The "Strage loop" phenomenon occurs whenver, by moving upwards (or downards) through the levels of some hierarchical system, we unexpectedly find ourselves right back where we started. They form "tangled hierarchies" (aka heterarchies/Tangled hierarchy)
good explanation on page 691
Strange loops in molecular genetics and number theory
One of the more interesting similarities between the two sides of the map is the way in which "loops" of arbitrary complexity arise on the top level of both: on the left, proteins which act on proteins which act on proteins and so on, ad infinitum; and on the right, statements about statements about statements of meta-TNT and so on, ad infinitum. These are like heterarchies, which we discussed in Chapter V, where a sufficiently complex substratum allows high-level Strange Loops to occur and to cycle around, totally sealed off from lower levels. We will explore this idea in greater detail in Chapter XX.
Incidentally, you may be wondering about this question: "What, according to the Central Dogmap, is Godel's Incompleteness Theorem itself mapped onto?" This is a good question to think about before reading ahead.
He also makes an analogy with record-players, as found in the Contracrostipunctus story.
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Statements in N, and statements in meta-TNT, are both written in English, I suppose, which I guess imitates the complexity in function/meaning of possible proteins (or polypetides), similar to that of English sentences (or polywords).
Proteins act on DNA to produce new DNA, just like meta-TNT statements can give new TNT statements.. Though this is only approximate, the analogy is between TNT's self-ref, and DNA's self-rep..
Comparison with Feedback
On page 545 of GEB.
The difference is that feedback transmits any signal around a loop, while strange loops transmit more complex information.. It's not an unambiguous definition though..
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Note that proteins acting on proteins, to be analogous to how TNT works, should refer to proteins that act on DNA, which codes for proteins. This kind of regulation indeed happens all the time, and gives rise to Gene regulatory networks!
Strange loops (Chap XX)
See his nice chess example in next page
Things must follow *some* rules at a level low enough, it must bottom-out. However, on top you can have a tangled-hierarchy which creates much complexity.
See good explanation on page 691
