Re: poly: is information the bottom line?

From: Anders Sandberg <>
Date: Thu Feb 11 1999 - 04:50:21 PST

Damien Broderick <> writes:

> Truly mindboggling article about the work of Roy Frieden on Fisher
> information and the basic laws of physics (there's not much abt him on the
> Web), at
> I'd like to see some informed discussion from the mathematics and
> 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:

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

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!                  
GCS/M/S/O d++ -p+ c++++ !l u+ e++ m++ s+/+ n--- h+/* f+ g+ w++ t+ r+ !y
Received on Thu Feb 11 04:52:17 1999

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