Clays are sedimentary mineral deposits, and we know that there are clays all over the world. Natural catastrophes like clay avalanches represent parts of our own close history. We know for example that large parts of the campus of The Norwegian University of Science and Technology (NTNU), where the present author is spending many of his working days, are built on top of a clay hill. Less than that can make one tremble and shake! Geologists and geo-technicians possess traditional good knowledge about natural clay deposits, and about stability and control of natural clays. However, that is not what this talk is about, but rather I will speak about uses of clays, either spontaneously by nature itself, or by humans. We are also going to try to use clays as illustrations of history, status, new trends, and the future of materials -science and -technology.

Clays represent one of many natural materials that human beings all over the globe, and since the beginning of human history, have collected from the natural environment, and used. One traditional application of clays is in ceramics for use in arts and pottery, clay sculptures for example. In fact, the oldest "surviving" work of art known, is made from clay, namely a small fertility figurine from the Czech Republic, which apparently have been dated to 23000 years AC. Since clays are inorganic materials, one cannot just simply carbon-date clay objects, but in this particular case, the dating comes from mammoth bone ash, which must have been included in the ceramics when the artist shaped the figurine some impressively 25000 years ago.

Porcelain was invented by the Chinese, like so many other natural material products we have been using in our western culture during the last 5-600 years, after Marco Polo managed to get himself back to Italy again. European King's and their male and female friends were of course impressed by the beautiful porcelain, and during the 1600-1700's attempts went on all over continental Europe with the purpose of revealing the Chinese' porcelain recipe. History tells that the recipe remained a mystery until a Court Chemist with the name Bottger at the Court of King August "The Strong One" of Sachsen (in today's Germany), one day in 1710 noticed that his powdered wig had become unusually heavy. The story further claims that the person being responsible for wig powdering in the King's Court recently had begun to use a local mineral powder instead of flour, which was the usual wig powder in those days. The mineral powder turned out to be extraordinary pure kaolinite, which is the name of the type of clay commonly used in clay ceramics and porcelain. The result was that the Kingdom of Sachsen became very wealthy from porcelain production during the 1700's, before others also got hold of the same knowledge. So, what's the moral to this story? Well, one thing is that certain clays may be used as wig powder, but much more important is that practical uses of materials based upon basic knowledge, can give wealth, influence and The Good Life even for a whole society which does not possess any natural oil reservoirs!

Mankind's history is intimately linked to the use of materials. It has been said that she who controls the important materials of her time, controls the world around her. Our occasionally wild ancestors, the Vikings, possessed knowledge about modern advanced uses of materials in weapons and ships, and it was this that constituted the real and absolutely necessary physical base for the blooming Viking culture. Closer to our times, USA is a superpower based upon advanced knowledge about materials, and this has represented the foundation for moon landings, cold and warm warfare, modern computer technology, and so on.

In Norway, the economy is based upon raw natural products, like in most developing countries, and the natural product we earn the most money from these days, is oil. We collect our wealth from reservoirs underneath the seafloor, often drilling holes 3-4 kilometers straight down, and some times 7-8 kilometers horizontally, and most of the time one must bore through structures and formations that actually may consist of more than 50% clay. Bore hole collapses make the process very expensive and cost oil companies, and thus Norway, enormous sums each year.

Clays are also important during the drilling process, in the so-called drilling muds. Such drilling fluids are technologically essential disgusting muds which are being used during well drilling in order to cement the bore hole walls, and also in order to flush out the loose particles produced during drilling. Clays are the most important solid ingredients in the modern more environmentally friendly drilling muds. To understand clay rich formations, and thus how water, oil and clay based drilling muds interact with such formations, is therefore practically very important and relevant for Norwegian economy. And the way to go about these problems, is obviously to first gain fundamental knowledge about how idealized clays and clay mixtures behave, become fluidized, and stabilized at the temperatures and pressures corresponding to the ones active underneath the North Sea.

After the oil has been brought up to the surface, it has to be treated in an oil refinery, in order for you to be able to lubricate your bicycle, your car or your sewing machine for example. One important part of oil refining is catalysis, which in this case may mean that hydrocarbon molecules must be broken down into useful smaller molecules. A catalyst is a substance that by its presence accelerates a process, without itself being an integral part of the start- or the end- product. Surfaces of clay particles are good catalysts among other things for cracking of hydrocarbon chains in oils, and it is an active and modern research field of its own to make porous materials with large effective surface-areas for such use.

Porous media have large accessible surfaces inside a limited volume. Crumble a sheet of paper into a little paper ball, and you realize that the paper ball takes much less space than the original sheet of paper, even if the paper area is the same. These kinds of actual clay based porous media do not only have pure practical use for oil refining, but are also being used by physicists in order to understand universal properties of porous media, and to understand better flow and transport of fluids in porous structures.

Another practical use of porous clay, are water coolers, for wine for example, which are popular in the south of Europe among other places. Water penetrates into the porous walls of the cooler, and evaporates from the outer free surface. The heat of evaporation is supplied from the water inside the cooler, which therefore stays a few degrees below the temperature of the surroundings.

The famous scientist and physicist Bernal suggested in the 1940's that clay surfaces could have been the essential catalyst for that life, as we know it on earth, came to be in the first place. The idea is that during one period of time in the past, before life, the surface of the earth consisted of a collection of minerals, including clays, plus water and some small molecules. One imagines that inside natural porous clay structures, small molecules may be forced to stay close to each other long enough to merge into larger units, and that these larger units may reproduce themselves, that is, make life in the clay. A few years ago, in 1997, a group at Rensellaer Polytechnic Institute in New York State, succeeded in creating life in the form of the molecule RNA, based on such clay controlled catalysis. This experiment obviously does not prove that life on earth emerged in this fashion, but it does not exclude the possibility, which is one among several alternatives being scientifically debated.

Creation of Man from clay is by the way suggested both in the Bible and in the Koran, but let us instead return to real practical life: For example, did you know that clays are important ingredient in cosmetics, toothpaste, cleansers, paints and so on? All these products belong to a large class of materials which behave like elastic solids when left alone, or exposed to tiny disturbances, but which flow like liquids when the forces exceed a float point, which may vary from one substance to another. Paint for example, should just sit on the brush when the brush is dipped in the bucket, but one should be able to apply the paint to the wall without becoming exhausted, and when the paint is on the wall, it should not flow, but just sit there peacefully to dry. Clays are mixed into paints at the end of the production process in order to fine tune precisely these important flow properties.

Materials with a float point are called shear thinning, and such shear thinning materials are themselves a part of a larger and at the moment very active area within the physical sciences, namely the physics of complex fluids. Other examples of shear thinning materials are foods like butter, caviar or ketchup.

Take a bottle of ketchup, and hold it upside down, while it is open! Nothing happens. In order to get the ketchup out, you must hit at the bottom of the bottle. But you must hit with sensitivity and with subtle feeling! If you hit too lightly, nothing happens. If you hit too hard, you have a local environmental problem on your pants, literally! Now, repeat the experiment with a bottle of red wine. Now you do not have to hit at all. Thus it is evidently more than taste and culture that distinguish ketchup from wine. Notice however: I did not say that there are clays in ketchup!, but merely that ketchup like clays and many other substances, are complex fluids, which have something visible in common, namely float point and flow properties.

Think about what happens when an artist spins and shapes a piece of clay into a pot before it is being baked hard in the furnace. This represents another example of shear thinning and complexity in practice. Only a soft touch is needed to shape the piece of clay into a pot, but the shaped pot is standing there, it does not flow and collapse before being placed into and baked in the furnace. What is going on? Wet artist clay is a mixture of small clay particles in water, and some other ingredients. The shaping of the clay from just a shapeless piece into a useful pot, or a sometimes beautiful sculpture means reorganization of clay particles internally relative to each other, in other words, internal structural changes that are visible to us in two completely different macroscopic forms, piece of clay, and pot or sculpture. And this is precisely what important aspects of everyday fundamental clay- and complex fluid- science are about, namely attempts to understand which internal particles get reorganized, which internal forces are at work between the same particles, and what is the relation between microscopic structure and macroscopic form and stability. And when one has understood that: How does one control material properties in such a way that this new knowledge may be applied to something useful for those who might be interested in that.

Ketchup contains so many components that it is almost impossible to describe. Clays found in nature are not clean either, meaning that they contain foreign particles that may have measurable influence on clays properties if not removed. This is the case even for the most pure natural clay deposits, including the kaolinite that Bottger found in Sachsen in 1710.

So, how does one extract the essence from the mess in this case? The answer is synthetic clays! Physicists and chemists working with basic clay science are focusing on pure synthetic clays, and we try to understand these clays to the best of our abilities and often within narrow boundaries of lousy economy. It is possible to purchase synthetic clays, and a few of them are being made in large quantities for industrial use. Not only is it important to understand clays as materials better, but another and more important point is that these pure synthetic versions can be used as physical model systems in which to study universal physical phenomena within complex systems and materials generally. In other words, one learns something about ketchup, caviar, medicines with float point, and so on, by studying synthetic clays.

So, what are clays? We already mentioned microscopic particles. The main ingredient in pottery and porcelain, namely kaolinite, consists of many small particles, of order of magnitude micro-meters, which means one thousandth of milli-meters. It is these particles that make structures in water, and which may be moved relative to each other, during the creative sculpturing process.

If one focuses on a single particle, and looks at it in an advanced microscope, one finds structure at that level also, that is internal particle structure. One single kaolinite particle can be described as a kind of deck of cards, in which each single "card" is one nano-meter thick. One nano-meter is one thousandth of a micro-meter, which is one thousandth of a milli-meter. In other words, one such kaolinite particle consists of a stack of approximately 1000 "cards". Looking even more closely, one may identify structure internally in the "cards" also, in the form of atomic organization. The so-called "cards" are thus structurally "identical", where all the atoms are organized in a known and experimentally verifiable crystal lattice.

Clays may be divided into two classes, namely clays that swell or not. Kaolinite represents one example of a non-swelling clay, meaning that if one adds water to such a clay, the "deck of cards" particles remain intact, and it is thus not possible to extract the "cards" from the "deck of cards" in this case. The most frequent type of clay in for example Norwegian soil, illite, does not swell either.

However, it is the swelling clays that are the most important ones for control of the flow properties of paints, cosmetics and cleansers. It is the swelling clays that cause the largest problems associated with bore hole collapse underneath the North Sea, and that enter into drilling muds. It is also the swelling clays that form the basis for porous catalytic structures, and thus also could have been instrumental for the origin of life.

From a fundamentally interested physicist's point of view, it is obviously much more fun to play with single "cards" than with "decks of cards that are glued together", among other things because of the fantastic structural richness inherently built into a system of such platelet shaped interacting particles. One can study lots of interesting physics with ensembles of spherical particles, and physicists have done that over and over and over again, but the world is not only made up of spheres! If you think that cows are spherical, you have become a mathematician, NOT a physicist!

The physical systems we are concerned with now are therefore macroscopic forms built from structures based upon sheets or "cards", that each are one nano-meter thick. Did you already forget how much is one nano-meter? One thousandth of one thousandth of a milli-meter. The atomic structure internally in the sheets is known for the swelling clays also, and it is basically this internal sheet structure that distinguishes different types of clays from each other. The areas of sheets vary from one clay type to another. For example, one of the most studied and interesting synthetic clays has the factory name laponite. The laponite particles all have the same size, that is, they all are one nano-meter thick disc shaped sheets, and they all have a diameter of 25 nano-meter.

Many people get surprised when shown that clay samples made out of laponite are completely transparent, simply looking like, and feeling like, stiff water. Hmmm, transparent clay, pretty strange matter. The reason for this transparency is that the particles are too small to scatter visible light. Visible light has wavelengths of order of magnitude micro-meters, that is, thousandths of milli-meters, and thus visible light will be scattered from particles or compact structures that are of the order of magnitude micro-meters. Most of such laponite gels are actually water. One can make stiff transparent gel samples from as little as 1% clay, and as much as 99% pure water. Addition of salts, ordinary table salt for example, influences and determines nano- and micro- structure, and thus flow-properties and transparency of such laponite gels. One has an overall understanding of what happens when salts are added to such systems, but a fundamental and detailed experimental and theoretical description is still lacking, and a lot of detailed scientific work remains before a complete understanding may be established.

It is well known that salts are added in order to stabilize clay rich soils. The reason for this effect of salts, that is, ions, that is, charged atoms, on clays, is that the clay particles themselves are charged, negatively charged on the up and down sides, and positively charged along the edge. Plus and minus attract each other, like a he and a she in a bar. This means that an effective clay particle i water in reality consists of the solid particle itself, plus a cloud of ions that neutralizes, surrounds and is bound to the charged clay particle. The more salt added to the water, the closer to the particles are the ions that are sufficient for neutralization, and the smaller is the resulting effective particle size. The ionic clouds from different particles may overlap. Ions may in one moment belong to one clay particle, in the next moment to another, and in this way, such effective clay particles may interact with each other, or in other words, become "glued" together, and thus spontaneously self-organize into different more or less compact structures.

The most important experimental techniques in use for studying such systems, are so-called scattering techniques, that is, scattering of visible light, x-rays, or neutrons, because such waves or particles have a wavelength, that is a "unit of measure" at a length scale comparable to the structures of interest. By means of such techniques, one may study how structures are formed over time, how the structures break down under externally applied forces, how the structures depend on temperature and pressure, and so on, In concert with structural studies, one may also investigate resulting macroscopic properties, like elasticity and flow.

Synthetic laponite is the only clay one knows about that has equal particle sizes. All other known clays have degrees of variation in the particle size. It has been found that the earth's gravitational field is an active and relevant external parameter for establishing stable structures in clays with varying particle sizes. This has inspired renewed efforts into type of work first done in the 1930's by the famous scientist and Nobel Prize winner in chemistry, Langmuir. Langmuir was among the first who experimentally tried to find so-called liquid crystal structures in a physical system, and the physical system he worked with was a naturally swelling clay called montmorillonite. With today's modern experimental techniques available, one realizes that time has arrived to reconsider many of Langmuir's conclusions specifically about clays. However, the most important point in this context, is that his and other's ideas at that time about ensembles of non spherical particles, that is, rods or discs for example, give possibilities for a richness of verifiable self-organized structures and formations that are impossible to achieve by means of spheres. The famous Norwegian physicist and Nobel Prize winner Onsager, made the theoretical foundation for such phenomena, in an article he published in 1949. Since that time, and still today, there has been invested an enormous, very broad and deep basic international effort into the studies of physical properties of liquid crystal systems.

LCD's, or Liquid Crystal Displays, as known from today's laptop computers for example, represent examples of modern developments and applications of these original fundamental ideas. Such LCD monitors are physically based upon that certain rod shaped molecules can be aligned in an applied external electrical field, and at the same time that the structures that may be stabilized in this manner, have different optical properties.

When one sees a little laptop computer, it's just there, one can simply buy it in the store as a finished product, and it is too easy to forget the history behind the technology, and especially the long time-consuming process behind. Not far into the future, most homes are going to have flat large LCD TV monitors on the wall in their living rooms. The history behind liquid crystal monitors demonstrates therefore with clarity that these kinds of technologies are long-term results of knowledge only for the sake of knowledge itself. Neither Langmuir, nor Onsager, could have imagined TV monitors or PC's when they thought of spontaneous organization and ordering of anisotropic objects, and it was not until in the 1970's and 80's that one started thinking practically in terms our day's flat monitor technology.

Here, it's again important to emphasize that I do not claim that clays may be used for making a new kind of TV monitors. Clay particles are too big for that, and the time it would take to switch from one optical state to another, would be too long for practical use. This is simply not the point! The point is, however, that clays and liquid crystal systems both are anisotropic complex soft materials, and both can be studied in parallel mathematically, and experimentally, with the same techniques. By studying one, one learns something about the other, and vice versa, in addition to new knowledge about ketchup and many other things.

Wherever we look out through the window, we discover that the world is complex. The world consists of many examples of highly organized systems on all levels: Wet or dry clays, mountain-ridges, sand dunes, stripes on a tiger, schools of fish, stock markets, and real ecosystems, like ourselves. In order to extract physical knowledge from complex systems, one must focus on the right level of description. It's simply not possible to model bulldozers with quarks!!, and in order to model macroscopic clay, one must start with the clay "cards" and build decks of "cards" and houses of "cards". In other words, one cannot start with the atoms or the electronic properties of single "cards". That belongs to a different research field within physics, with other interesting questions and problems.

Inclusion of clay materials into the context of modern materials science, represents a scientific trend in our times. One has since the Second World War mainly worked with the development of and new applications of synthetic materials, for example plastics, or liquid crystals. The "traditional" materials clay, sand, wood, leather, and so on, have been in practical use all the time, but one has somehow forgotten to try to understand them? Now, time has come to use all the collected synthetic materials knowledge to understand the spontaneous nature itself better. In fact, it is often the case, that materials that nature itself has processed in its own environmentally clean way, often are better and stronger than the materials that humans can fabricate with modern "state-of-the-art", and often very energy consuming technologies.

Take spider webs and silks for example. Unroll a silk cocoon, and you have an 800 meters long continuos silk fiber thread. Spider webs and silk fibers are the strongest fibers known. The fiber technological possibilities are large, and for basic science there is a great potential in silk fibers as physical biological model systems for proteins. This represents an example of a young coming scientific field within complexity, which is called "bio mimics" or "bio imitation", which means copying nature itself, both with respect to production process, and also with respect to product. For example, there is today research going on which is trying to establish methods for making real silk fibers artificially, produced by some kind of artificial spiders.

Spider webs and clays are both natural complex materials, that are integrated parts of earth's biosphere, in other words, good representatives for modern complex science, and therefore the materials of the future. Water is essential in this respect! Life dies without water, and water is thus an integrated part of the materials that constitute the foundation of life, in the same way that water is integrated into clay formations. In order to understand biological physics, it is essential to understand water, which surprisingly to many, is not understood as a material either. In particular, there are big mysteries associated with the behavior of water near or inside other materials, and this is something we practically address within our own clay related scientific work. In collaboration with scientists at Brookhaven National Laboratory, USA, we perform detailed x-ray studies of the behavior of single mono-layers of water trapped inside synthetic clay structures.

It has been suggested that future materials science more and more will explore the "border land" which lies in between advanced uses of "dead" materials, and biology. Actual and relevant examples of applied research within this "border land", could simply be cut out from the daily news recently: It was reported that for the first time, one had succeeded in attaching a camera directly to the brain, thus giving a blind man his eyesight back. In another case, a paralyzed patient had gotten back his ability to communicate after having had a capsule with miniature electronics surgically implanted into his brain. Isn't that smart?

About the smartest hard non-biological "thing", one can buy in the store these days, is a laptop computer. Smart material represent another complex field which is blossoming "out there" in today's world, but which only a few people in Norway have discovered the existence of yet. Smart materials may be defined as an integration of a detector, a processor, and an activator. The detector "feels" a change in the environment, and transmits that information via a processor to the activator, which in turn puts an action, as we want it, into real "life". An LCD monitor is a smart activating device, while other examples of that are shear thinning materials in which the float point may be moved by means of an external electric or magnetic field, in other words, one may decide by means of a switch whether the material is solid and elastic, or whether it flows like a liquid. It has been shown that clay suspensions, may behave in this manner, although clays do not yet perform like the best materials of this type. Such materials one may for example think of using for smart clutches in cars, or for making houses that are immune towards earthquakes, by enabling adjustment of the walls' stiffness "opposite" to the quake waves, or many other "strange" things. "Out in the world", there is now active research going on with the goal of trying to make integrated smart materials, that is, smart materials in which both detection, processing and activation, are parts of the same material. A smart material knows how to behave, while an old fashioned stupid material simply sits there, just like another chair!