Re: [asa] another physics question-information

From: D. F. Siemens, Jr. <>
Date: Tue Oct 30 2007 - 19:36:26 EDT

There is another problem with the conservation of information, or perhaps
a different way to understand a point you make. If a genome is exactly
duplicated, whether in a second cell or second organism, there is no
increase in the amount of information. This holds also when, by
duplication within a cell, a trimer or tetramer results. But the latter
allows a mutation in one part of the genome that increases the amount of
information. There is more information even though the result has no
phenotypic effect. This holds even though there is no more information in
a thousand copies of a document than in one.
t'other Dave (ASA)

On Tue, 30 Oct 2007 18:27:55 -0400 "Randy Isaac" <>
> Dave,
> As is often the case, this topic gets a little clearer if we
> define some
> terms and concepts. The term "information" is used in many different
> ways.
> We usually think of loss of information as the inability to
> ascertain the
> meaning of an intended communication. If static drowns out a
> telephone
> conversation, we think we lost the information. But the concept of
> conservation of information doesn't work quite that way. Information
> may get
> scrambled and unintelligible but it isn't lost. It's just converted
> into a
> form which we can't decipher. The concern that Hawking had over the
> years
> was the absolute loss of information, not just the scrambling that
> makes it
> hard to decode. That debate isn't over yet and for those of you
> interested
> in this topic, here are a couple of articles with a little more
> clarity.
> Note also that in this context "information" is not the
> communication of
> a sentient being. Rather, entropy is the measurement of the
> information
> content. The two types of information are not necessarily totally
> independent of each other but the concepts are quite different.
> Relating this to DNA, there simply is no way that the
> conservation of
> information principle has anything to do with constraining the
> possible
> changes of DNA code. For one thing, energy is expended in the
> process of
> cell replication so it doesn't violate the second law of
> thermodynamics,
> which is essentially the same thing in this context. The entropy or
> information content of cellular DNA can increase or decrease without
> any
> violation of a conservation law.
> Randy

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Received on Tue Oct 30 19:40:17 2007

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