From: Denyse O'Leary (oleary@sympatico.ca)
Date: Fri Nov 07 2003 - 16:23:04 EST
> "Re: "Natural processes, over the history of the universe, have the
> potential to produce up to 70 bits of information." This sure seems to
> me to be a remarkable leap from a somewhat arbitrary "let's suppose"
> number used by Behe to develop his argument. Here the number is >
rendered> as established fact.Am I missing something (always possible!)?
> JimA "
Jim Armstrong queried Durston's figures, and this is his response
With regard to a reasonable upper limit for the amount of information
that natural processes could be expected to generate, here is a
clarification of my thinking.
First, I am defining functional information as the difference in Shannon
entropy between a physical system that has no constraints placed upon
it, and a physical system that has been constrained to perform a
specified function.
For a maximum upper limit, we can refer to two recent papers. One by
Lloyd, S. (2002). Computational capacity of the universe. Phys. Rev.
Lett. 88, no. 23, 237901-1 to 237901-4. Doi:
10.1103/PhysRevLett.88.237901, and the other
paper by Bekenstein, J. (2003). Information in the holographic universe.
Scientific American. August issue. From these two papers, we can
calculate the maximum amount of functional information that could be
produced by the entire universe. The value we get from Lloyd's paper is
about 400 bits, from Bekenstein's paper, 409 bits. Both of these
computations assume a capacity that far exceeds what much slower,
chemical processes involved in organic life are capable of. For example,
Lloyd's paper assumes that the universe is a quantum computer operating
over 10 byrs. Chemical processes do not cycle at quantum speeds, so the
amount of information chemical processes could generate would be far
less than 400 bits.
For the next step, we note that functional Shannon information has, at
it's core, a ratio which represents the number of functional
configurations (Nf) vs. the total number of configurations possible,
both functional and non-functional (N). A certain amount of functional
information can be produced from scratch, in theory, in nature through
what is known as a 'random walk'. The probability (Pf) of 'finding' a
functional sequence or configuration that has a ratio of Nf/N is equal
to Pf = (Nf/N)(R!/R^R) for a random walk. We can use this equation to
calculate the number of trials or steps that we could expect to undergo
before achieving a certain level of information. For example, a
functional string of binary code that contained 70 bits of functional
information would require approximately 1048 trials to 'find' via a
random walk. Observing events in nature that have a probability of
10^-48 is so unlikely that we could hypothesize that such an event will
never likely be observed with any reasonable expectation. For proteins
that are not well conserved, say, with a functional information content
of .46 bits per amino acid, achieving 58 bits of information would take
roughly 1072 steps in a random walk. Keep in mind that since most of
protein sequence space is non-folding, natural selection cannot guide
the evolutionary trajectory. Thus, it becomes a random walk as it
evolves through non-folding sequence space. The bottom line is that
somewhere we need to choose an upper limit for the amount of information
natural processes can generate. Depending upon the 'alphabet' used (e.g.
binary, or 20 amino acids, or 4 bases) that upper limit will vary. The
hypothesis I work under is that the upper limit will be somewhere around
70 bits, due to the number of steps required to achieve that level of
information via a random walk, the time constraints we have within
nature, and the amount of material and energy required for larger jumps
in functional information.
This hypothesis yields two falsifiable predictions: a) natural processes
will never be observed to produce more than 70 bits of information, and
b) any configuration or sequence that is actually observed to be
produced that contains more than 70 bits, will always be produced by an
intelligent agent.
Thus far, there are no cases where either of these two predictions have
been empirically falsified.
Having said all the above, I believe that 70 bits is too conservative,
and the upper limit is closer to 40 - 45 bits. In a recent computer
simulation (Lenski et al., (2003). The evolutionary origin of complex
featuresı Nature 423, 139-144.) an information jump of 32 bits could not
be achieved (although I believe that in theory it can be achieved). Only
when intermediate stepping stones were introduced into the virtual
fitness landscape, could the simulation achieve a 32 bit function. Of
course, this was achieved by inputting the information into the virtual
fitness landscape in advance, permitting much smaller information jumps;
this is a significant 'cheat'. When those intermediate steps were
removed, the simulation failed to achieve the 32 bit function. In
reality, we do not have advance information input into the natural
fitness landscape and if we did, then we would have to account for where
this information came from. For example, when it comes to the generation
of novel protein folds, the sequence space between islands of folding
sequence space is non-folding, hence non-functional, hence no effect on
the phenotype (assuming the evolving gene is a duplicate and, hence,
expendable). If there is no effect on the phenotype, natural selection
cannot influence the evolutionary trajectory of the evolving
protein-coding gene between the islands of stable folding sequence
space. Finally, the islands of stable, folding sequence space are
usually much more than 70 bits removed from each other.
Bottom line: the 70 bit upper limit is an hypothesis that makes
falsifiable predictions that, thus far, are still standing.
Kirk
-- To see what's new in faith and science issues, go to www.designorchance.com My next book, By Design or By Chance?: The Growing Controversy Over the Origin of Life in the Universe (Castle Quay Books, Oakville) will be published Spring 2004.To order, call Castle Quay, 1-800-265-6397, fax 519-748-9835, or visit www.afcanada.com (CDN $19.95 or US$14.95).
Denyse O'Leary 14 Latimer Avenue Toronto, Ontario, CANADA M5N 2L8 Tel: 416 485-2392/Fax: 416 485-9665 oleary@sympatico.ca www.denyseoleary.com
This archive was generated by hypermail 2.1.4 : Fri Nov 07 2003 - 16:20:14 EST