In 1911, a physicist cooled mercury and found something about electricity that changed modern physics

It is believed that the discovery of superconductivity was made by a Dutch physicist, Heike Kamerlingh Onnes, back in 1911. At that time, the scientist was conducting several experiments in his laboratory in the Netherlands and found something that no one had ever seen before. It turned out that when mercury was cooled to about 4.2 kelvin, it completely lost its electrical resistance.The phenomenon that first seemed like a laboratory curiosity later became the basis of superconductivity, i.e., the ability of electricity to move without any losses. Superconductivity research started with Onnes' experiment with liquid mercury, and since then, this scientific field has been developing actively, as evidenced by several historical analyses.Why was Onnes interested in extreme cooling?First, it should be noted that Onnes was already known for his achievements in the study of low-temperature physics. He conducted experiments in his laboratory in the Netherlands, which aimed to achieve near-zero temperatures.Superconductivity was not his goal in particular. He wanted to investigate the behaviour of matter at very low temperatures. In the course of his experiments, he cooled mercury and measured the electrical resistance.According to a peer-reviewed article published in Philosophical Transactions of the Royal Society A, it turned out that the absence of resistance occurred unexpectedly while doing so. It is significant to know that resistance was supposed to drop progressively in the scientific community rather than disappear entirely.When resistance disappearedResistance in regular cables is the reason why some of the energy is lost as heat. There is always a loss of some energy due to resistance in regular electric devices. However, mercury showed a unique reaction when Onnes conducted his experiment on it. The moment when mercury was chilled to a temperature below 4.2 kelvin, the resistance vanished suddenly.The National Institute of Standards and Technology (NIST) states that it was the moment that marked the discovery of superconductivity. They say that it became clear that it was possible to achieve a perfect current transmission without losses.Why superconductivity was influentialIt provided a whole new dimension of scientific problems that physicists needed to solve. They had to find out what made the matter become able to enter into such an interesting state as zero electrical resistance.It was quickly understood that this phenomenon was necessary for the creation of various technologies requiring powerful magnetic fields and extremely effective electric circuits. With time, the study of superconductivity became crucial for the creation of such things as MRI devices and particle accelerators.Even modern publications refer to Onnes's experiment in 1911 as the historical beginning of superconductivity studies. This demonstrates just how relevant the discovery remains more than a century after it was made.An accidental discovery based on preparationsSuperconductivity is often regarded as an accidental discovery. Yet, there was much more behind it than mere chance. Onnes had constructed an excellent laboratory and invented the technique of cooling. Years of research on low temperatures preceded the discovery.Sometimes, scientists use another term for such an invention: "serendipity with preparation." In other words, a prepared mind of a scientist observes something extraordinary and recognises its significance.According to Philosophical Transactions, the development of superconductivity was a result of an elaborate scientific program dedicated to the exploration of the physics of super-low temperatures. Without such preparation, the scientist would most likely have dismissed this peculiar behaviour of mercury.Why do physicists keep mentioning the 1911 experiment?Almost a century after Onnes' experiment, scientists still refer to it because it transformed physicists' perceptions of matter altogether. Until 1911, low temperatures were only considered as an experimental problem. After the discovery, physicists started to see super-low temperatures as a key to a whole new realm of physics.Moreover, this phenomenon showed scientists that even well-known substances could act unpredictably in specific conditions, which affected many areas of modern physics, including quantum mechanics and electronics.This story is worth remembering simply due to its simplicity. All that took place in the course of studying one material and using one piece of equipment.