(Vyv Huddy 26/11/2015; 13.57)
Dear All,
I noticed a reference to control in an old book by Sagan and Shklovskii "Intelligent Life in the Universe". This cites a Soviet mathematician call Liapunov (actually Lyapunov) who seems to have put forward a few points that might (or might not) resemble PCT (particularly p. 199). I thought it might interest a few of you.
Apologies for the quality of the scan I used an iPhone app. It is from a chapter titled "definition of life" and the preceding section is fairly mundane biology so I didn't include it.
All the Best
Vyv
Sagan Shklovskii .pdf (4.28 MB)
ATT000011.txt (56 Bytes)
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-----Original Message-----
From: Huddy, Vyv
Sent: 25 November 2015 20:51
To: Huddy, Vyv
Subject: [Scan] Sagan Shklovskii
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[Martin Taylor 2015.12.06.14.07]
(Vyv Huddy 26/11/2015; 13.57)
Dear All,
I noticed a reference to control in an old book by Sagan and Shklovskii "Intelligent Life in the Universe". This cites a Soviet mathematician call Liapunov (actually Lyapunov) who seems to have put forward a few points that might (or might not) resemble PCT (particularly p. 199). I thought it might interest a few of you.
Apologies for the quality of the scan I used an iPhone app. It is from a chapter titled "definition of life" and the preceding section is fairly mundane biology so I didn't include it.
This is very interesting. Could you scan or post the Lyapunov reference? He is saying exactly what I was talking about on CSGnet maybe 20 years ago when I was saying that a control system is a refrigerator, in that it keeps the entropy of the controlled variables lower than they would be if the organism was subjected to unconstrained influences from outside, and in my Editorial introduction to the PCT special issue of the International Journal of Human-Computer Studies.
It's interesting that it should be Lyapunov they reference, since he is best known for the "Lyapunov exponent" of chaotic systems. It expresses the rate of divergence of the orbits in a dynamic. Taking the logarithm makes an exponential divergence become a linear one, and that is easily interpreted as a linear rate of entropic increase -- or equivalently of information loss. So his interest in chaotic dynamics feeds very naturally into the considerations described in the extract you scanned. The "refrigeration" created by control is the supply of information that compensates for the divergence supplied by the disturbance. Very interesting.
Martin
[Vyv Huddy; 12.12.2015;1256gmt]
Hi Martin,
MT: This is very interesting. Could you scan or post the Lyapunov reference?
VH: I'm afraid the Sagan / Shklovskii book does not have a reference for Lypunov ... it is very poorly referenced in general - cybernetics isn't even mentioned in the subject index. Surfing the net has turned up nothing yet but if I find something I'll post it here. I've attached the cover of the book. Incidentally the book a great read ... though out of date and highly speculative ... at one point even suggesting at one point that the Martian moon Phobos might be an artificial satellite (!) on account of its [at that time] increasing orbital velocity. I expect subsequent observations have disproved this....
MT: He is saying exactly what I was talking about on CSGnet maybe 20 years ago when I was saying that a control system is a refrigerator, in that it keeps the entropy of the controlled variables lower than they would be if the organism was subjected to unconstrained influences from outside, and in my Editorial introduction to the PCT special issue of the International Journal of Human-Computer Studies.
VH: Phil Runkel included one paragraph in CNTS that mentions entropy (p. 76). I was looking for similar so your paper is very helpful - thanks.
MT: It's interesting that it should be Lyapunov they reference, since he is best known for the "Lyapunov exponent" of chaotic systems. It expresses the rate of divergence of the orbits in a dynamic. Taking the logarithm makes an exponential divergence become a linear one, and that is easily interpreted as a linear rate of entropic increase -- or equivalently of information loss. So his interest in chaotic dynamics feeds very naturally into the considerations described in the extract you scanned.
VH: Slightly out of my depth here ... my knowledge of mathematics is lagging way behind my enthusiasm here I'm afraid.
MT: The "refrigeration" created by control is the supply of information that compensates for the divergence supplied by the disturbance. Very interesting.
VH: I'm not clear what you mean by information here?
VH: Thanks Martin for your interest!
Martin
