Quips, Quotes and Quanta

The following sections are included:

• Preface

• Contents

In 1875 when the seventeen-year old, Max Planck (1858 – 1947), applied to Professor Gustav Kirchhoff (1824 – 1887) of the University of Berlin to study physics with him, the eminent professor told him quite frankly, “Why do you want to come into physics? All is done and understood.” Since Planck did not think he had enough talent for his other choice, a career in music, he went against the professor's advice and continued with physics…

As the end of the nineteenth century approached, physicists could be justifiably proud of their science. It seemed that they had found the theories necessary to explain all physical phenomena. On Friday, April 30, 1897, a couple of years after Planck commenced his studies at the University of Berlin, the great British physicist, Sir Joseph John Thomson (1856 – 1940), announced to the regular evening meeting of the Royal Institute that he had discovered a particle smaller than an atom. Considering the fact that the very existence of atoms was still a controversial topic, this announcement was such a fantastic event that one of the prominent colleagues present thought it was a hoax. JJ, as Thomson was known, was not surprised at that reaction since he himself had found his discovery difficult to accept…

Scientific revolutions are much like political revolutions. During their initial phases they are ignored by almost everyone except the revolutionary activists and their conservative opposition. It is only when the revolution is full-blown or almost over that the rest of the world takes notice. Thus, it was at the beginning of the twentieth century in physics. There were flaws in the existing science, but most physicists could ignore them since there were really only the three flaws mentioned earlier, and these were rather esoteric little flaws. Similarly, there were flaws (social injustices) in many countries, but people could also ignore these. In both cases the revolutions that ensued left the world forever changed…

No scientific idea has so captured mankind's imagination and interest as Einstein's General Theory of Relativity even though there seem to be no technological developments that have emerged from this work. It is an idea so beautiful that like any great work of art it can be appreciated for its own sake. It is an idea that has totally changed our view of the universe. After Einstein's annus mirabilis of 1905, he was already famous as one of the great scientists of the day…

High in the Caucasus, chained to a rock, until rescued by Hercules, lay the titan Prometheus. A vulture pecked at his liver to maintain and increase his agony. That is how Greek legend portrayed the punishment of the giver of fire. The gods were so jealous of the power of fire that they devised this torture for the immortal that gave man this gift. The legend shows that the Greeks understood well the might of fire, so well in fact, that they viewed fire as a gift stolen from the gods. Mankind has never lost this fascination with fire. From our brutish first ancestors, who must have approached the dancing flames with reverence and trepidation, to modern young lovers cuddling in front of a fireplace, fire has retained its magic…

The glow of neon lights is a familiar sight in our cities. They tell us where to EAT or which HONEST car or furniture dealer to buy from. They are a part of the very fabric of our society. Perhaps that is why we do not really see them and marvel at their colours. Yet, it is a very interesting phenomenon, this glow of neon lights and the colours they display. Why does the gas in such a tube glow when a current passes through it? Why is the colour of a given gas always the same? This is not the glow of a heated body like the glow of the filament of an incandescent light bulb; it is something totally different. Just how different the two phenomena are is most readily seen by passing the light from a light bulb and from a discharge tube through a prism. The light from the filament produces a more or less continuous spectrum like a rainbow. On closer inspection a few dark lines appear in the spectrum. On the other hand, the light from a discharge tube produces a series of very distinct bright lines of brilliantly pure colours. These colours are more characteristic of the gas in the tube than fingerprints are for an individual person…

Some of Bohr's results had actually been foreshadowed by Arnold Johannes Wilhelm Sommerfeld (1868 – 1951). Here was a man totally committed to science. Just prior to the appearance of Einstein's paper on Special Relativity, he had finished some outstanding work on the electrodynamics of electrons in motion. He had even considered electrons moving at speeds greater than light. When Einstein's paper on special relativity appeared and showed that this was not possible for electrons in empty space, Sommerfeld abandoned his work and turned to relativity…

At the beginning of the twentieth century, physicists again learned to view optical theory in an earlier light. In the seventeenth century Newton asserted that light was corpuscular or particle-like in nature. A century and a half later the work of luminaries like Thomas Young (1773 – 1829) and Augustin Jean Fresnel (1788 – 1827) definitely showed that, contrary to Newton's view, light was wave-like and not corpuscular, or particle-like, in nature. By passing light through a slit they demonstrated that light was diffracted just like a sound wave or water wave. It was only the very short wavelengths of visible light that had made it appear to travel like a particle in a straight line without spreading. This viewpoint was about to be reversed…

Unlike Planck's original idea of a quarter of a century earlier, de Broglie's ideas had an almost immediate impact. The most lasting of these occurred in Zürich, Switzerland and the resultant tremors spread across the physics world…

The years 1925 – 1927 became known among physicists as Knabenphysik (boys' physics) since all the creators of quantum mechanics, with the exception of Born and Schrödinger, were in their early twenties. These young men were: Heisenberg, Dirac, Jordan, and Pauli…

The essence of matrix mechanics was soon distilled by Max Born (1882 – 1970), Pascual Jordan (1902 – 1980), and Werner Heisenberg. Born's birthplace was what was then the Prussian (Silesian) city of Breslau (now Wroclaw). While he was still a small boy, his mother died and so his main influences, while growing up, were his father and his classmates. His father had done research in embryology and the mechanics of evolution. His classmates, Otto Töplitz and Ernst Hellinger, later became famous mathematicians…

Shortly after Heisenberg's return from Heligoland where he had come up with the first results in the direction of matrix mechanics, he was invited to lecture to the Kapitza Club at the Cavendish Laboratory in Cambridge. The title of his talk was Term Zoology and Zeeman Botany. At the end of his talk he briey mentioned his new results on matrix mechanics. In the audience was another young physicist, Paul Adrien Maurice Dirac (1902 – 1984) who, although this work should have been of extreme interest to him, paid no attention to it. As Dirac himself later explained, the seminars at the Cavendish Laboratory were held at two o'clock in the afternoon. “After a good lunch, this time was more suitable for a snooze than concentrated attention on a speaker.”…

Shortly after the completion of matrix mechanics, Schrödinger in the sequence of events already discussed, produced his wave theory. It was as different as could be from the matrix theory. Matrix mechanics dealt exclusively with discrete, discontinuous quantities whereas wave mechanics dealt with waves, which are intrinsically continuous. For this reason most physicists, steeped in their classical traditions and conservative by nature, found Schrödinger's theory more appealing…

The beautiful patterns of the spectra of atoms that led Bohr to his model and eventually Schrödinger to his equation and quantum mechanics still had one more surprise. Actually this goes back to 1896 when Pieter Zeeman (1865 – 1943) at the University of Leyden approached his boss, the famous Heike Kammerlingh Onnes (1853 – 1926), to study the spectral lines of atoms that were placed in a strong magnetic field. He was looking for an effect first studied without success by the great Michael Faraday (1791 – 1867), namely the effect of a magnetic field on light. He believed that if Faraday had thought the attempt worthwhile then it should be done with the better equipment available to him…

The following sections are included:

• Index