From: Anders Sandberg <asa@nada.kth.se>

Date: Thu Feb 11 1999 - 04:50:21 PST

Date: Thu Feb 11 1999 - 04:50:21 PST

Damien Broderick <damien@ariel.ucs.unimelb.edu.au> writes:

*> Truly mindboggling article about the work of Roy Frieden on Fisher
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*> information and the basic laws of physics (there's not much abt him on the
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*> Web), at
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*>
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*> http://www.newscientist.com/ns/19990130/iisthelaw.html
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*>
*

*> I'd like to see some informed discussion from the mathematics and
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*> physicists on this topic.
*

Interesting. The article seems severely dumbed down in places and I'm

not familiar with Fisher information, but the idea sounds neat (and

quite similar to what happens in the Bayesian Confidence Propagation

Neural Networks I'm working with; there the network tries to minimize

an "energy" based on the mutual information and entropy of the

data). I'm not sure it will work out in the end, but it is a fresh way

of looking at things.

Shades of Egan's _Distress_? :-)

I have not found that much of his articles on the net, but one is

available at:

http://xxx.lanl.gov/abs/gr-qc/9703051

Fisher's arrow of `time' in cosmological coherent phase space

Authors: B. Roy Frieden, H.C. Rosu

Comments: 10 pages, LaTex, Honorable Mention at GRF-1997

Journal-ref: Mod.Phys.Lett. A13 (1998) 39-46

Fisher's arrow of `time' in a cosmological phase space defined as in

quantum optics (i.e., whose points are coherent states) is introduced

as follows. Assuming that the phase space evolution of the universe

starts from an initial squeezed cosmological state towards a final

thermal one, a Fokker-Planck equation for the time-dependent,

cosmological Q phase space probability distribution can be written

down. Next, using some recent results in the literature, we derive an

information arrow of time for the Fisher phase space cosmological

entropy based on the Q function. We also mention the application of

Fisher's arrow of time to stochastic inflation models

Here is something from the Optical Sciences Center own pages

(http://www.optics.arizona.edu/News/Oscillations.asp/July.htm):

Fisher Information. A New Concept for Physics

In early April, the Center hosted the first international meeting of

scientists who work with Fisher information in application to

physics. Professor B. Roy Frieden, who founded the group, said the

goal of the meeting was to promote research on the connection between

Fisher information and basic physics.

The charter members of the Fisher Information Interest Group are

(standing) Optical Sciences Center Professors Arvind Marathay and

B. Roy Frieden with Bernard Soffer of Hughes, Malibu and (seated) Roy

Hughes of DoD, Australia. Many members of the group believe that all

of thermodynamics can be derived from the standpoint of minimum Fisher

information. Roy and his colleagues will be seriously attacking this

problem in the fall when another group member, Professor Angelo

Plastino of the Department of Physics of the University of La Plata in

Argentina, visits the Center. He will also work with Roy on Fisher

temperature-and time concepts.

Fisher information is an old concept. It has been used since about

1922 to judge the quality of statistical estimates. Now it is the

central concept in a new theory of measurement. This predicts that

each physical phenomenon arises in response to a request for data

about it. Roy explained, "The probe particle that initiates a

measurement perturbs the measured particle's wave function. This

perturbs the particle's Fisher information level, and initiates a

variational principle whose solution and output is the probability law

that produces the requested measurement. For example, the Schroedinger

wave equation arises out of a request for the position of a

particle. In this way, the phenomenon that is to be measured is

produced `on the spot.' The result is a kind of local creation of

reality. This appears to be an effect that is new to both physics and

metaphysics, resembling the 'participatory universe' of Professor

J.A. Wheeler."

Roy continued, "Virtually all of known physics, from relativistic

quantum mechanics to statistical mechanics to quantum gravity, has

been derived by this measurement approach. The local creation of

reality is a microscopic effect. It arises in measuring and

interacting with single elementary particles. It's reminiscent of the

microscopic reversibility to time of the laws of physics. As with the

latter, we don't yet know how and if `reality on demand' translates

into a macroscopic effect."

A traditional measure of disorder, entropy, has provided the usual

definitions of time and temperature. Said Roy, "Fisher information

provides us with new definitions. They arise out of a newly discovered

`H-theorem' for the information: It can only decrease with time. This

makes Fisher information a measure of disorder and means that Fisher

information must provide its own definitions of time and

temperature. Time is defined to increase when Fisher information

decreases. Intriguingly, we find that Fisher time and entropy time do

not agree about 1% `of the time.' Temperature is defined as the

resistance to a change in energy of the Fisher information of a

system. The relationship of the Fisher temperature scale to the

entropic, or conventional, temperature scale is currently not known."

B. Roy Frieden's fall 1998 course offering, Opti 529, crosslisted as

Phys 529, is titled "Physics from Fisher Information, a Unification."

It will show that Fisher information provides a basis for nearly all

physical laws, including quantum mechanics, classical e&m theory,

special and general relativity, diffraction optics, the statistical

gas laws, quantum gravity, and the ubiquitous 1/f-noise power law. The

textbook for the course, Physics from Fisher Information, a

Unification by B. Roy Frieden will be published in December 1998 by

Cambridge University Press.

B. Roy Frieden has been with the Center since 1966 and has worked with

Fisher information since 1987. His research interests include digital

methods of enhancing or restoring images, blind deconvolution, and the

synthesis of physics using Fisher information.

-- ----------------------------------------------------------------------- Anders Sandberg Towards Ascension! asa@nada.kth.se http://www.nada.kth.se/~asa/ GCS/M/S/O d++ -p+ c++++ !l u+ e++ m++ s+/+ n--- h+/* f+ g+ w++ t+ r+ !yReceived on Thu Feb 11 04:52:17 1999

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