[FOM] constructivism and physics (reply to Gordeew)

[joeshipman@aol.com]

Lew, how do you know that the "solution" achieved in "natural reality" 
is really optimal?  Might it not just be optimal among the solutions 
that can arise from a long string folding, while there are lower-energy 
solutions which cannot be reached by a feasible "path" starting from a 
straightened string?

-- JS

-----Original Message-----
From: Lew Gordeew <legor at gmx.de>
...

It might not necessarily be related to physics, but let me remind this
empirical phenomenon.

Protein folding problem:
Given a stable protein as a long string over 20 amino acids identify its
unique 3D spatial structure with minimal energy.

This (obviously constructive) open problem in biology is NP-hard under 
most
mathematical models, and yet in "natural reality" it takes only a few
seconds to achieve the solution. Nobody knows how this is done in 
nature, so
people are testing genetic algorithms to approximate the natural folding
procedure.