Source of Theories
Murray Gell-Mann noted that “A successful new theoretical idea typically alters and extends the existing body of theory to allow for observational facts that could not previously be understood or incorporated. It also makes possible new predictions that can some day be tested.” Often in science, any significant contribution uncovers some serious flaw in a long-accepted and respected idea.
There are no hard and fast rules by which a theory is constructed in science. The formulation of a scientific theory is a supremely creative act, constrained only by the condition that its ultimate results must be in accordance with observed facts. Psychologists and philosophers have reflected on the process of creativity. A recent comment is that “The creative achievements of human culture are the products of memetic evolution, just as the creative achievements of the biological world are the products of genetic evolution.” This is more a reflection than a scientific explanation: it merely says that every creative product is a slightly or significantly modified version of something that is already there. However, when the painter Dali was once asked if it was hard to paint a picture, he is said to have replied, “No, it is either easy or impossible.” The point is, creativity is an innate faculty which cannot be taught or learned.
Analogies have been powerful in the formulation of theories. Some scientists have regarded analogy not merely as an aid to understanding, but as an indispensable part of any theory. This was very prevalent in the nineteenth century when Newtonian mechanics had proven itself to be remarkably successful. As a result, explanations often meant expressing situations in terms of a mechanical model. The billiard ball analogy helped in the development of the kinetic theory of gases. The analogy of vortices from smoke rings led Lord Kelvin to attempt electrical theories on a vortex model, but this failed. This great physicist of the nineteenth century refused to accept Maxwell’s elegant mathematical theory of electromagnetism on the ground that it could not be pictured in terms of a mechanical analogy. He famously said: “I never satisfy myself until I can make a mechanical model of a thing. If I can make a mechanical model, I understand it. As long as I cannot make a mechanical model all the way through I cannot understand, and that is why I cannot get the electromagnetic theory of light.”
The Rutherford model for the hydrogen atom was based on an analogy with planetary orbits around the sun. But analogies have also sometimes misguided scientists. Thus the caloric theory of heat, which was current in the 18th century and has now been discarded, was developed in analogy with hydrodynamics, and thus regarded heat as a fluid.
Occasionally, no more than an intelligent guess has originated a physical theory. This often happens when order is to be discovered in a maze of observed data. The recognition of specific relationships between the wavelengths of radiation – the so-called Balmer series – in the hydrogen spectrum was the result of intelligent guess work.
When the guessing process reveals some intrinsic feature of the world which goes beyond merely telling us about what could have been gathered by intelligent guessing, we have a case of a flash of insight. Many theory builders, as also artists and composers, have reported on how insights and inspirations have come to them. Consider the following: “When I feel well and in a good humor, or when I am taking a drive or walking after a good meal, or in the night when I cannot sleep, thoughts crowd into my mind as easily as you could wish. Whence and how do they come? I do not know and I have nothing to do with itâ€¦.” These were written by Wolfgang Amadeus Mozart. But these words could have been written by many creative scientists as well. It is true that a good deal of preliminary work, i.e. a study of the problem in depth, struggles to clarify the situation, considerable hours of reflection, etc., are needed before the flash occurs.
The discovery of the ring structure of the benzene molecule – a major revolution in organic chemistry – by August KekulÃ© is often cited as a classic example of this. KekulÃ© is said to have had a first insight into the question while on a bus ride in London. Suddenly it occurred to him that some organic compounds must have their various carbon atoms connected to each other in chain-like links. Some years later, in 1865, his imaginative eye saw pn a dream “long rows, variously, more closely, united; all in movement, wriggling and turning like snakes. And see, what was that? One of the snakes seized its own tail and the image whirled scornfully before my eyes. As though from a flash of lightning I awoke; this time again I occupied the rest of the night in working out the consequences of the hypothesis.â€
The stories of Archimedes running stark naked from the public bath upon recognizing his hydrostatic principle and of Newton discovering gravitation when an apple fell on his head do not rest on any historical events, but they illustrate the role of flashes of insight in the formulation of theories.
Sometimes, especially since the rise of sophisticated theoretical physics, the mathematical aspects of physics have given rise to altogether new theories. Thus, for example, in trying to express the empirically known laws of electromagnetism in a systematic mathematical form, Maxwell was obliged to introduce the concept of a displacement current. This had a major impact in our understanding of electromagnetism. The remarkable thing here was that from purely mathematical analyses, Maxwell was able to uncover the existence of electromagnetic waves, and to recognize light as being an electromagnetic radiation.
In attempting to find an acceptable mathematical function whose graph would correspond to the curves plotted from the data of black body radiation, Max Planck hit upon the quantum theory of radiation which revolutionized twentieth century physics. It is not always recognized that atomic, quantum, and nuclear physics, all of which have radically transformed our worldviews as also the face of human civilization, emerged from theoretical and mathematical probing into nature.
There arise occasions when it becomes difficult to accept or interpret some experimental results in terms of the currently accepted framework of science. The scientist is then at a loss to find out what has gone wrong. Under such circumstances, a clarification of the paradox could result from some new and major scientific discovery, often an altogether new paradigm in the scientific worldview. A classic example of this relates to the problem of the ether-drift. In the late nineteenth century, physicists had accepted the notion of an all pervading ether in which celestial bodies moved (somewhat like ships on an ocean), through which light and other forms of radiation propagated between celestial bodies. Extremely delicate experiments designed to put into evidence such an ether failed to reveal any such thing. This was incompatible with the notions of absolute space and absolute time. Almost twenty years later, in 1904, the theory of special relativity solved the paradox, rejecting in the process some of the basic assumptions of classical Newtonian physics.