6History of Cryogenics
Cryogenics was first invented in 1877 when some scientists found a way to cool and make oxygen turn into a liquid at extremely low temperatures, around 90 Kelvin or minus 183 degrees Celsius. Since then, the development of cryogenic theory has been associated with the progress in the capability of refrigeration devices. In 1895, it became possible to reach as low temperatures as 40 Kelvin. This allowed air to be liquified and separated into main elements. In 1908, helium could be liquified at 4.2 Kelvin. Just a few years later, scientists discovered a phenomenon called superconductivity, which refers to the propensity of supercooled metals to lose resistance to electricity. By the 20s and 30s of the 19th century, it was possible to reach close-to-absolute-zero temperatures. And around 1960, labs would generate temperatures of 0.000001 K or a millionth of one degree Kelvin above absolute zero. [6]
