Dutch physicist Heike Kamerlingh Onnes discovers superconductivity.

Superconductivity is a phenomenon that occurs when certain materials are cooled to extremely low temperatures, usually near absolute zero (-273.15°C or -459.67°F). At this temperature, some materials lose all electrical resistance and can conduct electricity with almost no energy loss, leading to zero electrical resistance and an ideal conductor.

The discovery of superconductivity dates back to 1911 when a Dutch physicist, Heike Kamerlingh Onnes, discovered that the electrical resistance of mercury drops to zero at a temperature close to absolute zero. Since then, many other materials have been found to exhibit superconductivity, including metals, alloys, and some ceramics.

The phenomenon is explained by the behavior of the electrons in the superconductor. When the material is cooled below its critical temperature, the electrons form pairs called Cooper pairs, which can move through the material without any resistance. This is because the pairs are held together by a kind of attractive force that results from the interaction between the electrons and the atoms of the material.

Superconductivity has many practical applications, such as in the construction of powerful magnets used in medical imaging, particle accelerators, and magnetic levitation trains. However, the need for extreme cooling has limited the practicality of superconductors in everyday use, although research continues to develop materials that exhibit superconductivity at higher temperatures.