Heike Kamerlingh Onnes (1853-1926)
Heike Kamerlingh Onnes was a Dutch physicist who first observed the phenomenon of superconductivity while carrying out pioneering work in the field of cryogenics. An important step on the way to this discovery was his success in producing liquid helium, a feat that enabled scientists to achieve colder experimental conditions than previously possible. Kamerlingh Onnes won the Nobel Prize in Physics in 1913 for his work with low temperatures that led to the liquefying of helium.
A native of Groningen, The Netherlands, Kamerlingh Onnes was born on September 21, 1853. His father owned a factory and helped instill a strong work ethic in his son. When he was 17, Kamerlingh Onnes enrolled at Groningen University. There he studied chemistry and physics, quickly distinguishing himself. In 1871, a treatise he composed on vapor density garnered first prize in a University of Utrecht competition; the next year he submitted an essay to a contest at the University of Groningen that received second prize. Also in 1871, the budding scientist traveled to Germany to study at the University of Heidelberg. There he gained a firm foundation in experimentation in the laboratory of renowned physicist Gustav Robert Kirchhoff, and had the further opportunity of studying with chemist Robert Wilhelm Bunsen.
Kamerlingh Onnes returned to The Netherlands in 1873 to begin work on a doctoral degree in physics at Groningen. He received it in 1879 following the defense of his thesis, which offered new theoretical and experimental evidence for the Earth’s rotation. Kamerlingh Onnes began an assistantship at Delft Polytechnic in 1878. Four years later the University of Leiden offered him a position as chair of the experimental physics department. The new post included directorship of the school’s physical laboratory, allowing Kamerlingh Onnes nearly complete freedom in his research. His interest in low-temperature physics inspired him to reorganize and reequip the lab to be a state-of-the-art center for cryogenic investigations. He considered cryogenics an important means of verifying J. D. Van der Waals' law of corresponding states, outlined in 1880, over as broad an array of temperatures as feasible.
For many years, Kamerlingh Onnes attempted to improve the cryogenic methods developed by other scientists, such as R. P. Pictet, Carl Linde and James Dewar. In 1906 he found a way to produce significant amounts of liquid hydrogen by building an advanced hydrogen-liquefaction machine. This achievement led, in 1908, to one of his key long-term goals, the liquefying of helium. His determined that the temperature of liquid helium was about -268.8 degrees Celsius, only a few degrees greater than absolute zero.
That incredibly cold temperature, which rightly gained the laboratory at Leiden the title “the coldest place on Earth," was not enough to satisfy Kamerlingh Onnes. He continued to look for better ways of achieving lower temperatures and hoped to solidify the liquid helium he produced. Years later, improved methodology enabled him to achieve cooling to nearly just one degree over absolute zero, but solid helium remained out of his reach. The person to finally accomplish the elusive deed, in 1926, was Willem Hendrik Keesom, who had studied under Kamerlingh Onnes and succeeded him as director of the Leiden physics lab, which came to be known as the Kamerlingh Onnes Laboratory.
With access to such incredibly cold temperatures, Kamerlingh Onnes and others who came to work or visit in his laboratory were able to carry out new kinds of experiments and observe behaviors of materials never seen before. In 1911, Kamerlingh Onnes found that as the temperature of certain conductors approaches absolute zero, the electrical resistance they normally exhibit suddenly disappeared. He dubbed the phenomenon, which he initially observed in mercury, “supraconductivity,” which later evolved into the term used today, “superconductivity.” Other scientists soon repeated Kamerlingh Onnes’ experiments with superconductivity and a new field of scientific investigation was born. Many decades passed before anyone developed a widely accepted theory to explain the experimental observations relating to superconductivity, and many aspects of superconductors are still actively researched today.
After a long and fruitful career, Kamerlingh Onnes retired from the University of Leiden in 1923. He fell ill in 1926 and died on February 21 of that year. Although the Nobel Prize may be considered his highest honor, his legacy can be found anywhere in the world where cryogenic investigations are carried out or superconductors are used. Kamerlingh Onnes received a wide variety of other prestigious awards and tributes, including the Rumford, Matteucci and Franklin medals, an honorary doctorate from the University of Berlin, honorary and foreign memberships into numerous scientific academies, and election into the Royal Academy of Sciences of Amsterdam. Moreover, Kamerlingh Onnes’ interest in finding ways that his cryogenic research could be put to practical use inspired him to co-found the International Institute of Refrigeration.