A Pleading For Chemistry

Dear Ladies and Gentlemen,

welcome to this public habilitation lecture! Such a lecture, though undeniably public, also has a very private aspect to it. For the lecturer it is a most unique event providing a special opportunity to address a very heterogeneous audience. I've heard some habilitation lectures. I know two roughly distinguishable possibilities. The idea of the traditional habilitation lecture assumes that the public consist of 'students' that get to hear a 'first sample' of a lecture by the newly nominated teacher. The topic needn't necessarily be the lecturer's research but can cover an interesting subject of his or her teaching. This style is of a symbolic character and appeals to me very much. Most frequently the lecturer's own work of research, which kept him busy during the time of habilitation, is being explained in a most comprehensible way. I've been thinking about a way to illustrate my current investigations in a most imaginative and colourful manner ­ were I to decide upon this modern type of habilitation lecture. It could be done, although I must admit I'd have quite some trouble structuring the lecture in such a way that a major part of the audience ­ the one that isn't familiar with organic chemistry ­ wouldn't have to struggle against sleep after fifteen minutes. The advantage to this style, however, is undeniably the telling of what one is most intensely engaged in daily.

The traditional style emphasises rather the teaching than the research. Well, I thought, what am I teaching at the moment? Actually I am an ingrained syntheticist. I produce molecules and also convey how it's being done. Of course I could try to introduce an exciting field of synthetic chemistry. I'm afraid however that this way one aspect might fall short, which is to state, in a really comprehensible way, why this or that synthesis be so interesting. I can hear my colleagues: "Why? That ought to work out! That's your daily diet!" Yes, that is true, too... I could do it.

But there is a third item I would be missing: I have something on my mind, something that, until now, I've only entrusted few persons with. It's not decidedly teaching nor decidedly research. It could be paraphrased as Weltanschauung, though this would be putting the stakes too high. Let's call it Scienceanschauung. Sometimes I am worrying about chemistry as a science. Not that it has lost its fascination to me, on the contrary. But I should like to take this opportunity to utter some thoughts on the science of chemistry, its position among other natural sciences, among all sciences, its significance to society, but especially to the young generation of potential scientists, above all chemists. These were the motives why now I would like to deliver a 'pleading for chemistry'.

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First the bad news. The number of chemistry students has been rapidly decreasing for some time. Not only in Basel, nor merely in Switzerland. In Germany at some places barely half as many immatriculations are being counted than was usual just a few years ago. In the US it's the same, and supposedly in many other industrialised countries. Originally I wanted to show you statistics proving that things seem to be going badly for us at the moment. I was almost going to use the graphs for graduations that are pointing downwards with the years ­ above all in comparison to other natural sciences, especially biology ­ to figure out by means of curve fitting where the supposed interception for the trend might be. In other words, when there will be no more use for our kind because nobody wants to study chemistry anymore. Of course then I'd be an extreme advocatus diaboli, a very cynical one at that. This wouldn't suit me, for basically I am an incorrigible, no, a corrigible optimist. Still, to substantiate that this problem is no invention of mine but a subject that many chemists are currently preoccupied with, I'd like to quote from two articles. The first one was written by the (at the time) president of the American Chemical Society, Professor Ronald Breslow. It was published in Chemical & Engineering News [1], a very widely spread US chemist's magazine.

From the President's message: «The image of chemistry. Where is the unbridled optimism of the past that science was the engine that could move humanity into a golden age? Among most scientists, the optimism is still there and well founded, but much of the non-scientific public has a different view. Chemistry, in particular, has lost some of its glamour in the public eye. Advances in chemistry go unreported in the news, although we do get excellent coverage of every chemical accident. The 'science sections' in the major media ­ national newspapers, magazines, and television news programs ­ feature biology and physics, not chemistry.»

This sounds pretty much like a lamentation. But Mr. Breslow continues on how he would like to solve or at least improve on these problems. For instance he advocates public relations: chemistry exhibitions and chemistry museums, playful beginners' courses for children and youths. He also stresses that we chemists do not sufficiently stand up for our scientific interests in politics.

«Members of Congress commonly tell us that we scientists are remarkably silent about our own interests, compared with the lobbying activities of other professional groups. Chemists cannot afford to be reclusive.»

He furthermore urges us to be open to new developments, to cooperate more intensely with other natural sciences.

«Vigorous new fields are opening, in particular molecular biology and materials science. In the past, the field of biochemistry was often excluded as not being part of 'real' chemistry, and this was a big mistake. College and University chemistry departments must not be tied to past definitions that exclude some of the most exciting new chemical areas.»

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A little more agreeing to public opinion is the article by an editor of the Tages-Anzeiger (a Swiss daily newspaper from Zürich), Dr. Rosmarie Waldner, which appeared in Chimia, a widely spread Swiss chemistry magazine [2]. Title (translated): «The ugly duckling or thoughts about image problems of chemistry.»

«Chemistry is accompanying us through everyday life at each step. Beginning with toothpaste for early morning tooth brushing, proceeding to the boiling of the breakfast egg, the nice colourful tie and sitting on a plastic chair at the office up to the medicine against the sniffles or the remedy against our cat's fleas. But only once a year, during the second week of October, chemistry enters broad public consciousness in a friendly way. The Nobel prize for chemistry then proves that honourable achievements can be acquired by chemistry. Otherwise negative headlines prevail: Poisons in food, air or waters, dangerous side effects of medicaments, not to mention chemical accidents. Although omnipresent in people's lives, hardly another science has as bad a reputation as chemistry. How come?

One reason may be the very unspectacular incorporation in everyday life taken for granted. In the foreground it doesn't deal with fundamental questions of being. Looking up into the unfathomable starry sky at night and the question of the origin of the world obtruding, one certainly doesn't think of chemistry but rather of physics. Also movement, this basic utterance of life and matter, of animals and rocks, is ruled by the laws of physics. The invisible world of molecules is remote and as such cannot be perceived by the senses.

To the unsensual bulkiness with which the subject presents itself adds the language of chemistry. Stuffed with inaccessible technical terms and incomprehensible formulas, it gives chemists an immensely hard time explaining their quest even to other academics, not to mention the general public. Pupils at secondary school are being confronted with chemistry, but rarely in a fascinating way. So they get the impression of being treated to dull matter instead of getting acquainted with essential mechanisms in the world's structure.

There's little incentive to engage in this difficult, dull matter as a student. For years there've been laments about lack of chemistry students in Switzerland. Lately applicants can't even count on the prospect of finding shelter in the industry anymore. Jobs in University research and school teaching are scarce anyway. Whatever should cause young people ­ especially women ­ to engage in this branch of studies? A subject which, apart from its thematic inaccessability, suffers from a negative image?

The negative image not only feeds upon catastrophes like Seveso, Bhopal and Schweizerhalle. It also associates with the words 'artificial' or 'synthetic' that appear unsympathetic to many people. Synthetic fibre, artificial fertiliser, plastic or synthetic vitamin C etc. They suggest the unnatural, hostile to life one rather doesn't want to contact.

And here lies the crux of chemistry's image problem. It gets the blame for its negative, 'stinking' aspects, credits for the positive go to those who [...] exploit it: medicine, agriculture, food industry, textile industry etc. When a new revolutionary medicament appears on the market it's the pharmaceutical industry (though frequently there is a chemical plant involved), it's the MD's that brought progress. [...]

It is obvious that the desired chemicals are not or too little being identified with chemistry. Not only is the world of molecules inaccessible to the public, chemistry as a subject of everyday life is not being recognised.

Chemistry must communicate outwards. Chemistry has a communication problem. Technical terms and boring school lessons are one side of the problem, the other is lack of insight that chemistry is a part of society and thus has the duty to inform. Chemists are very well capable of communicating. But they haven't learned to communicate outwards ­ in any case less than their colleagues from physics.»

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We chemists do not hear these suggestions and reminders for the first time. The calls for more openness and publicity don't perish into nothingness either. Currently chemistry departments of many Universities are undergoing some quite essential restructuring. This creates room for the new, integration of new areas and more communication with the public. I'm convinced that already within the next maybe five years the results of these efforts will show. But I'm afraid that such means will affect the popularity of chemistry as a science only a little, too little for us.

Basically chemistry isn't any duller than physics and no more complicated and stuffed with technical terms than biology. The formula language is rather, I'm almost inclined to say: musical, namely picturesque, graphic, related to form. Compare the chemical language to the language of physics. The latter is much more abstract. Or to the biological Latin terminology. I know a few people who find it easier to pronounce "H-two-oh" than Eleuterozoa. Catastrophes happen in many non-chemical areas, although chemistry admittedly plays its part almost always, it does indeed play a part everywhere. Nevertheless, what Bhopal is to us, is Hiroshima or Chernobyl to the physicist, is BSE ("Blame Somebody Else") to the biologist, is war, impoverishment and recession to the politician and the economist. There's dark sides to all sciences. There's also good and bad teachers who convey their subject, whatever it may be, in a dull boring or an enthusiastic fundamental way. I don't believe that the problem can be explained by chemistry being an incomprehensible and 'stinking' science alone. Just think of fragrances, perfumes. They are also chemical. However, Mrs. Waldner has shortly hinted what to my opinion might be the point of the matter: the fundamental questions of being.

Physics, astronomy and chemistry belong to the oldest of natural sciences. The chemist's theoretical framework is very advanced indeed, so for instance by present means we can predict behaviour and structure of many molecules, substances. We do this on the basis of the mostly correct chemical models weÔve been developing for maybe two centuries or more. Also the arts of analysis and synthesis have advanced especially during the last decades. We have the basic means to produce and characterise almost any arbitrary molecule in a chemical synthetic way, molecules we have thought up in advance, whether they be fantasy or copied from nature. And because we indeed encounter products of chemical research at each step of everyday life, we easily realise that the responsibility of the chemical sciences towards society is a great one. As a matter of fact, we feel most challenged when improvement of any properties of substances that are important to society today, like medicaments, plastics, agricultural products, electronic products, environmental products etc., is at stake. We are expected, as we say ourselves, as is being demanded by other scientific, economic and political authorities, to concentrate on confronting the problems of mankind by all available means. Most of us, I should say, feel concerned and are motivated as soon as they work on problems of generally accepted importance.

For two centuries we have been living in an 'enlightened' world. This has led to more technification, too. Obvious problems of humanity are, superficially seen, of a material nature. Chemistry is a material science, and so we feel called upon to get a grip on matter as precisely and scientifically as possible. We call our chemistry a precise science because we feel very much obliged to the basic requirements for a scientific working method: logic, provability, local and temporal independence of experiments. For that reason speculations and hypotheses appear only marginally. Although they admittedly are important generators and motors to every research, the phase of speculation must be quickly overcome otherwise one would be moving on not strictly scientific, non-objective grounds.

Karl Popper, one of our century's most influential philosophers of science, began to detail the requirements and presuppositions for a scientific procedure as early as the thirties. In his Logic of Scientific Discovery, which over five decades he sought to refine by means of sometimes massively extended editions, he keeps especially reminding scientists to be extremely self-critical and proceed accordingly. Scientific criticalism means to elucidate the difficulties to a problem by trying to falsify all the assumptions and hypotheses of a theory, that is to formulate it in a way which always leaves the possibility to disprove that very theory. We chemists surely take the logician's strict arguments and scientific requests seriously. We've succumbed ourselves to them quite early. We do not seek questions that, as we often say, appear to be 'philosophical' to us. By 'philosophical' we mean most commonly that they might well be interesting and thrilling but, by our means, we'll never find out about them. Answers to such questions bear the danger much dreaded by chemists of never being scientifically provable or disprovable and thus worthless. The seriousness with which we stand by this logic of scientific discovery in combination with the concreteness of contemporary mankind's problems to solve has made serious pragmatists of us chemists. The naive curiosity of a child who asks fundamental questions without an intended connection to concrete problems is not our business anymore. We can hardly afford to ­ I'm being provocative on purpose now ­ research along just like that any more. Younger sciences, especially modern biology, but also physics, I believe, indulge in greater freedom when confronted with not obviously applicable questions. No wonder, for historic reasons the protagonists of the younger sciences are less incriminated, and they radiate it. Apart from the so-called concrete problems, they are capable of conveying philosophically significant insights to society, too. We chemists, I daresay, have a rather autistic feature about us, as it were, when it comes to that. We have an enormously experienced, colourful inner world, we have a fabulous intellectual framework at our disposal which helps us achieve what was formerly utterly impossible, but we have difficulties showing this world of ours to the outside, to other natural scientists, and to society at large... Now we seem to have spun around in a circle ­ oh yes, we must communicate more outwardly. We've had that. .. But perhaps not entirely. For now I'm talking about our inner attitude towards the aforementioned pure fact of missing openness and publicity.

Being so immensely preoccupied with material problems ­, unfortunately a synonym for living in an 'enlightened' society ­, we increasingly neglect the daily care for our mental and spiritual values. This is indicated for instance by the steadily decreasing number of people who accept any religious explanations of being.

To tell it in the words of Friedrich Dürrenmatt (photo: 1949) who in 1953 suggested to Emmenberger the nihilist in The Quarry [3]:

«People of our time do not like to answer the question, 'What do you believe?' It's become bad taste to pose that question. One doesn't like to use big words, people say modestly. And least of all to give a definitive answer ­ as for instance: I believe in God the Father, God the Son, and God the Holy Ghost, as the Christians once answered, proud that they could answer. One likes to be silent today when one is asked ­ like a girl to whom an embarrassing question has been put. Of course, one doesn't quite know either in what one actually does believe. It's by no means nothing. Good God no. One believes in something ­ even though it's quite vague, as if an uncertain fog hung over it all. One believes in something like humanity, Christianity, tolerance, justice, socialism and love for one's neighbors, things that sound a little bit empty. People admit it, too, but they also think the words don't matter. What matters is to live decently and according to one's best conscience. And that they all try to do ­ partly by struggling for it, partly by just drifting.»

 

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Well, around 1953, right in the middle of the post war period, the decay of religious values was very advanced indeed. The sciences increasingly took over the part of delivering explanations of being. Of course they always did, but it became a real mass phenomenon only recently in our technified times. The more we participate in the technified world, the more we feel a lack of answers to questions which for the last time we've freely asked as youths: Who am I? Why do I exist? How did it all begin? What sense does it all make? Are there any alternatives? The more we perceive this, the more important for us is the spiritual nourishment that we expect or hope for from the sciences.

The very same Karl Popper, the strict logician, wrote 1959 in the preface to his first English edition of the Logic of Scientific Discovery [4]:

«I, however, believe that there is at least one philosophical problem in which all thinking men are interested . It is the problem of cosmology: the problem of understanding the world ­ including ourselves, and our knowledge, as part of the world. All science is cosmology, I believe; and for me the interest of philosophy, no less than of science, lies solely in the contributions which it has made to it. For me, at any rate, both philosophy and science would lose all their attraction if they were to give up that pursuit.»

Maybe not everyone shares his opinion. Yet just young people who want to decide on a subject for their studies, but who have yet to gather knowledge or experience from which to obtain a profound insight into certain tangible problems, but who are very open and curious, demand of studies in natural sciences or the humanities to also contribute to answers to the fundamental questions of being. All scientists must be aware of this vital responsibility towards not only ongoing students but our modern unreligious technified society in general. I claim: the better a science can communicate its contribution to answers to fundamental questions of being, the better it fulfils its non-material social task, the greater its acceptance and popularity among the public. Of course it can be overdone. Namely philosophers all too often refrain from contributing to solutions to material problems of society, appearing remote from reality and perhaps due to that don't exactly suffer from overcrowded lecture rooms. But this surely doesn't concern us chemists. We hardly appear to the public as scientists remote from, of all things, material values. And neither do all the other natural scientists.

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Where do we stand with our means today? Where are the frontiers of our chemical research? On the following slide I have tried to picture a fairly rough division of our most important research areas.

Down below you see the domain of synthesis and analysis, the basis that represents our rich experience in manipulating molecules. Essentially it was and still is all about chemical bonds that hold together the atoms in a molecule or metal complex ­ with us organic chemists it's mainly the so-called covalent bonds, with inorganic chemists it's coordinative bonds added, but this traditional difference between organics and inorganics has become obsolete nowadays ­ anyhow, it's about creating or breaking those bonds. This enables us to synthesise and analyse new molecules. From this basis two protuberances have begun to manifest for a few decades that do not feature the strong bonds inside molecules and metal complexes but the weaker interactions that hold responsible for recognition processes among molecules. We also call this molecular recognition. One branch is labelled supramolecular chemistry.

Supramolecules, or 'supermolecules' are conglomerates consisting of single molecules of a different or the same kind. A good example for a supramolecule is perhaps the virus coating of a bacteriophagus. It forms a wonderfully symmetric structure of different single molecules, proteins that is, which under favourable circumstances gather spontaneously.

Yet it has become a habit to us chemists that talking about supramolecules we mean above all artificial systems which, after its components having been created by us chemically-synthetically, gather just as spontaneously. The weak non-covalent interactions that hold together such supramolecules are also responsible for all the processes that keep alive a cell. The second branch deals with the investigation and explanation of structures and reactions that usually take place in water under, let's say, biotic conditions. Biophysical, bioinorganic and bioorganic chemistry ­ obsolete distinctions again ­ lie in the sphere between traditional chemistry and biochemistry; biochemistry in a most generalised sense, consequently everything that has to do with biology on a molecular level: biosynthesis, cellular metabolism, enzymology, molecular biology etc. Most important for chemists is the mutual exchange of insights between the two branches.

Contrary to other natural scientists we chemists live in a world pretty much of our own. It has been created by ourselves. I would like to quote Marcelin Berthelot, an important synthetic-organic chemist of the last century, for his belief still demonstrates our attitude towards our own science in a very poignant way. In 1860 he wrote in one of his monographs [5]:

«Chemistry creates its object. This creative quality, resembling that of art itself, distinguishes it essentially from natural and historical sciences. The latter have an object given in advance and independent of the will and action of the scientist.»

Notice: Berthelot didn't regard chemistry as a natural science. We have our own theories on chemical bonds, molecules, reactivity. We have acquired a time-independent intellectual framework which helps us create almost arbitrary shapes and properties. For centuries we've been creating an enormous variety of molecules, mostly unprecedented substances. You could say that, what the earth is losing in biodiversity everyday, the chemist 'compensates' with molecular diversity. I admit, even I register a certain amount of satisfaction about this selfgenerated creativity ­ but only for short. For soon this unpleasant feeling obtrudes that it is probably high time to extend our view. The fact that we pursue a self creating art of science results from the history of chemistry. We have thus acquired a rich treasure of experience and manipulation that we want to apply wisely. Yet it is getting obvious that we will have to increasingly compound with other research areas. With solid state physics and other materials sciences, with electronics, biology, medicine, pharmacy, with areas like hydrodynamics, population dynamics, quantum dynamics. In simpler terms: it's interdisciplinary research for us, now... I'm running in open doors again, some of you will say. That's just what we've shown consideration to for several years or even decades! We teach ourselves and our students many subsidiary subjects. We continually emphasise the importance of interdisciplinary research. We like to collaborate with colleagues from other areas, this has almost become the norm! Year after year publications are being edited that demonstrate the highly interesting results of interdisciplinary research.

I believe: it takes more. What we often do when we work interdisciplinarily is to deal with the working methods of the other areas. What we chemists rather miss is to integrate the theories of other sciences into our research; or in other words: to contribute to the construction of a comprehensive intellectual framework like many of the other sciences do. Using the next slide I can explain. But let me mention before:


Our problem of "understanding the world", which for the public was mainly the clergy's task in previous centuries, always begins, in religions as well as in modern sciences, with the attempt to describe a temporal, historical process of evolution, genesis in a most general sense. For many scientists, and increasingly for the non-scientific public, absolute time began with a giant explosion, the Big Bang. Before there was nothing, that is, nothing real, only a potential for reality. Then arose: everything, radiation, matter, space and time.

In the left column you see a list of developments, evolutions, that describe our past. Cosmic evolution contains the origin of our universe, the blowing up of space and time, materialisation of smallest, small and huge structures, like clusters of galaxies, galaxies, stars and planetary systems. Geoevolution stands for the development of planets, their radiation fields, of planetary surfaces, their solid, liquid and gaseous spheres. A chemical evolution begins, fuelled by the sun and the inner heat of a planet ­ first of all our home planet Earth. Increasingly complicated molecules arise spontaneously on the planetary surface, on rocks, in the water and in the air. Chemical processes, reactions, lay the grounds for the arising of first forms of life: bioevolution sets in. Living creatures spread all over the whole planet at an enormous rate, considerably alter the composition of the earth's surface, even atmosphere, compete for natural resources and develop different species and populations. The evolution of populations, whether it be microorganisms, plants or animals, is the biological basis for the socioevolution also of mankind, who experience yet another final evolutionary jump with the beginning of a cultural development. The whole of evolutions can be understood as a gigantic spontaneously arisen self-organising process which time and again enters a new level for unfolding.

In the middle column you see a list of different theories, intellectual models that seek to scientifically explain these evolutions up to the very detail. The list is neither complete nor entirely uncontroversial, nor is it probably optimally put into words. I have tried, as a layman, to mark the most important theories with fairly comprehensible catchwords. We have a Big Bang theory, the central component of cosmology describing the destiny of the arisen matter and radiation. We've got a theory of tectonics. With tectonics I mean the theory of arising and movement of planets, planetary surfaces, of oceans and continents. Charles Darwin's theory of biological evolution by mutation, selection and adaptation describes all biotic processes on our planet in an enormously comprehensive way. By migration I mean the theory of the origin of humanity and its spreading since the Pleistocene, that is, during the last two million years. Finally, the theory of human language development explains the beginning of our culture.

In the right column research areas are listed that significantly contribute to the theories. Particle physicists shoot particles at each other with enormous energies and financial effort, not only to register and classify all kinds of particles, but because they are very well aware that they are looking deep into the past that way. The higher the energies the deeper the past, closer to the Big Bang. They are using energy as a measure for time. Their method allows the reconstruction of primordial cosmic processes. Astronomers look at the stars at an equal financial expense. They, too, don't merely want to describe, but exploit light velocity in connection with cosmological theories, above all Albert Einstein's general theory of relativity, to look deeply into the past. For us humans the present is limited to short distances, at far distances we observe the past. Planet researchers investigate the surrounding planets to find out what kinds of evolutions are likely and what it previously might have looked like on Earth. Mineralogists and climatologists join in reconstructing Earth history. They have several techniques at their disposal, like measuring isotope contents, echometry and excavations, to uncover the traces of Earth's historical processes past and buried. Palaeontologists also use the method of digging to learn more about our biological past from fossils of former biological forms of life. Lately the method of genetic analysis has been joining in to help uncover genealogical trees. This extremely useful technique is based upon a molecular variant of Darwin's theory to determine the degree of kin between different organisms through the similarity of related genes. Ontogenesis, that is evolutionary biology, whose object of research are single cells, organs or individuals, contributes enormously important perceptions to biogenesis. Various areas of biology, medicine, psychology, philosophy and information science attempt to explain the evolution of the most complicated organ, the human brain. Finally geographers and archaeologists use excavations, historians and scientists of the humanities use dateable chronicles and the calendar as a measure for time, to get onto the traces of human activity.



Ladies and Gentlemen, you've long since realised that I have left a blank space between 'chemical evolution' and 'chemistry'. We chemists do not yet have a theory of chemical evolution at hand, though we have a broad variety of means at our disposal, as can be seen from the great interspace around the word 'chemistry'. Chemical knowledge is very well being used by mineralogists, climatologists, palaeontologists and geneticists. Contrary to most other sciences chemistry is non-historical. All the theories and models we depend on need time only in very short, relative intervals. The evolution of processes on a time scale that exceed the processes themselves by orders of magnitude is neglectable because we assume that, within long time periods, the reaction partners be in a so-called thermodynamic equilibrium. This is of course a simplifying assumption, for the earth is not an isolated system. Since its origin around 4.5 or 5 billion years ago it has been within the sun's sphere of influence, but was also embedded in a relatively homogenous radiation, the 'sea of photons' with three Kelvin temperature of radiation. The sun's surface has an actual temperature of 5800 ­ the earth's about 260 Kelvin. Just imagine a heat engine: it takes a reservoir for heat of high temperature, like for example a steam boiler, and a reservoir for heat of low temperature, a river or lake or the surrounding air. Within this gradient the engine, which converts a part of the downflowing heat into useful mechanical labour, works by absorbing heat of higher temperature and releasing heat of lower temperature. Now, let's have a look at the system 'photon mill' Earth [6].

It absorbs a stream of energy of about 1017 Watt, photons of 5800 Kelvin, and releases the same amount of energy, 1017 Watt, but photons with a temperature of only 260 Kelvin. The thermodynamic strength of the driving power of this mill, about one Watt per square metre and Kelvin, generates molecular selforganisation and evolution on Earth. Thanks to this circumstance about 3.5-4.5 billion years ago increasingly complicated molecules and processes rather unusual to chemists occurred, like for example a temporal accumulation of reactive compounds that in a state of equilibrium are supposed to be unstable. Or a locally concentrated appearance of a certain class of molecules, though in an equilibrium they would long since be thinned out. Basically such abiotic-chemical processes can take place everywhere in the universe almost anytime, provided that certain simple parameters like pressure, temperature and flow of energy lie within favourable boundaries.

But searching for traces of past chemical processes is extremely difficult, for we chemists have no measuring device at hand for the time dimension, unlike physicists, astronomers, geologists, biologists, geographers etc. By past chemical processes I don't mean that they do not happen anymore now; but that, due to the superdominance of biotic processes, they are very hard to find. Consider that on our earth ­ many times declared almost dead but still exuberant with life ­ the incomparably greater part of naturally occurring molecules are of a biotic origin. What kinds of molecules were there before? To what purpose have they been used by cells and organisms later on? In what way were they thus reshaped? How did the first 'metabolisms' , circular reactions, arise? How did compartments? Membranes? Storage of information? Catalysts? Supporting structures? How did the first information-storing molecules replicate? How did this most fundamental interaction ­ I'm inclined to say: marriage ­ between the agents of information and the agents of function, nucleic acids and proteins that is, come about?

The scouting for prebiotic molecules, simple reactions and more complicated cyclic recurrent processes, for seeds that eventually led to such things as living cells ­ presumably, within a relatively short time period ­ can be carried out in yet another way. Leaving a blank background at the place of a chemical theory of evolution doesn't entirely fit the truth. If you have sharp eyes and take a close look at the pixels at this spot, you will discover, in proportion to the worldwide effort being invested in chemical research, some dots of a different colour. They symbolise efforts to acquire a theory of the spontaneous, abiotically arising of increasingly complicated molecules and reactions. If you had an electron microscope at your disposal ­ means: if you'd dive into the specialised literature ­ you would even discover wonderfully growing seeds of such a theory.

Not only that, you would see that the researchers responsible for it are often eminent authorities, masters of their subject. Scientists like Stanley Miller, Manfred Eigen, Hans Kuhn, Graham Cairns-Smith, Leslie Orgel, Guy Ourisson, Albert Eschenmoser, Günter Wächtershäuser, to mention a few. Among them are 'molecular palaeontologists' who search for traces of early biotic molecules, as well as experimentalists who develop theories for prebiotic chemistry based on their experimental results ­ I call them 'reconstructors' ­ and theoreticians who on the grounds of calculations and/or simulations propound theses which they thereupon seek to falsify or verify ­ the 'logicians'. Of course I am exaggerating a little with the pixels, for so I want to emphasise that in my opinion much too little research is being done in that direction ­ although there are a few very impressive papers on prebiotic and early biotic chemistry ­ and that neither our students nor the rest of the public are being sufficiently informed about it. It would be nice if not only a few extraordinarily talented researchers were to take care of this subject, but we common academic chemists, too.

To make myself clear: I am not propagating here that every chemist should carry out prebiotic or early biotic research ­ that would be unrealistic and probably not at all helpful for the case ­ but that we should deal more with intellectual models of other natural sciences, especially those concerning the component of time, and that we convey at any rate to our students insights from chemical experiments that, for example by chemical reconstruction, could help construct a theory of chemical evolution. Public relations will take care of the rest.

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Finally I should like to quote Günter von Kiedrowski who made a point of it once: «Organic chemistry is not, like it has been put before, a mature elderly lady who thinks herself the most important, but a still young mother that actively cares about her children's progress.»

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* The public habilitation lecture 'Ein Plädoyer für Chemie' was held by the author on June 28th 1996 at the University of Basel, Switzerland. The German text was published in Chimia 1997, 51 (3), 69-75, and translated into English by Martin T. H. Werner (unless stated otherwise). The images 'Synthesis/Analysis', 'Evolutions, Theories, Disciplines' and 'Photonmill Earth' were designed by Andreas Martens von Salzen. The photos of the author were taken by Mick Dellers.

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REFERENCES

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[1] Chem. Eng. News 1996, 74 (1), 2 BACK

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[2] authorised translation from: Chimia 1996, 50 (5), 189-190 BACK

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[3] Friedrich Dürrenmatt, "The Quarry" ("Der Verdacht", translated into English by Eva H. Morreale), Jonathan Cape, London, 1962, p. 143. BACK

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[4] Karl R. Popper, "The Logic of Scientific Discovery", Hutchinson & Co., London, 1959, p. I5; in German: "Logik der Forschung", J.C.B. Mohr (Paul Siebeck), 2. erweiterte Auflage, Tübingen, 1966, S. XVI. BACK

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[5] translated from M. Berthelot, "Chimie organique fondée sur la synthèse", Mallet-Bachelier, Paris, 1860, vol. 2, p. 811. BACK

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[6] after: W. Ebeling, R. Feistel, "Chaos und Kosmos: Prinzipien der Evolution", Spektrum Akademischer Verlag, Heidelberg, Berlin, Oxford, 1994. BACK