Hi Ines,
Consider the evolution of the system with 4 initial distinguishable states A,B,C and D to 2 orthogonal states 0 and 1, with A evolving to 0, and B,C,D evolving to 1. There is a clearly a reduction in the physical entropy of this system and an observer with access to observe this evolution might decide to associate the AND operation with this evolution. We will call this a faithful physical realization of the AND operation in a system.
Now consider the evolution of the system with 4 initial distinguishable states A,B,C and D to 4 orthogonal end states 0, 1,2 and 3 with a one-to-one evolution. There is no reduction in the physical entropy of this system and another observer with access might decide to associate the physical state 0 with the logical state '0' and the physical states 1,2 and 3 with the logical state '1'. Such an observer will associate the AND operation with this evolution (this is the principle of reversible computing where there is no minimum dissipation) and will not be wrong. The difference being that this is what we refer to as an unfaithful physical realization of the AND operation.
I was trying to point out that it is possible to associate interesting computation with a system evolution in which there is no change in the physical entropy of the system. There might be reduction in the entropy of the observer, not sure there has to be though. Perhaps I am missing/misunderstood something? Are you saying that the reduction in the entropy of the observer (and not necessarily the system) is enough to imbue the system with a goal? I was contesting the idea that entropy reduction in the system alone is enough to achieve that.
Yes, the equations that I have obtained are themselves well established in the Information Bottleneck method (used in clustering and machine learning) and my main contribution is tying it all together in a physical sense. I was pointing out the criticality part, since it seemed the idea though popular is still debated as there seemed to be no clear theoretical foundation for why the brain needs to be a critical system. Most criticality arguments are made from observing neuronal avalanches on EEGs and other experimental data, which can be explained away using critical behavior. And calculations of expected branching parameters is much lower than what is seen in the critical brain. Being able to view different cognition states as phase transition in input signal mapping can allow us to bypass these past hurdles I think. But I have to give it much more thought.
And please call me Natesh. Ganesh is my father. We have a whole different first name, last name system.
Cheers
Natesh