Quantum physics was invented at the beginning of the 20th century by young European physicists such as Einstein, Bohr and Schrödinger. The goal of quantum physics is to describe how really small objects behave. These small objects are on the scale of the nanometre (a billionth of a metre) and include atoms, electrons or photons (the particles which constitute light). Most people think quantum physics is hard to understand and is full of strange paradoxes. However, quantum physics actually deals with everyday life; it explains the colours of objects and their thermal, electric and chemical properties. This theory has also enabled the invention of many new and useful technologies including electronic transistors, lasers, medical imaging, etc…
Quantum physics forces us to change our point of view at an atomic level; for instance, an electron is both a particle and a wave. Its properties, such as its energy or its magnetization, are quantized : they cannot have the value they want anymore, like a car that could only go at particular speeds, such as 25 m/h, 50 m/h, and 100 m/h…
The measurement of a quantum object is also unusual because it has an effect on the measured object, and complies with the uncertainty principle. Finally, a quantum object, because it is also a wave, has strange properties, such as the tunnel effect.
Of course, these quantum singularities do not work on a larger scale, and neither a man nor a computer is a wave! However, in order to understand the properties of “big” objects, you often need to use quantum physics, especially as far as solids are concerned. This is the case for superconductors, which represent one of the most beautiful examples of a direct manifestation of quantum laws right in front of us.
