2005: The World Year of Physics

Centennial anniversary of Albert Einstein's Miraculous Year

by Kirthi Tennakone, Institute of Fundamental Studies

THE United Nations have declared the year 2005 as the World Year of Physics. It is timed to celebrate the centennial anniversary of Albert Einstein's Miraculous Year in which he laid the foundations for a new era of science with profound implications in technology, culture, philosophy and politics.

In 1905, Albert Einstein, then working as an obscure clerk at the Patent Office in Bern, Switzerland, published three seminal papers on the Relativity of Motion, the Photoelectric Effect and Brownian movement. The first gave rise to the theory of relativity resolving an inconsistency between the previous classical theories of mechanics and electromagnetism founded by Isaac Newton and Clerk Maxwell respectively. Newton's theory was even sufficiently accurate to analyze perturbations in Uranus' orbit and attribute them to the influence of an unknown planet. Calculations based on his theory made it possible for astronomers to pinpoint the position of Neptune in the sky and then actually see it through a telescope. This was how Neptune was discovered.

Single framework

Nearly two centuries later, Clerk Maxwell combined electricity and magnetism into one single framework that included the theory of light as well. What Einstein did was to replace Newton's mechanics with relativity permitting its marriage to electromagnetism. The crucial point he had recognized, which seemed very strange in the beginning, was the constancy of the speed of light irrespective of the motion of the observer or that of the light source. If you walk forward in the compartment of a moving train, your speed as measured by a man standing on the platform is your speed relative to the compartment as measured by a seated passenger plus the speed of the train. However, if a beam of light passes by, both the seated passenger and the man on the platform will, upon measuring, obtain the same value for the speed of light. Relativity also made it clear that the simple addition of speeds in the previous case follows from the fact that the speed of light vastly exceeds the speeds encountered in everyday life. The mathematical formalism of relativity based on the universal constancy of the speed of light intermingled space and time into a four-dimensional continuum making time a kind of fourth dimension. It is interesting to note that before Einstein the English historian and novelist H. G. Wells pictured time as the fourth dimension in his book "The Time Machine".

A stunning conclusion of relativity happened to be the derivation of the famous equation E = Mc2 which predicted that the matter in weighable objects can be converted into energy. Although one could argue that the tragedy of Hiroshima and Nagasaki was also a consequence of E = Mc2, the theory of relativity reshaped scientific thinking contributing tremendously to an upsurge of scientific and technological advances beginning with the first few decades of the last century. Relativity interpreted the gravitational force that attracts bodies to the earth as a warping of space-time by matter. Theory also provided a mathematical apparatus to describe the large-scale structure of the universe, its origin and its future in the light of observational results. The radicalism of relativity together with its logical consistency influenced epistemology.

Nobel Prize for Physics

In the speech presenting Einstein to the Royal Swedish Academy at the award of the 1921 Nobel Prize for Physics, Professor Savant Arrhenius (noted for being the first to recognize the possibility of global warming by an accumulation carbon dioxide) said "There is no physicist living today so widely known as Albert Einstein. Most discussion centers on his theory of relativity. This pertains essentially to epistemology and therefore has been the subject of lively debate in philosophical circles".

Relativity is no longer a highly abstract and arcane mathematical jargon of no relevance to everyday life. The precise measurements of distances on the earth's surface now use relativity. Global positioning systems (GPS) can locate positions on the surface of the earth to an accuracy of a meter. Airplanes, and even some motor cars, now have built-in GPS navigation systems. A GPS operates by an exchange of signals from a constellation of satellites and the distances are computed on the basis of time measurements. It takes into account the relativistic effects on time flow by the motion of the earth and its gravity. If the calculations were to be based on Newton's classical theory alone, the inaccuracies would be so great that the GPS system will simply not work.

Second paper

The photoelectric effect, the topic of Einstein's second 1905 paper, refers to the phenomenon of the detachment of electrons from a metal by light impinging on its surface. Einstein explained the mechanism of photoelectric emission, invoking the idea of light quanta introduced earlier by the German physicist Max Planck. When a blacksmith plunges a piece of iron into the fire it turns first red, then yellowish and bluish white as the temperature rises. How the intensities of light of different colors emanating from hot bodies change with temperature could not be explained on the basis of the cherished principles of nineteenth century classical physics which attributed a wave character to light, although the wave theory of light had been remarkably successful in understanding almost every other optical phenomenon known at that time. Max Planck worked out a formula accounting quantitatively for the intensities of heat radiation on the assumption that matter emits and absorbs light in packets of energy termed quanta. The premise Einstein took was to consider light as an entity intrinsically endowed with both particle and wave properties. This seemed too radical even to Max Planck who vehemently disagreed and went to the extent of not recommending Einstein to a position at the Prussian Academy of Sciences. Einstein's 'light particle' or the photon concept explained many other things besides the photoelectric effect. It became clear how light could induce chemical reactions giving important clues to the nature of the process by which green plants utilize sunlight for the synthesis of food. The color of a dyed fabric put in the sun for drying gradually fades and the extent of fading depends on the duration of exposure.

Photon hypothesis

This apparently trivial observation can be readily comprehended by Einstein's photon hypothesis as the destruction of dye molecules in the fabric by the 'bullets of light particles" but not by the wave theory of light. Einstein's explanation of the photoelectric effect was the seed for the development of the full-fledged theory of quantum mechanics developed subsequently by Erwin Schr"dinger, Werner Heisenberg and Paul Maurice Dirac. Quantum mechanics is undoubtedly a most successful scientific theory. It encompasses the behavior of molecules, atoms, nuclei, subatomic particles and the gross structure of matter. The success of a theory is determined not only by its ability to explain known things. It should also have a predictive power and an unambiguous prescription to work out foretelling. The experimental verification of predictions improves the credibility of a theory. To this date thousands of predictions of quantum mechanics have been verified and not a single one refuted. Is quantum mechanics only a high- brow theory of no relevance to the practicalities of mankind? Has it changed the underpinnings of our society by giving new tools and methods to promote the quality of life? Of many affirmative answers, just one example suffices to show what quantum mechanics has done. The comforts we enjoy today because of domestic electrical appliances, communication and transport systems, computers, medical diagnostic equipment etc. followed the invention and development of the transistor, an integral component of all the above devices. Transistors did not originate from empirical technology. Their design and development were heavily dependent on quantum mechanics, which accurately tells how electrons move about in solids.

Unmatched foresight

Einstein's third paper in the year 1905 on Brownian motion, was a derivation from the then existing classical physics. Yet, its far reaching conclusions demonstrated his unmatched foresight. In 1827 the botanist Robert Brown working as the clerk cum librarian to the Linnaean Society in London looked through his microscope and noted a persistent erratic motion of pollen grains suspended in water. Soon it became clear that this motion was not due to extraneous influences but resulted from an inherent thermal agitation of the molecules of the liquid. The liquid molecules constantly bombard the grain from all sides. If the grain is sufficiently small, the molecular hits it receives from one side overshoot those from the opposite side giving a net force pushing the particle. Einstein analyzed this problem mathematically and showed ways of obtaining molecular sizes and their numbers. In fact he demonstrated at the same time that molecules really exist. Jean-Baptiste Perrin, a French physicist at the Sorbonne and the Swedish chemist Theodor Svedberg extended Einstein's work on Brownian motion, enabling a wide range of practical applications in chemistry and medicine. These techniques are indispensable in modern medicine to obtain information about proteins, blood components, cancer cells, viruses etc.

Greatest minds in physics

The aspirations of the World Year of Physics go further than the centennial celebration of the genius of Albert Einstein who wrote three landmark papers in 1905. Lebohang Moleko, Ambassador of the Kingdom of Lesotho in presenting the draft resolution at the United Nations General Assembly to proclaim the World Year of Physics in 2005, made the following statement:

"The aim of this International Year goes beyond the mere celebration of one of the greatest minds in physics of the twentieth century. This year will provide the world with an opportunity for the largest possible audiences to acknowledge the progress and importance of this great field of science. One will remember that, for example, transistors, computers, lasers, and magnetic resonance imagery are direct products of the last decades of fundamental research in laboratories of physics, where tomorrow's materials and technologies of information are worked out today. We can stimulate the interest of young people to pursue scientific careers and to revive in them a taste for the scientific approach: this must be a national as well as a worldwide endeavor. It is indeed essential to understand that the twenty-first century will see an increasing need for the concepts and tools provided by the physical sciences in finding solutions to major problems which confront us such as energy production, environmental protection, and even public health". Mr. Moleko concluded his speech stating that the subject of physics had never been discussed previously in the United Nations Assembly and he considers it as an honour and privilege to have brought up this matter.

The World Year of Physics hopes to address the central issues that physics is confronted with. Undoubtedly, physics played a key role in achieving the present level of technological advancement. It provided tools and ideas to other scientific disciplines paving the way for discoveries of major economic significance. Recently, physics research has become more and more expensive, sometimes unaffordable even for the most affluent nations. As current knowledge stands we have two rigorous and separately self-consistent theories, quantum mechanics and the relativity theory of gravity. The problem is that these two theories are mutually incompatible. Attempts to fuse them have given rise to new speculative theories with various names such as strings, membranes and extra-dimensions. These potential fundamental theories of physics need to be verified or falsified by experiment in order to redirect thinking. Proposed experiments sometimes require several kilometer wide accelerator rings machined to millimeter accuracy, space probes or deep underground laboratories housing millions of tons of costly material. The progress of physics relies on the results of these crucial experiments.

A decline has also been noticed in the number of students taking up physics as a profession. One of the objectives of declaring 2005 as the World Year of Physics is for initiating programs to attract the most talented youth to science, physics in particular. Developed countries have heaped the fruits of physics to achieve economic affluence through advanced technology. In them, industries are tied to research in physics laboratories and physicists find employment not only in academia and national laboratories but in the industrial sector as well. A good example is the rapid evolution of passenger aircraft to near perfection. This spectacular engineering feat owes much more to physics than to any other field. Fluid mechanics, thermodynamics, quantum mechanics, materials physics, electromagnetism, optics and relativity have contributed to its design.

Developing countries and science

Developing countries in general have not fully recognized the potential of physics. The absence of a concerted effort to build self-reliance in research education and technology appears to have contributed more to this state of affairs than the paucity of resources. There seems to be a tendency in developing countries to regard science as 'foreign ' and to value it in the same way as foreign commodities in the market. The application of physics or any other branch of science does not entirely mean its direct adoption to gear technological advancement at the national level. It should be applied to one's thinking, to matters of everyday life and to the resolution of routine problems as well. Although the price of gas keeps on escalating, the physics-teacher/housewife rarely places the lid on the utensil and cuts down the gas flow once potatoes are boiling. Most developing countries entertain physics education mainly as a prerequisite for engineering, medicine and other technical and scientific disciplines.

The physics education programs of developing countries need to be strengthened and revived, not only to cater for the above requirement but also to produce physicists who could do frontier work in their home countries. Industries should promote their basic research with the involvement of physicists. It is also essential to initiate activities to arouse curiosity, sharpen the precision of thinking and remedy the undiscerning style of 'boiling potatoes". Developing countries also waste a great deal of time formulating policies that are rarely implemented but frequently amended. What they really require seems to be an environment conducive to research and bench work instead of discussions.