100 years ago, the emergence of quantum mechanics

Hidden Figures of the Standard Model and the New Quantum Mechanics: The Higgs Boson, Gravity, and the Atom

The high point of the research programme was the meeting that will be held this year. The goal of that work was to establish the contribution of a group of scientists, many of whom have not been acknowledged in the history of the field.

The standard model was successful in finding the linchpin elementary particle, the Higgs boson. The nature of the ‘darkmatter’, which seems to greatly outweigh conventional, visible matter in the wider cosmos, is one of the unexplained phenomena that comes from the fact that these extensions are on less-solid theoretical ground. Moreover, one important phenomenon, gravity, still resists being quantized.

The quantum revolution has brought some things, but still has work to do. The study of electromagnetism, states of matter and quantum mechanics have been reconstructed from the foundations of quantum mechanics. The original quantum theory doesn’t cover objects that move at close to light speed. These efforts drastically expanded the scope of quantum science and led researchers to develop the standard model of particles and fields, a process that finally came together in the 1970s.

These “hidden figures” include Lucy Mensing, who was a member of the same group as Heisenberg and worked out some of the first applications of his quantum-mechanical theory, says Daniela Monaldi, a historian at York University in Toronto, Canada. The publication of a biographical volume of essays on 16 of them will be one of the most notable events of the year.

A paper by Heisenberg was a bold attempt to solve the problem of figuring out how the light is absorbed by atoms. The idea of the atom was developed in the 1910s by the two physicists, who named it the ‘Sommerfeld model of the atom’. This model was a centrepiece of what has become known as the old quantum theory, which itself was the product of a realization at the turn of the twentieth century that the precepts of classical physics were not sufficient to explain observations of subatomic phenomena. There was a possibility that the gap could be closed by assuming the energy came from quanta.

The change in perspective of physics one century ago was just as consequential as the theory of evolution by natural selection is for biology.

This was a strategy born more out of desperation than from any philosophical conviction. Heisenberg said that it was sensible to not look at hitherto unobservable quantities like the position and period of the electron because of the complex nature of dealing with atoms with several electrons.

The definition of a classical system includes a set of rules for selecting allowable circles for electrons to travel around a nucleus. The model had successfully explained the spectrum of the hydrogen atom — consisting of just one proton and one electron — and the splitting of spectral lines in the presence of an applied electric field (the Stark effect) or magnetic field (the ordinary Zeeman effect). But it had run into a host of problems in dealing with hydrogen molecules, and with atoms with more than one electron.