[time 249] Fisher Information physics...

Stephen P. King (stephenk1@home.com)
Sun, 18 Apr 1999 21:27:56 -0400

Hi Guys,

This may be of interest,

from: http://www.optics.arizona.edu/News/Oscillations/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.

        Roy continued, "Virtually all of known physics, from relativistic
quantum mechanics to statistica1l
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."

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