<P> With a better theoretical understanding of absolute zero, scientists were eager to reach this temperature in the lab . By 1845, Michael Faraday had managed to liquefy most gases then known to exist, and reached a new record for lowest temperatures by reaching − 130 ° C (− 202 ° F; 143 K). Faraday believed that certain gases, such as oxygen, nitrogen, and hydrogen, were permanent gases and could not be liquified . Decades later, in 1873 Dutch theoretical scientist Johannes Diderik van der Waals demonstrated that these gases could be liquefied, but only under conditions of very high pressure and very low temperatures . In 1877, Louis Paul Cailletet in France and Raoul Pictet in Switzerland succeeded in producing the first droplets of liquid air − 195 ° C (− 319.0 ° F; 78.1 K). This was followed in 1883 by the production of liquid oxygen − 218 ° C (− 360.4 ° F; 55.1 K) by the Polish professors Zygmunt Wróblewski and Karol Olszewski . </P> <P> Scottish chemist and physicist James Dewar and the Dutch physicist Heike Kamerlingh Onnes took on the challenge to liquefy the remaining gases hydrogen and helium . In 1898, after 20 years of effort, Dewar was first to liquefy hydrogen, reaching a new low temperature record of − 252 ° C (− 421.6 ° F; 21.1 K). However Onnes, his rival, was the first to liquefy helium, in 1908, using several precooling stages and the Hampson--Linde cycle . He lowered the temperature to the boiling point of helium − 269 ° C (− 452.20 ° F; 4.15 K). By reducing the pressure of the liquid helium he achieved an even lower temperature, near 1.5 K. These were the coldest temperatures achieved on earth at the time and his achievement earned him the Nobel Prize in 1913 . Onnes would continue to study the properties of materials at temperatures near absolute zero, describing superconductivity and superfluids for the first time . </P> <P> The average temperature of the universe today is approximately 2.73 kelvins (− 270.42 ° C; − 454.76 ° F), based on measurements of cosmic microwave background radiation . </P> <P> Absolute zero cannot be achieved, although it is possible to reach temperatures close to it through the use of cryocoolers, dilution refrigerators, and nuclear adiabatic demagnetization . The use of laser cooling has produced temperatures less than a billionth of a kelvin . At very low temperatures in the vicinity of absolute zero, matter exhibits many unusual properties, including superconductivity, superfluidity, and Bose--Einstein condensation . To study such phenomena, scientists have worked to obtain even lower temperatures . </P>

What's the difference between zero and absolute zero