Chemical Engineering Science 55 (2000) 2749}2765 Danckwerts Memorial Lecture The art of mixing with an admixture of art: viewing creativity through P. V. Danckwerts's early work J. M. Ottino* Department of Chemical Engineering, R.R. McCormick School of Engineering and Applied Science, Northwestern University, Evanston, IL 60208-3120, USA Dedicated to the memory of my father Abstract P. V. Danckwerts's work provides a springboard for an examination of issues dealing with creativity in research and acceptance of new viewpoints. When is a concept ready to be embraced and to what extent can an advance be premature? I argue that the visual arts o!er thought-provoking analogies and examples are used to illustrate various points. ( 2000 Elsevier Science Ltd. All rights reserved. 1. PVD:s oeuvre and objectives of this work PVD had already written some of the most in#uential papers before I was in my teens and was still at it PVD+s work provides a springboard for a discussion when I wrote my "rst paper in Chemical Engineering about creativity. Science. My research connections and indebtedness, The Danckwerts Memorial Lecture provides an op- however, are too obvious to miss. In Insights PDV broke portunity to look at the past and project into the future. his research output into four sections, including one It is honor to be invited to attempt to do this. The key that he called RTD and Related Topics, and another, issue is: In what possible ways may I provide some Mixtures and Mixing, covering mixing measures and the illuminating viewpoint? like. I tend to view these two areas as brackets: The It would be foolish to attempt to place P. V. Dank- RTD concept succinctly capturing in one stroke the bare werts's (PVD's) oeuvre in perspective. This was done by elements of the process (and often the only thing one Neal Amundson, the "rst Danckwerts's Lecturer, in 1986 needs to know), the quanti"cation of mixing, on the (Amundson, 1986), by PVD himself in his `Insights into other, forming a separate chapter that is far from being Chemical Engineeringa (Danckwerts, 1981), and by closed. Rutherford Aris in 1990 in both, a pithy review of PVD's I will use this opportunity for an examination of Insights as well as in his own Danckwerts Memorial issues dealing with creativity in research and acceptance Lecture in 1991. of new viewpoints, using the mixing theme to anchor a few concepts. When is a concept ready to be embraced *E-mail address: [email protected] (J. M. Ottino). and to what extent can an advance be premature? Note to the Reader: The fact that someone may do work that may The example of Osborne Reynolds (1842}1912) * be regarded as creative does not mean that one should be aware of the foreshadowing chaos before the work of PoincareH formed process of creativity itself. I have been, however, seriously interested in part of the accepted mathematical vocabulary * visual arts, and to a lesser extent, in general aspects of creative pro- cesses, for far longer than I have been doing chemical engineering. To provides a striking example. Two examples from my own paraphrase PVD, the title of this presentation is somewhat pretentious, work * chaotic mixing of #uids and the self-organiza- but a title was needed, and I hope that readers will "nd the ideas tion of segregating granular materials * are used to presented thought-provoking. The research examples are from my own highlight issues having to do with modeling and theory. work; quite certainly they are not the most transparent in illustrating Visual arts analogies are used throughout to illustrate points but are cases whose historical genesis I am most familiar with. The scope of the comparisons between Art/Science is limited in the the various points. The paper concludes with a summary sense that the majority of the parallels presented focus in the time-frame of `lessonsa distilled from the examples presented in 1890}1950. In any case I appreciate the opportunity to air my views here. the work. 0009-2509/00/$- see front matter ( 2000 Elsevier Science Ltd. All rights reserved. PII: S 0 0 0 9 - 2 5 0 9 ( 0 0 ) 0 0 0 1 9 - 1 2750 J. M. Ottino / Chemical Engineering Science 55 (2000) 2749}2765 Fig. 1. Pablo Picasso (Spanish, 1881}1973). Baboon and Young (Vallauris, 1951). The head consists of two toy cars, the ears were ceramic pitcher handles, and the large belly was a large pot. The objects, once combined, cannot be seen independent of the whole. Bronze (cast 1955), after found objects, (53.3;33.3;52.7 cm). The Museum of Modern Art, New York. Mrs. Simon Guggenheim Fund. ( The Museum of Modern Art, New York. ( 2000 Estate of Pablo Picasso/Artists Rights Society (ARS), New York. 2. Creativity views claim to completeness let us consider some of the main issues. De,ning a few terms to provide a setting. Much has been written about creativity and the There are hundreds of books, ranging from the highly creative processes, and there is a considerable body scholarly to the eminently practical, as to what creativity of literature scattered over several intellectual domains is and who possesses it. Opinions range from the German addressing the related topics of invention, creation, philosopher Immanuel Kant (1724}1804), for whom not and discovery. Hamlet was created, the telephone was even Isaac Newton quali"ed as creative * `Science is invented, and the structure of DNA was discovered. ephemeral, art is permanenta, he said * to organiza- Which one is more personal? Many will argue that Artis- tional behavior views, where creativity is supposed tic Creation is: Without Picasso Baboon and Young to be possessed, to a degree or another, by most would not exist (see Fig. 1); on the other hand, the individuals (Amabile, 1996) and where creativity is seen to lie at the intersection of motivation, creative The number of work in this area by chemical engineers is small. ability, and knowledge. What is pertinent here is scienti- Exceptions are the articles of John Prausnitz and Val Haensel (e.g. "c and technological creativity. Without making any Prausnitz, 1986; Haensel, 1994). J. M. Ottino / Chemical Engineering Science 55 (2000) 2749}2765 2751 argument goes, if Thomas Edison had not lived someone new knowledge about the world around usa (Polya, would surely stumbled into the light bulb, and `Newton's 1954a, b). lawsa would have been discovered, probably not by Point (ii) in Simon's list is uncontroversial, though, Newton, but inevitably, though possibly in a di!erent I believe, people tend to overrate the mythical sudden form (think of calculus and Newton and Leibnitz or the #ashes of genius rather than the more mundane aspect of progressively more sophisticated views of mechanics, the value of persistence in creative work. Point (iii), `Lagrangiana (after Lagrange, 1736}1813), `Hamil- however, is less obvious than may appear at "rst glance. toniana (after Hamilton, 1805}1865), and so on). Unques- What does exactly constitute a related "eld? Who in 1950 tionably all this has to do with the issue of uniqueness; would have called di!raction an essential tool in the with the personal stamp of the creator. toolkit of biologists? (think of James Watson and Francis Are creative thinking processes in di!erent disciplines Crick and the discovery of DNA; Watson, 1968). And * art, science, and technology * in di!erent classes? Is what about computer science, which has recently invaded one a more profound act of creativity than the other? molecular biology to the point that molecular biology is Jacob Bronowski'sde"nition is all-embracing: `There regarded by some as a subset of information science? exists a single creative activity, which is displayed alike in Having the right tool at precisely the right time * think the arts and in the sciences2the scientist or the artist of mathematics in chemical engineering in the 1950s or takes two facts or experiences which are separate; he a combination of computer science/molecular biology "nds in them a likeness which had not been seen before, now * allows one to solve problems that may remain and he creates a unity by showing the likeness.a hidden to others. (Bronowski, 1958). His views extend to the uniqueness But creativity is not just about solving problems. It is issue; a scientixc theory can bear the stamp of his creator, about creating them. Einstein supports this view: `the Bronowski opines, and I concur. formulation of a problem is often more essential than its Let us make one more observation contrasting science solution, which may be merely a matter of mathematical and technology. Let us assert that science is explaining or or experimental skill2to raise new questions2requires unveiling * revealing what was already there * whereas creative imagination2a. technology is making and building. It then follows that in Creative ideas involve departing from the canonical science the "nal result is inevitable and that creativity picture, the standard picture of the times. Normal train- enters in the construction of the path leading to the ing in science involves learning the canonical picture, the unveiling of the result. But it would be hard to argue that established techniques accepted in an intellectual do- technology is inevitable. In this case creativity enters in main. Creativity is needed to deviate from normal science both, the product and the path. and create a new paradigm (Kuhn, 1962). The key is to But what about the creative individuals themselves? learn the canon without falling captive to it. Most of the Are there common traits and characteristics? Herbert great names in science posed a big question and solved Simon's views on this issue are particularly clear (Simon, the simplest problems "rst.