[on the ButterflyEffect, copied here from TheTippingPoint page:]
The reason that the butterfly phenomena works is that the system in question is complex, with each element interacting with each other element in complex (nonlinear ways) so even slightly different initial conditions (this would be a snapshot of a particular moment) can result in very different results.
So one set of initial conditions has the butterfly with it's wings closed, no storm. Another, completely identical set of conditions, except that the butterflies wings are open results in a storm.
Because the only conditions that are different are the state of the butterflies wings, you might argue that the flap "caused" the storm.
The first difficulty with this explanation is that the system is so interdependent that it is impossible to prove anything effects anything else.
The second difficulty is that in order to prove that the wing flap caused the storm, you have to start out with absolutely the same initial conditions down to the infinite decimal place and do the calculation exactly (no rounding errors allowed).
Why? Because even slight changes can propagate to big differences. So any rounding error or difference in initial conditions can cause very different results, which would make it impossible to assign causation.
In the end, even if everything were done exactly there is a phenomena that guarantees you can't prove causation. Quantum fluctuation. In the initial conditions, there is a photon heading toward an atom. There is a probability that the photon will be absorbed, and one that it will not. As the system evolves, the effect of absorption versus non-absorption can spread. Enough of these events and the difference is felt.
In other words, even if the butterfly did not flap it's wings it still might storm, depending on the roll of a set of million-sided dice.
In other words the butterfly phenomenon is just a bad popularization. -- ThaddeusOlczyk
That just makes the state of the wings one cause among many others.
The idea that the flapping of a single butterfly's wings has large-scale consequences doesn't make much energetic sense. Such a small change can only have large-scale consequences if the global system is in an energetic minimum smaller than the energy of the butterfly's wings, that is to say, if the global system is in an energetically extremely unstable state, however, this can only be a very transitory moment. The chances that the butterfly's wings will flap at such a moment are vanishingly small. Maybe the butterfly-caused storm is just a BadAnalogy? set up to look spectacular in order to sell books. -- AndyPierce
Note that a chaotic system is in an extremely unstable state all the time, in fact, this is almost by definition true. The system will not remain long in this unstable state, but it will proceed to some other unstable state.
See also http://turb20.seas.ucla.edu/~schuang/lorenz.html
-- StephanHoubenSee ChaosToOrder
DaveOlson's book applying ChaosTheory and CatastropheTheory to SoftwareDevelopment: ExploitingChaos - ISBN 0442011121 .