Statistical mechanical perturbation theory dynamics

I now consider statement 3 How should an extension of dynamics be understood In the MPC theory the problem does not exist For the intrinsically stochastic systems there is no need for modifying the laws of dynamics. As for the LPS theory, one notes the presence of two essentially new concepts. The introduction of non-Hilbert functional spaces only concerns the definition of the states of the dynamical system, and not at all the law governing their evolution. It is an important precision introduced in statistical mechanics. The extension of dynamics thus only appears in the operation of regularization of the resonances. This step is also the one that is most difficult to justify rigorously it is related to the (practical) necessity to use perturbation calculus (see Appendix). 

Since the energetic interactions between polymer segments are very similar to those between small molecules, the statistical mechanics of a polymer surface is rather similar to that of small-molecule liquids. The role of connectivity is minor and a theory of polymer surface tension can be constructed in the spirit of van der Waals, which is rather successful at predicting the observed surface tension of polymer melts. This is at first sight slightly surprising, for it must be the case that the presence of a surface imposes a serious perturbation on the conformation of a nearby chain. Both the theory of these conformational effects and experiments to measure them are in a rather rudimentary state, but we discuss what is known, together with the even more uncertain area of the effect of surfaces on polymer dynamics. 

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