The Lord and the reptationist Apostles
Pierre Gilles de Gennes
photo borrowed from espci.fr web site)
This is not the title of a Fable from Jean de La Fontaine, it is a true story of the grandeur of a giant in science, de Gennes, and of the more questionable conduct of some of his followers, the reptationist believers. It is the celebration of Greatness and the denunciation of Smallness, a classic, as long as humanity will last. It could, actually, be the topic for a new fable.
Once upon a time in 2006, just before he died, Pierre Gilles de Gennes, the Renaissance scientist of our modern times often compared to Newton, was asked to be a jury member for the PhD qualification of Hakima Mendil[1], a student of Laurence Noirez, famous for her experimental work in micron-thin sample rheology studied under Rheo-SANS conditions (see my previous blog and below). Noirez had found many instances where the established concepts of considering polymeric melts as true liquids at vanishing stresses clearly failed and she had her student focus in her thesis on those problematic areas of the liquid viscous state, especially exploring the unspoken inability of the reptation model to explain those results. The reptation model[2] was coined by de Gennes himself, some 40 years earlier, contributing to his Nobel celebrated fame.
I am not sure that Newton would have accepted to serve as President of a thesis denying his theory of gravitation, but de Gennes accepted, along with another eminent reptation theorist[3], G. Marrucci from the University of Naples, another Seigneur, and along with them some other known loyal and fervent apostles of the reptation faith, known for serving as reviewers for the most prestigious polymer journals. Imagine the courage of Mendil to have to expose her controversial findings in front of such a prestigious panel!
Mendil’s thesis is one of the kind: it is well written, the ideas and concepts are well exposed, the experimental set up well explained, in one word it is brilliant! True, Mendil’s results and conclusions are enlightening the great challenges facing the existing models of polymer melt deformation:
If the concept of reptation is essential to the description of the role of entanglements, it is not sufficient to exhaustively describe the dynamics of the chains. Other mechanisms ("Contour Length Fluctuation" (CLF), "Convective Constraint Release" (CCR)) had to be added and have contributed to a better description of the experimental results. Despite the considerable advances made, it appears necessary to improve the description of the rheological behavior of entangled linear polymers, because the interpretation of mere simple behavior, such as “shear-thinning”, has not yet received a real consensus. Has an essential mechanism of the global description of polymer dynamics been missing? To what extent can rheology fully reflect the dynamics of the chains in polymers?
In our days, the rimes, the cartoons and other metaphors to express derision or criticism are no Panzer divisions against intolerance. Dictatorship rules, hidden or in the open. This was sadly recently illustrated in the “JE SUIS CHARLIE” murders in France, Denmark and Tunisia. Those who believe to hold the truth do not accept contradiction, controversy: no debate, suppress the evidence, just assassinate!
Unfortunately, this intolerance also prevails in science. No Kalashnikov, of course, there are other subtle weapons to exercise fundamentalism: censorship, deny or delay publication, prevent the award of grants to finance the research, invite the infidels to present their work as posters on the last day of the conference, when most of the attendees have left. This unacceptable intolerance was told in Chapter 1 of the book by Lee Smolin (see the picture at the bottom of this blog) “Trouble in Physics” who explained the Smallness and the Meanness of those holding the decision and had the power, in his field of theoretical physics, and prevented the emergence of new ideas in quantum gravity against the dominant “String model”.
The same is true in polymer physics. The reptationist apostles have been placed at the top of the reviewing boards, slashing and blocking from publication everything work that might contradict their faith and denying grant allocations to the corresponding research. I have too many cruel examples to quote, many from the reviewers of Mendil and Noirez’s publication attempts (which have been systematically delayed or denied publication in high visibility journals, such as PRL, Rheological Acta, Europhys. Lett., Soft Matter, J. of Rheology etc.).
Contrast this Smallness with de Gennes’ Grandeur, his impeccable scientific attitude against censorship of a work exposing the challenging deficiencies of his accepted theory: not only was Hakima Mendil granted her PhD with High Honors, but, under the recommendations of de Gennes himself, she became the laureate of the prestigious Prix Joliot Curie awarded by the University of Paris for best doctoral research that year!
Mind you, I am not declaring that de Gennes is our Mandela of science; he already had his Nobel award, which made easier to profess a Noblesse Oblige approach. Besides, science itself requires fairness, an open mind and the acceptance of opposing views provided they are well supported by experimental evidence or by solid theoretical reasoning. That was the case in Mendil’s thesis and in the publications she tried to publish with co-workers afterward. Prof. de Gennes behaved as he should have: as a true scientist.
The “moral of this Fable”, as La Fontaine would have said, is not that there are some unethical reviewers who abuse their power of censorship, confusing science and religion: there will always be Smallness in this world; what is important is that de Gennes, the great scientist that he was, realized that some fundamental aspect of macromolecular physics was missing in his theory and that these findings should be exposed, taught, revealed, published and explained. This is probably why he suggested the Joliot Curie award to Mendil!
So, if you are intrigued to what controversial results de Gennes would have liked to see published uncensored in the most read publications, a JE SUIS CHARLIE manifestation, here they are, downloadable at your fingertip:
1 H. Mendil’s thesis: H. Mendil's thesis
2. Noirez et al. work on Rheo-SANS : Philosophical Magazine 2011
3. Noirez et al. evidence of solid-like manifestation in polymeric melts: Polymer Inter 2009
and also, more recently:
4. Ibar et al. (accepted for publication in J. Macromol.Sci. Phys., 2015): Dual-Phase Elastic Dissipative sweeping wave
(evidence that the solid-like manifestation is due to the sweeping of the elastic dissipative wave generated by the Dual-Phase structure of the interactions in polymer melts).
5. Ibar J.P. (accepted for publication in J. Macromol. Sci. Phys., 2015): Trouble with polymer physics: Sustained-Orientation
[1] Hakima Mendil, “Identification d'un Comportement Terminal Elastique dans les Fondus de Polymeres, de Polymeres Cristaux Liquides et Analyse de la Transition de Phase Induite par Cisaillement », PhD Thesis, Universite Paris XI, (2006). See the link below.
[2] P.G de Gennes., Scaling Concept in Polymer Physics; Cornell University Press: Ithaca, NY, 1979.
[3] G. Marrucci, & G. Ianniruberto,. “Interchain pressure effect in extensional flows of entangled polymer melts. Macromolecules, 2004, 37, 3934-3942
