RE: Reversible computing
Assuming neurons aren't able to tap into QM stuff because of decoherence, it seems odd that consciousness is performed with an irreversible computation whilst the universe uses a reversible computation. - David -Original Message- From: Russell Standish [mailto:[EMAIL PROTECTED] Sent: Thursday, 13 November 2003 9:59 AM To: David Barrett-Lennard Subject: Re: Reversible computing I think the answer to your question is yes (assuming I understand you correctly). Information and probability are closely linked (through algorithmic information theory - AIT for those acronym lists). Schroedinger's equation is known to conserve probability (basically |\psi(t)| is a constant - usually set to 1 - under evolution by Schroedinger's equation (|.| here means Hilbert spoace norm, not absolute value)). This conservation of probability turns out to be equivalent to unitarity of the Hamiltonian operator, which guess what, means energy is conserved. Unitary evolution is a reversible computation, which is why quantum computations are reversible. Cheers David Barrett-Lennard wrote: I have been wondering whether there is something significant in the fact that our laws of physics are mostly time symmetric, and we have a law of conservation of mass/energy. Does this suggest that our universe is associated with a reversible (and information preserving) computation? - David A/Prof Russell Standish Director High Performance Computing Support Unit, Phone 9385 6967, 8308 3119 (mobile) UNSW SYDNEY 2052 Fax 9385 6965, 0425 253119 () Australia[EMAIL PROTECTED] Room 2075, Red Centre http://parallel.hpc.unsw.edu.au/rks International prefix +612, Interstate prefix 02
Re: Reversible computing
Dear David, Have you read any of the books by Michael C. Mackey on the implications of reversible (invertible) and non-invertible systems? Some, notably Oliver Penrose, have attacked his reasoning, but I find his work to be both insightful and novel and that his detractors are mostly driven by their own inabilities to take statistical dynamics and thermodynamics forward. Mackey shows that invertible dynamical system will be at equilibrium perpetually and that only non-invertible system will exhibit an "arrow of time". I am very interested in the subject of reversible computation, as it relates to my study of Hitoshi Kitada's theory of Time,and would like tolearn aboutwhat you have found about them. Kindest regards, Stephen - Original Message - From: David Barrett-Lennard To: [EMAIL PROTECTED] Sent: Wednesday, November 12, 2003 8:36 PM Subject: Reversible computing I have been wondering whether there is something significant in the fact that our laws of physics are mostly time symmetric, and we have a law of conservation of mass/energy. Does this suggest that our universe is associated with a reversible (and information preserving) computation? - David
Re: Reversible computing
Not so strange. The process of conscious observation creates information. Reversible computations conserve information. Therefore conscious processes must be irreversible. A corrollory of this is that conscious observers will experience an arrow of time, including a second law of thermodynamics. Cheers David Barrett-Lennard wrote: Assuming neurons aren't able to tap into QM stuff because of decoherence, it seems odd that consciousness is performed with an irreversible computation whilst the universe uses a reversible computation. - David -Original Message- From: Russell Standish [mailto:[EMAIL PROTECTED] Sent: Thursday, 13 November 2003 9:59 AM To: David Barrett-Lennard Subject: Re: Reversible computing I think the answer to your question is yes (assuming I understand you correctly). Information and probability are closely linked (through algorithmic information theory - AIT for those acronym lists). Schroedinger's equation is known to conserve probability (basically |\psi(t)| is a constant - usually set to 1 - under evolution by Schroedinger's equation (|.| here means Hilbert spoace norm, not absolute value)). This conservation of probability turns out to be equivalent to unitarity of the Hamiltonian operator, which guess what, means energy is conserved. Unitary evolution is a reversible computation, which is why quantum computations are reversible. Cheers David Barrett-Lennard wrote: I have been wondering whether there is something significant in the fact that our laws of physics are mostly time symmetric, and we have a law of conservation of mass/energy. Does this suggest that our universe is associated with a reversible (and information preserving) computation? - David A/Prof Russell StandishDirector High Performance Computing Support Unit, Phone 9385 6967, 8308 3119 (mobile) UNSW SYDNEY 2052 Fax 9385 6965, 0425 253119 () Australia [EMAIL PROTECTED] Room 2075, Red Centre http://parallel.hpc.unsw.edu.au/rks International prefix +612, Interstate prefix 02 A/Prof Russell Standish Director High Performance Computing Support Unit, Phone 9385 6967, 8308 3119 (mobile) UNSW SYDNEY 2052 Fax 9385 6965, 0425 253119 () Australia[EMAIL PROTECTED] Room 2075, Red Centrehttp://parallel.hpc.unsw.edu.au/rks International prefix +612, Interstate prefix 02
RE: Reversible computing
I havent read much about invertible systems. Curiously though, earlier this year I was working on a difficult problem related to optimistic concurrency control in a distributed object oriented database Im developing, and found that I only solved it when I decomposed it as an invertible problem into parts that were invertible. The decomposition always involved invertible functions with two inputs and two outputs. All state changes (to a local database) are applied as invertible operations, and the problem is to transform operations so they can be applied in different orders at different sites and yet achieve convergence. I guess its unlikely that this has relevance to physics. - David -Original Message- From: Stephen Paul King [mailto:[EMAIL PROTECTED] Sent: Thursday, 13 November 2003 10:14 AM To: [EMAIL PROTECTED] Subject: Re: Reversible computing Dear David, Have you read any of the books by Michael C. Mackey on the implications of reversible (invertible) and non-invertible systems? Some, notably Oliver Penrose, have attacked his reasoning, but I find his work to be both insightful and novel and that his detractors are mostly driven by their own inabilities to take statistical dynamics and thermodynamics forward. Mackey shows that invertible dynamical system will be at equilibrium perpetually and that only non-invertible system will exhibit an arrow of time. I am very interested in the subject of reversible computation, as it relates to my study of Hitoshi Kitada's theory of Time, and would like to learn about what you have found about them. Kindest regards, Stephen - Original Message - From: David Barrett-Lennard To: [EMAIL PROTECTED] Sent: Wednesday, November 12, 2003 8:36 PM Subject: Reversible computing I have been wondering whether there is something significant in the fact that our laws of physics are mostly time symmetric, and we have a law of conservation of mass/energy. Does this suggest that our universe is associated with a reversible (and information preserving) computation? - David
