Randy wrote
This also leads to an important observation on the
'information' in the genome. Charles Bennett once gently corrected me, saying
that technically, the more accurate term is 'complexity' not 'information.' The
genetic code conveyed from one cell to its replicated cell is not 'information'
as Shannon described. This 'information' is not independent of its physical
embodiment. The physical embodiment IS the information. It is never converted
from one medium to another. This is really complexity, not information. The
supposed notions of conservation of information don't apply to the genetic code.
It is not a message conveyed from one agent to another. Information about the
genome and its sequence of course is classical information.
I have to quibble with this. Evidently this distinction depends on the three points you stated at the beginning of your post:
1. Information is physical
2. Information is independent of its physical
embodiment
3. Erasing one bit of information dissipates at
least kT/2 of energy
However, these points seem to leave out what information _is_: symbols organized in such a way that they convey instructions or data. To say that the genome contains complexity instead of information leaves out (IMO) this characteristic. The genome resembles a computer program that specifies an algorithm for building cellular structures. And that to me is something more specific than complexity.
BTW, in point 3 I presume k is Boltzmann's constant. Is T the temperature? And if so what temperature does it represent? Some latent heat required to record the bit? The ambient temp? ...?
Bill Hamilton
William E. Hamilton, Jr., Ph.D.
248.652.4148 (home) 248.821.8156 (mobile)
"...If God is for us, who is against us?" Rom 8:31
----- Original Message ----
From: Randy Isaac <randyisaac@comcast.net>
To: asa@calvin.edu
Sent: Sunday, April 8, 2007 7:17:50 PM
Subject: [asa] Information and knowledge
Having finally worked my way through the mountain
of posts from the last three weeks, I'd like to comment on a couple. There were
several references to information, its mass and energy, and its relationship to
the genome. Maybe we should remind ourselves of some of the fundamental
principles of information.
Claude Shannon was the key pioneer of information
theory. Rolf Landauer may have done the most to turn it into a bona fide hard
science. Charles Bennett has been a leader in moving Shannon's ideas in the
classical realm to the exotic world of quantum theory.
Landauer made a number of key
observations:
1. Information is physical
2. Information is independent of its physical
embodiment
3. Erasing one bit of information dissipates at
least kT/2 of energy
The first point indicates that without mass or
energy, there is no information. How much mass is there in information? The old
joke is that "my briefcase is so heavy because I downloaded so many books onto
my hard drive." This confuses two types of information--the message or meaning
that is conveyed vs the basic binary bits underlying that information. A 80GB
hard drive contains the same number of bits no matter what is downloaded. They
just aren't all intelligible until we rearrange them.
The second point is easily visualized by thinking
of a telephone conversation. As the information passes from the mind of person A
to the mind of person B, the physical medium that conveys the information
changes many times. The information doesn't.
This also leads to an important observation on the
'information' in the genome. Charles Bennett once gently corrected me, saying
that technically, the more accurate term is 'complexity' not 'information.' The
genetic code conveyed from one cell to its replicated cell is not 'information'
as Shannon described. This 'information' is not independent of its physical
embodiment. The physical embodiment IS the information. It is never converted
from one medium to another. This is really complexity, not information. The
supposed notions of conservation of information don't apply to the genetic code.
It is not a message conveyed from one agent to another. Information about the
genome and its sequence of course is classical information.
Randy
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Received on Mon Apr 9 09:11:53 2007
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