Nobel Physics Timeline Trivia Quiz

The first Nobel Prize in Physics was awarded to William Röntgen for his discovery of what he called X-rays, which are known in some countries as Röntgen rays. They are a type of electromagnetic radiation with a frequency smaller than that of visible light, as well as the range commonly called ultraviolet (UV) rays. This makes it possible for them to penetrate some materials that are opaque to visible light - hence their widespread use in medicine. They have a much wider range of practical and theoretical applications, due to their ionizing properties.

In November of 1985, Wilhelm Röntgen (1845-1923) decided to explore the previously noticed unidentified radiation produced by a piece of equipment known as a Crookes tube, used to explore streams of electrons called cathode rays. He published an article in the December issue of the journal of the Physical-Medical Society in the city of Würzburg (where he was working at the university, using the letter X for them, since they were previously unknown. An image of his wife's hand produced when it was placed between an X-ray source and a photographic plate made it immediately clear that there would be significant practical applications. Doctors around the world started to devise equipment to produce X-rays and record the images. Röntgen considered this so important for mankind that he never took out a patent on his theoretical or practical work.

Antoine Henri Becquerel shared the 1903 award with Pierre and Marie Curie. His citation referred to the discovery, theirs was for subsequent research on radioactivity. Becquerel had been investigating phosphorescence (the phenomenon in which an object absorbs light of one color, then emits light of another color) since his doctoral research, and was inspired by the work of Röntgen to look for a connection between X-rays and phosphorescence. He ultimately realised that in some cases the material itself (uranium in the first instance) did not need an external light source to produce penetrating X-ray-like radiation, but emitted it spontaneously.

It is interesting to note that this phenomenon had been observed in the 1860s by Abel Niépce de Saint-Victor, who had communicated it to Edmond Becquerel (Henri's father), who noted it in a book published in 1868. However, no further investigation was made by either of them.

While most people immediately think of the theory of relativity when the name Albert Einstein (1879-1955) is mentioned, it was his work in explaining the photoelectric effect that was the immediate reason for the Nobel Prize in Physics. (At that time, there had been no experimental confirmation of the predictions of special relativity, so it was considered speculative.) The citation read, a bit more fully, "for his services to theoretical physics, and especially for his discovery of the law of the photoelectric effect", referring to the emission of electrons from a material after light hits it. The problem was that the electrons' properties and behavior were inconsistent with that predicted by classical electromagnetic theory. Einstein came up with an explanation: light is not a wave, but a series of wave-packets, called photons. These behave like waves under some conditions and like particles at other times. Wave-particle duality is one of the fundamental concepts in the development of quantum mechanics.

Nobel Prizes are often awarded well after the work that produced them, generally because it takes time for the significance to become clear. In 1905, Einstein produce four groundbreaking papers in the scientific journal 'Annalen der Physik'. The first paper dealt with the photoelectric effect; the second explained Brownian motion and was instrumental in gaining general acceptance of the atom; the third introduced the theory of special relativity, and the fourth produced the famous mass-energy equivalence equation E=mc^2.

The full citation for Ernest Lawrence (1901-1958) in 1939 included reference to the important applications of this particle accelerator, including the development of artificial radioactive elements. Because of its circular shape, the particles could be accelerated multiple times, making it possible to give them higher energies than were previously possible. Lawrence (1901-1958) developed his cyclotron in 1930-31, and patented it in 1932. Although the synchrotron, developed in the 1950s, is even more effective, cyclotrons are still widely used in the production of radionuclides for medicine, and for research that does not require the full power of the (more complex and expensive) synchrotron.

In 1936 the Lawrence Radiation Laboratory became an official department of the University of California. The research they conducted concentrated on medical applications (because there was more money available for that than for pure physics research), and their efforts for make bigger and better cyclotrons actually kept them from coming up with some of the significant discoveries that were made by others using the same apparatus. However, during World War II Lawrence was able to develop a process for enriching uranium in his cyclotron that was instrumental in the Manhattan Project. When he received his Nobel medal (at a ceremony held at Berkely, due to World War II), fellow physicist Robert Wood wrote him a letter that included, "As you are laying the foundations for the cataclysmic explosion of uranium ... I'm sure old Nobel would approve." (The passage is excerpted from Gregg Herken's 2002 book 'Brotherhood of the Bomb: The Tangled Lives and Loyalties of Robert Oppenheimer, Ernest Lawrence, and Edward Teller'.)

Wolfgang Pauli (1900-1958) was nominated for a Nobel Prize by Albert Einstein for his establishment of the concept of spin in explaining the structure of matter. Einstein had been very impressed by a monograph Pauli published in 1926 exploring the theory of relativity (a work which is still considered authoritative on the subject). Pauli actually published relatively little for someone who had such a profound impact in physics, expounding most of his ideas in correspondence with the other theoretical physicists involved in the development of quantum mechanics and our understanding of the atom.

The first statement of the Pauli Exclusion Principle, in 1925, applied to electrons only; it was expanded in 1940 to include all fermions (a type of subatomic particle, worthy of a quiz on their own to explore them). As it is relevant to a high-school level understanding of atomic structure, it explains why electrons come in pairs (one spin up, one spin down) in each orbital of an atom, and explains why some numbers of electrons (2, 8, 18, and the others in the group now called Noble Gases, then referred to as Inert Gases) produce very stable atoms.

Hideki Yukawa (1907-1981) was the first Japanese winner of a Nobel Prize, awarded for his theory of mesons, a class of subatomic particles composed of quarks and antiquarks which is responsible for a number of nuclear interactions. Most specifically, a kind of meson called the pi meson (or ion) provides the so-called strong force, the glue that holds the protons and neutrons together in a nucleus, despite the very large repulsive force acting between protons (since they have the same charge). This was predicted by Yukawa in 1934, and the actual discovery of a pion in 1947 led to a whole new field of experimentation to explore the nature and properties of various kinds of meson.

All mesons are now considered to be made up of one quark and one antiquark (for more on this, look ahead to the next question). The different types of quark that combine produce different mesons.

In other words, Murray Gell-Mann (1929-2019) developed the Eightfold Way, a scheme for classifying hadrons (subatomic particles) according to their properties. This includes baryons (particles such as the proton and neutron which interact via the strong nuclear force), mesons, and leptons (particles such as the electron, which have a half-integral spin and are not involved with the strong force). The first version of this scheme was published in 1961, and has been expanded since.

To explain the symmetry of his hadron classification, Gell-Mann introduced the idea that they were composed of even more fundamental particles he called quarks (a word he borrowed from James Joyce). A proton, for example, is made from two up quarks and one down quark, while a neutron is composed of two down quarks and one up quark. An explanation of how quarks combine requires the introduction of such interesting terms to describe them as charm, color and strangeness.

Ernst Ruska (1906-1988) built the first electron microscope in 1933, while still working on his doctorate, half a century before the Nobel committee recognised him for that and the rest of the research he undertook in the field of electron optics. He realised that electrons, having an associated wave function with an extremely short wavelength, could be used to produce images of objects thousands of times smaller than could be investigated using light waves. While his was not the first microscope to be built on this principle, it was the first to achieve better resolution than could be obtained using light. Unlike many of the physicists in this quiz, he was not responsible for theoretical insight, but for the tenacity to produce a practical application of the theoretical concept for which Louis de Broglie won the Nobel Prize in Physics in 1929.

The 1986 prize was split between Ruska and the team of Gerd Binnig and Heinrich Rohrer, who designed the scanning tunneling microscope in 1981.

Frederick Reines (1918-1998) and Martin Lewis Perl (1927-2014) shared the 1995 award, but were given separate citations, since they worked independently in the same general area, and both made significant discoveries. Both citations included "for pioneering experimental contributions to lepton physics"; Reines's specified the discovery of the neutrino, while Perl's mentioned the discovery of the tau lepton.

If you recall the Eightfold way classification scheme developed by Murray Gell-Mann, one of the groups is called leptons. The first known, and most familiar, of these is the electron. Like other charged leptons, they can react with other particles to form larger particles, such as atoms. Uncharged leptons, which also have a half-integer spin, do not react with other particles. this obviously makes them extremely hard to detect! The neutrino is one example of an uncharged lepton. Their existence was first suggested by Wolfgang Pauli in 1930, to explain some unexpected observations related to beta decay. Their existence was proved in 1956 by Clyde Cowan and Frederick Reines. Because Cowan died in 1974, he was not included in the citation for this feat, since Nobel Prizes are not awarded posthumously, even if they are often decades after the work.

The Standard Model of the atom, developed through the 20th century, describes all particles as belonging to families with three generations, all of which share common electric and strong force interactions, but differ in mass and flavour. (No, you don't need to taste them, this is just the term chosen to describe their quantum numbers.) First generation leptons are the electron and the electron neutrino, the one Reines and Cowan detected. Second generation leptons are the muon (like a heavier electron) and the muon neutrino; third generation leptons are the tau (even heavier) and the tau neutrino. It was the detection of the tau during the 1970s by a research team at Stanford and the Lawrence Berkely National Laboratory that was mentioned in the citation for Perl.

Sir Roger Penrose (1931- ) shared the 1920 award with Reinhard Genzel and Andrea Ghez, who had jointly established the presence of a supermassive black hole at the centre of the Milky Way Galaxy. Black holes were clearly the theme of the year. Penrose, who started as a mathematician, was responsible for many significant theoretical contributions to cosmology, starting with his 1965 paper "Gravitational Collapse and Space-Time Singularities". This led to a collaboration with Stephen Hawking that produced the Penrose-Hawking singularity theorems mentioned in his citation.

Penrose's contribution to cosmology has continued in a number of areas, relating to the Big Bang, and to the unification of quantum theory and general relativity. On a different note, in the 1950s he and his father developed a sketch of a shape they called the Penrose Triangle (look it up), which looks like three rectangular bars joined in a triangle. But they cannot possibly be constructed, the is a trick of shading to produce the illusion. They also produced an impossible staircase (independently of the concept developed in the 1930s by Oscar Reutersvärd), a set of four staircases connected around the top of four walls in such a way that one can keep walking forwards and upwards around the whole path and arrive back at the starting point. If this sounds familiar, it may be because the Penroses sent the article in which they published the diagram to MC Escher, whose earlier work had inspired them to investigate impossible objects. Escher used the idea for one of his most famous lithographs, 'Ascending and Descending'.