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Heike Kamerlingh Onnes

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Heike Kamerlingh Onnes was a pioneering Dutch experimental physicist. He is best known for his groundbreaking research into extremely low temperatures. This specific field of science is known as cryogenics.

Leiden - Kamerlingh Onnes Building - Commemorative plaque
Leiden - Kamerlingh Onnes Building - Commemorative plaque

His work allowed scientists to explore how matter behaves when it is near absolute zero. By studying these extreme conditions, he unlocked secrets about gases and electricity. His discoveries changed the way we understand the physical properties of the universe.

In 1908, Onnes achieved a major scientific milestone by liquefying helium. To reach such extreme cold, he utilized several pre-cooling stages. He employed the Hampson–Linde cycle, which is a process used to produce liquid gases. This cycle relies on the Joule–Thomson effect to lower temperatures.

He first cooled the gas to the boiling point of helium, which is -269 °C or 4.2 K. By then reducing the pressure of the liquid helium, he reached nearly 1.5 K. At that time, this was the lowest temperature ever recorded on Earth.

To conduct this research, Onnes required large amounts of helium. He obtained the gas through specific industrial processes. In 1911, he sourced helium from Welsbach's company. This company processed a mineral called thorianite to produce thorium for gas mantles. Helium was produced as a side product of this work. Previously, Onnes had obtained helium by processing monazite. He would trade the processed monazite, which still contained thorium, to acquire the helium. On Earth, helium is usually found alongside radioactive material because it is a product of radioactive decay.

Onnes's most famous discovery occurred in 1911 during experiments with electrical conductivity. He was investigating how electricity moves through pure metals like mercury, tin, and lead. At the time, there was a scientific debate about what would happen at absolute zero. Some scientists, including Lord Kelvin, believed electrical resistance would become infinitely large. They thought electrons would simply stop moving. However, Onnes believed that electrical resistance would steadily decrease. On 8 April 1911, he proved his theory correct.

While using a solid mercury wire immersed in liquid helium, he found that resistance suddenly vanished at 4.2 K. He called this new state superconductivity.

During these same experiments, Onnes observed another strange phenomenon. Just before reaching approximately 1.8 K, he noticed the boiling of the helium bath suddenly stopped. Instead, the liquid visibly shrank through a process of evaporation. This was the first observation of superfluidity. This discovery added to our understanding of how fluids behave in extreme cold. His work in 1911 provided a deep look into the different states of matter. These observations helped define the boundaries of modern low-temperature physics.

Kamerlingh Onnes had a distinguished academic career. He was born on 21 September 1853 in Groningen, Netherlands. He studied at the University of Groningen and the University of Heidelberg. In 1879, he earned his Ph.D. with a thesis regarding the Earth's rotation. In 1882, he became a Professor of Experimental Physics and Meteorology at Leiden University. He held this position until 1923. In 1904, he founded a massive cryogenics laboratory in Leiden. This facility became a central hub for researchers worldwide. It is now known as the Kamerlingh Onnes Laboratory.

His contributions earned him the highest honors in science. In 1913, he was awarded the Nobel Prize in Physics. The Nobel Committee recognized his investigations into the properties of matter at low temperatures. This work specifically led to the production of liquid helium.

His legacy continues through various scientific honors. There is a crater on the Moon named after him. The Kamerlingh Onnes Award and the Kamerlingh Onnes Prize were also established to recognize advances in low-temperature science. His original laboratory building in Leiden now serves as the university's Law Faculty. You can still see his scientific instruments at the Museum Boerhaave.

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