account

Re: Smullyan Shmullyan, give me a real example

2006-05-10 Thread Patrick Leahy
On who invented quantum suicide, the following is from the biography of Hugh Everett by Eugene B. Shikhovtsev and Kenneth W. Ford, at http://space.mit.edu/home/tegmark/everett/ Atheist or not, Everett firmly believed that his many-worlds theory guaranteed him immortality: His consciousness,

Re: Smullyan Shmullyan, give me a real example

2006-05-12 Thread Patrick Leahy
On Fri, 12 May 2006, Saibal Mitra wrote: Einstein seems to have believed in ''immortal observer moments''. In a BBC documentary about time it was mentioned that Einstein consoled a friend whose son had died in a tragic accident by saying that relativity suggests that the past and the

JOINING

2005-05-18 Thread Patrick Leahy
Hi, I'm Paddy Leahy. I'm an astrophysicist and observational cosmologist with a long-standing interest in the foundations of QM. == Dr J. P. Leahy, University of Manchester, Jodrell Bank Observatory, School of Physics Astronomy, Macclesfield,

Many Pasts? Not according to QM...

2005-05-18 Thread Patrick Leahy
I've recently been reading the archive of this group with great interest and noted a lot of interesting ideas. I'd like to kick off my contribution to the group with a response to a comment made in numerous posts that a single observer-moment can have multiple pasts, including macroscopically

Re: Many Pasts? Not according to QM...

2005-05-18 Thread Patrick Leahy
On Wed, 18 May 2005, Quentin Anciaux wrote: Le Mercredi 18 Mai 2005 17:57, Patrick Leahy a écrit : SNIP Of course, many of you (maybe all) may be defining pasts from an information-theoretic point of view, i.e. by identifying all observer-moments in the multiverse which are equivalent as perceived

Re: Many Pasts? Not according to QM...

2005-05-18 Thread Patrick Leahy
On Wed, 18 May 2005, Hal Finney wrote: Does anybody believe that this is consistent with the many-worlds interpretation of QM? First, welcome to the list. Thanks! SNIP However, particularly as we look to larger ensembles than just the MWI, it becomes attractive to define observers and

Re: WHY DOES ANYTHING EXIST

2005-05-19 Thread Patrick Leahy
I find this a very odd question to be asked on this list. To me, one of the main attractions of the everything thesis is that it provides the only possible answer to this question. Viz: as Jonathan pointed out, mathematical objects are logical necessities, and the thesis (at least in Tegmark's

White Rabbit vs. Tegmark

2005-05-22 Thread Patrick Leahy
I looked into this mailing list because I thought I'd come up with a fairly cogent objection to Max Tegmark's version of the everything thesis, i.e. that there is no distinction between physical and mathematical reality... our multiverse is one particular solution to a set of differential

Re: White Rabbit vs. Tegmark

2005-05-22 Thread Patrick Leahy
On Mon, 23 May 2005, Russell Standish wrote: I think most of us concluded that Tegmark's thesis is somewhat ambiguous. One interpretation of it that both myself and Bruno tend to make is that it is the set of finite axiomatic systems (finite sets of axioms, and recusively enumerated

Re: Sociological approach

2005-05-23 Thread Patrick Leahy
On Sun, 22 May 2005, rmiller wrote: I'm approaching this as a sociologist with some physics background so I'm focusing on what the behavior system perceives (measures). If all possible worlds exist in a superpositional state, then the behavior system should likewise exist in a

Re: White Rabbit vs. Tegmark

2005-05-23 Thread Patrick Leahy
On Sun, 22 May 2005, Hal Finney wrote: Regarding the nature of Tegmark's mathematical objects, I found some old discussion on the list, a debate between me and Russell Standish, in which Russell argued that Tegmark's objects should be understood as formal systems, while I claimed that they

Re: Sociological approach

2005-05-23 Thread Patrick Leahy
QM is a well-defined theory. Like any theory it could be proved wrong by future experiments. My point is that R. Miller's suggestions would definitely constitute a replacement of QM by something different. So would aet.radal's (?) suggestion of information tunnelling between macroscopic

Re: Decoherence and MWI

2005-05-23 Thread Patrick Leahy
On Mon, 23 May 2005, Hal Finney wrote: I'd like to take advantage of having a bona fide physicist on the list to ask a question about decoherence and its implications for the MWI. SNIP If this is true, then how can a physicist not accept the MWI? Beats me... Isn't that just a matter of

Re: Sociological approach

2005-05-23 Thread Patrick Leahy
On Mon, 23 May 2005, scerir wrote: Do you agree we can have branches (or histories) in space (in a space) but also branches (or histories) in time? I guess there is an implicit not only in this question :) You have an atom, excited (ie by a laser). This atom can radiate a photon in two

Re: White Rabbit vs. Tegmark

2005-05-23 Thread Patrick Leahy
On Mon, 23 May 2005, Bruno Marchal wrote: SNIP Concerning the white rabbits, I don't see how Tegmark could even address the problem given that it is a measure problem with respect to the many computational histories. I don't even remember if Tegmark is aware of any measure relating the

Re: White Rabbit vs. Tegmark

2005-05-23 Thread Patrick Leahy
On Mon, 23 May 2005, Hal Finney wrote: I've overlooked until now the fact that mathematical physics restricts itself to (almost-everywhere) differentiable functions of the continuum. What is the cardinality of the set of such functions? I rather suspect that they are denumerable, hence exactly

RE: Sociological approach

2005-05-24 Thread Patrick Leahy
On Mon, 23 May 2005, Brent Meeker wrote: -Original Message- From: Patrick Leahy [mailto:[EMAIL PROTECTED] SNIP NB: I'm in some terminological difficulty because I personally *define* different branches of the wave function by the property of being fully decoherent. Hence reference

RE: Sociological approach

2005-05-24 Thread Patrick Leahy
On Tue, 24 May 2005, aet.radal ssg wrote: See http://decoherence.de ? It was good for a laugh, not much else. Funnily enough, that was my thought about your friend Plaga, whose paper is rubbish because he doesn't know the first thing about decoherence, and fails to notice that his

Re: White Rabbit vs. Tegmark

2005-05-24 Thread Patrick Leahy
On Tue, 24 May 2005, Alastair Malcolm wrote: Perhaps I can throw in a few thoughts here, partly in the hope I may learn something from possible replies (or lack thereof!). - Original Message - From: Patrick Leahy [EMAIL PROTECTED] Sent: 23 May 2005 00:03 . SNIP

Re: Hamel Basis

2005-05-24 Thread Patrick Leahy
I know this one! I had a friend who published a magazine called Zorn printed on pale yellow paper... ;) Paddy Leahy

Re: Observables, Measurables, and Detectors

2005-05-25 Thread Patrick Leahy
It looks as though you advocate a role for each of these: observables measurements detectors and for all I know observers It seemed to me that MWI allowed me to get away with a considerable simplification. Gone were observers and even observations. Even measurements, I discard.

RE: White Rabbit vs. Tegmark

2005-05-25 Thread Patrick Leahy
On Wed, 25 May 2005, Stathis Papaioannou wrote: SNIP Consider these two parallel arguments using a version of the anthropic principle: (a) In the multiverse, those worlds which have physical laws and constants very different to what we are used to may greatly predominate. However, it is no

Re: Induction vs Rubbish

2005-05-25 Thread Patrick Leahy
On Wed, 25 May 2005, Russell Standish wrote: On Tue, May 24, 2005 at 10:10:19PM +0100, Patrick Leahy wrote: Lewis also distinguishes between inductive failure and rubbish universes as two different objections to his model. I notice that in your articles both you and Russell Standish more

Re: Induction vs Rubbish

2005-05-25 Thread Patrick Leahy
On Wed, 25 May 2005, Benjamin Udell wrote: The induction-friendly universe with so much detectable rubbish that a wide variety of phenomena cannot be unified into a simple theory sounds like a universe where induction works but surmise, or inference to the simplest explanation, faces grave

Re: White Rabbit vs. Tegmark

2005-05-26 Thread Patrick Leahy
On Thu, 26 May 2005, Alastair Malcolm wrote: An example occurs which might be of help. Let us say that the physics of the universe is such that in the Milky Way galaxy, carbon-based SAS's outnumber silicon-based SAS's by a trillion to one. Wouldn't we say that the inhabitants of that galaxy

RE: White Rabbit vs. Tegmark

2005-05-26 Thread Patrick Leahy
On Thu, 26 May 2005, Brent Meeker wrote: I agree with all you say. But note that the case of finite sets is not really any different. You still have to define a measure. It may seem that there is one, compelling, natural measure - but that's just Laplace's principle of indifference

Re: Plaga

2005-05-27 Thread Patrick Leahy
As an exercise I've been trying to pinpoint exactly what is wrong with Plaga's paper. For anyone who doubts that it *is* wrong, note that it proposed 10 years ago an experiment which he said was feasible with what was then state-of-the-art equipment. This technology has now massively