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Developments in modern physics

This very short overview of one century of modern physics is very incomplete, and does not even have the intention to be complete. It is merely an attempt to illustrate the aforementioned theory of the three A’s by means of the exciting science of modern physics.


At the end of the nineteenth century, the German physicist Max Planck must have been somehow attracted to the futile attempts of Rayleigh, Jeans and Wien to describe wavelength- and temperature-dependency of blackbody radiation. Not only this unexplainable phenomenon was a real challenge for physicists at the edge of the twentieth century, there were many more. Roentgen found out about some radiation he called X-rays, there was the mystery of fluorescence, Pierre and Marie Curie were concerned with alpha-, beta- and gamma-rays, not to forget the invariance of the speed of light. In the subsequent years, the amazement of many scientists all over the world led to insights that would have far-reaching consequences. It definitely was an exciting time to be alive.


Turning back to Max Planck now. In our story of modern physics, he is the man representing the transition from amazement to abstraction. In his quest for the answer on the nature of blackbody radiation, he came up with a daring idea. What if energy consists of discrete packets of energy, rather than being a perfectly continuous quantity? More people must have had this idea, but it was Planck who elaborated this theory in great detail. Doing so, this German scientist turned the amazement about blackbody radiation into an abstract theory of discrete electronic states, rightfully attributing him a physical constant and the 1918 Nobel Prize in Physics.


This theory of quantized energy led to a whole lot of discoveries never seen before. Not only did it lead to fundamental insights, for instance in the finestructure of atoms, the wave-like nature of mass and the mass-like nature of waves or even in the origin of the universe itself. It also led to applications we cannot imagine to live without these days. In 1958, Jack Kilby was the first one to make an integrated circuit (IC) and to prove its proper working. The theory behind these IC’s is based on the atomic structure and properties of semiconducting materials, a theory provided thanks to the understanding of the finestructure of atoms. From the one came the other, and now, 50 years after Kilby’s experiments, IC’s have led to an explosion of applications, one of which is the computer.