Sunday, April 28, 2013

Mathematical Metaphors

Theories in all areas of science tell us something about the world. They are images, or models, or representations of reality. Theories tell stories about the world and are often associated with stories about their discovery. Like the story (probably apocryphal) that Newton invented the theory of gravity after an apple fell on his head. Or the story (probably true) that Kekule discovered the cyclical structure of benzene after day-dreaming of a snake seizing its tail. Theories are metaphors that explain reality.

A theory is scientific if it is precise, quantitative, and amenable to being tested. A scientific theory is mathematical. Scientific theories are mathematical metaphors.

A metaphor uses a word or phrase to define or extend or focus the meaning of another word or phrase. For example, "The river of time" is a metaphor. We all know that rivers flow inevitably from high to low ground. The metaphor focuses the concept of time on its inevitable uni-directionality. Metaphors make sense because we understand what they mean. We all know that rivers are wet, but we understand that the metaphor does not mean to imply that time drips, because we understand the words and their context. But on the other hand, a metaphor - in the hands of a creative and imaginative person - might mean something unexpected, and we need to think carefully about what the metaphor does, or might, mean. Mathematical metaphors - scientific models - also focus attention in one direction rather than another, which gives them explanatory and predictive power. Mathematical metaphors can also be interpreted in different and surprising ways.

Some mathematical models are very accurate metaphors. For instance, when Galileo dropped a heavy object from the leaning tower of Pisa, the distance it fell increased in proportion to the square of the elapsed time. Mathematical equations sometimes represent reality quite accurately, but we understand the representation only when the meanings of the mathematical terms are given in words. The meaning of the equation tells us what aspect of reality the model focuses on. Many things happened when Galileo released the object - it rotated, air swirled, friction developed - while the equation focuses on one particular aspect: distance versus time. Likewise, the quadratic equation that relates distance to time can also be used to relate energy to the speed of light, or to relate population growth rate to population size. In Galileo's case the metaphor relates to freely falling objects.

Other models are only approximations. For example, a particular theory describes the build up of mechanical stress around a crack, causing damage in the material. While cracks often have rough or ragged shapes, this important and useful theory assumes the crack is smooth and elliptical. This mathematical metaphor is useful because it focuses the analysis on the radius of curvature of the crack that is critical in determining the concentration of stress.

Not all scientific models are approximations. Some models measure something. For example, in statistical mechanics, the temperature of a material is proportional to the average kinetic energy of the molecules in the material. The temperature, in degrees centigrade, is a global measure of random molecular motion. In economics, the gross domestic product is a measure of the degree of economic activity in the country.

Other models are not approximations or measures of anything, but rather graphical portrayals of a relationship. Consider, for example, the competition among three restaurants: Joe's Easy Diner, McDonald's, and Maxim's de Paris. All three restaurants compete with each other: if you're hungry, you've got to choose. Joe's and McDonald's are close competitors because they both specialize in hamburgers but also have other dishes. They both compete with Maxim's, a really swank and expensive boutique restaurant, but the competition is more remote. To model the competition we might draw a line representing "competition", with each restaurant as a dot on the line. Joe's and McDonald's are close together and far from Maxim's. This line is a mathematical metaphor, representing the proximity (and hence strength) of competition between the three restaurants. The distances between the dots are precise, but what the metaphor means, in terms of the real-world competition between Joe, McDonald, and Maxim, is not so clear. Why a line rather than a plane to refine the "axes" of competition (price and location for instance)? Or maybe a hill to reflect difficulty of access (Joe's is at one location in South Africa, Maxim's has restaurants in Paris, Peking, Tokyo and Shanghai, and McDonald's is just about everywhere). A metaphor emphasizes some aspects while ignoring others. Different mathematical metaphors of the same phenomenon can support very different interpretations or insights.

The scientist who constructs a mathematical metaphor - a model or theory - chooses to focus on some aspects of the phenomenon rather than others, and chooses to represent those aspects with one image rather than another. Scientific theories are fascinating and extraordinarily useful, but they are, after all, only metaphors.

Saturday, February 9, 2013

MOOCs and the Unknown

MOOCs - Massive Open Online Courses - have fed hundreds of thousands of knowledge-hungry people around the globe. Stanford University's MOOCs program has taught open online courses to tens of thousands students per course, and has 2.5 million enrollees from nearly every country in the world. The students hear a lecturer, and also interact with each other in digital social networks that facilitate their mastery of the material and their integration into global communities of the knowledgable. The internet, and its MOOC realizations, extend the democratization of knowledge to a scale unimagined by early pioneers of workers' study groups or public universities. MOOCs open the market of ideas and knowledge to everyone, from the preacher of esoteric spirituality to the teacher of esoteric computer languages. It's all there, all you need is a browser.

The internet is a facilitating technology, like the invention of writing or the printing press, and its impacts may be as revolutionary. MOOCs are here to stay, like the sun to govern by day and the moon by night, and we can see that it is good. But it also has limitations, and these we must begin to understand.

Education depends on the creation and transfer of knowledge. Insight, invention, and discovery underlay the creation of knowledge, and they must precede the transfer of knowledge. MOOCs enable learners to sit at the feet of the world's greatest creators of knowledge.

But the distinction between creation and transfer of knowledge is necessarily blurred in the process of education itself. Deep and meaningful education is the creation of knowledge in the mind of the learner. Education is not the transfer of digital bits between electronic storage devices. Education is the creation or discovery by the learner of thoughts that previously did not exist in his mind. One can transfer facts per se, but if this is done without creative insight by the learner it is no more than Huck Finn's learning "the multiplication table up to six times seven is thirty-five".

Invention, discovery and creation occur in the realm of the unknown; we cannot know what will be created until it appears. Two central unknowns dominate the process of education, one in the teacher's mind and one in the student's.

The teacher cannot know what questions the student will ask. Past experience is a guide, but the universe of possible questions is unbounded, and the better the student, the more unpredictable the questions. The teacher should respond to these questions because they are the fruitful meristem of the student's growing understanding. The student's questions are the teacher's guide into the student's mind. Without them the teacher can only guess how to reach the learner. The most effective teacher will personalize his interaction with the learner by responding to the student's questions.

The student cannot know the substance of what the teacher will teach; that's precisely why the student has come to the teacher. In extreme cases - of really deep and mind-altering learning - the student will not even understand the teacher's words until they are repeated again and again in new and different ways. The meanings of words come from context. A word means one thing and not another because we use that word in this way and not that. The student gropes to find out how the teacher uses words, concepts and tools of thought. The most effective learning occurs when the student can connect the new meanings to his existing mental contexts. The student cannot always know what contexts will be evoked by his learning.

As an interim summary, learning can take place only if there is a gap of knowledge between teacher and student. This knowledge gap induces uncertainties on both sides. Effective teaching and learning occur by personalized interaction to dispel these uncertainties, to fill the gap, and to complete the transfer of knowledge.

We can now appreciate the most serious pedagogic limitation of MOOCs as a tool for education. Mass education is democratic, and MOOCs are far more democratic than any previous mode. This democracy creates a basic tension. The more democratic a mode of communication, the less personalized it is because of its massiveness. The less personalized a communication, the less effective it is pedagogically. The gap of the unknown that separates teacher and learner is greatest in massively democratic education.

Socrates inveighed against the writing of books. They are too impersonal and immutable. They offer too little room for Socratic mid-wifery of wisdom, in which knowledge comes from dialog. Socrates wanted to touch his students' souls, and because each soul is unique, no book can bridge the gap. Books can at best jog the memory of learners who have already been enlightened. Socrates would probably not have liked MOOCs either, and for similar reasons.

Nonetheless, Socrates might have preferred MOOCs over books because the mode of communication is different. Books approach the learner through writing, and induce him to write in response. In contrast, MOOCs approach the learner through speech, and induce him to speak in response. Speech, for Socrates, is personal and interactive; speech is the road to the soul. Spoken bilateral interaction cannot occur between a teacher and 20 thousand online learners spread over time and space. That format is the ultimate insult to Socratic learning. On the other hand, the networking that can accompany a MOOC may possibly facilitate the internalization of the teacher's message even more effectively than a one-on-one tutorial. Fast and multi-personal, online chats and other networking can help the learners to rapidly find their own mental contexts for assimilating and modifying the teacher's message.

Many people have complained that the internet undermines the permanence of the written word. No document is final if it's on the web. Socrates might have approved, and this might be the greatest strength of the MOOC: no course ever ends and no lecture is really final. If MOOCs really are democratic then they cannot be controlled. The discovery of knowledge, like the stars in their orbits, is forever on-going, with occasional supernovas that brighten the heavens. The creation of knowledge will never end because the unknown is limitless. If MOOCs facilitate this creation, then they are good.