Dear colleagues,
I have two comments on the recent discussion.
Michael Devereux made a good point:
"I'm sure, as you say, Andrei, that we must definitively specify
information by a precise mathematical formulation, if we expect to make
any progress. But, I think the Shannon and von Neumann formulas are not
sufficiently general. They only describe the information content of an
ensemble of identically prepared objects. That's entirely adequate for
the statistical results of real quantum experiments, or, say, for the
train of electrical pulses in a telegraph signal, but they do not
describe an individual bit of information. "
I think in this context it is also good, as John Collier did, to recall
alternative approaches, including Barwise and Seligman, Kolomogorov and
Chaitin, Ingarden et al. Jim Johnson refers to Michael Leyton, who
relates information to causal explanation.All of these theories of
information give interesting and relevant representations in the same
way as ordinary light, x-ray, gamma-ray, infrared, radio waves...will
give you different views of the same object -- lets say a galaxy. All of
them might be necessary for our understanding. It is not the question
"which is the right one?" but rather "what are they good for?".
Just for the sake of completeness, let me mention Fisher information
that also is quantitatively defined, and is epistemologically oriented.
B. Roy Frieden relates Fisher information and focuses on getting
information from the "world" through an interaction (via probe particle)
-- a process that can be seen as a measurement. Measurements are
generally imperfect. What is interesting in this approach is that
Frieden uses Fisher information as a basis for unification of sciences.
See: http://www.optics.arizona.edu/Frieden/Fisher_Information.htm
http://www.powells.com/cgi-bin/biblio?inkey=17-0521810795-0
For me, the most appealing with concept of information in general is its
universality -- it connects virtually completely unrelated phenomena and
research traditions.
The second thing I want to comment on is QM vs. CM discussion where the
possibility to describe usual macroscopic phenomena in QM language was
mentioned. That might also be the way to relate to different concepts of
information.
Could that be so that as long as our knowledge (based on information)
about a system is limited (we know that something is in either of n
states with certain probabilities) some kind of QM description might be
appropriate. As soon as enough information about the "everyday behavior"
of quantum objects will be collected a "classical" description of
quantum landscape will emerge and we will, one way or the other, be able
to talk about particular events with particular objects, not only about
statistical properties of ensembles. For what nanotechnology aims at (if
I got it right) is manipulating subatomic objects. To my understanding,
in much the same way as the STM (scanning tunneling microscope)
visualizes subatomic objects; techniques must be possible to develop to
translate between quantum and classical representations - both ways.
Best regards,
Gordana
________________________________________________
Gordana Dodig-Crnkovic
Senior Lecturer
M�lardalen University,
Department of Computer Science and Electronics
E-mail: gordana.dodig-crnkovic@mdh.se
http://www.idt.mdh.se/personal/gdc/
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Received on Mon Jun 12 08:37:12 2006
