The lowest temperature possible is 0 Kelvin, but extremely low temperatures have been achieved using laser and evaporative cooling. MIT holds the current record at 450 pK. Sub-zero temperature research has been important in understanding physics and chemistry, and has helped with refrigeration.
The lowest possible temperature is 0 Kelvin (-459.67 °F, -273.15 °C), abbreviated 0 K. Although reaching exactly 0 K is thermodynamically impossible, extremely low temperatures have been achieved in the laboratory using a combination of laser cooling and evaporative cooling .
MIT holds the current record, 450 pK (petaKelvins), or 4.5×10-10 K, which was announced in September 2003. The Low Temperature Lab at Helsinki University of Technology has achieved a nuclear spin temperature of 100 pK , but this only affects the nuclear spin and not all thermodynamic degrees of freedom.
Science has been engaged in sub-zero temperature research primarily since the advent of modern refrigeration in the mid-19th century. It is thought that around 800 million years ago, most of the planet was covered in sub-zero temperatures, giving rise to a planetary ice cap sometimes called “Snowball Earth”. Until 10,000 years ago, a planetary ice age, known as the Wisconsin glaciation, was still in progress. This ice age may have prevented the rise of civilization. Its passage was followed by the Neolithic revolution and modern agriculture.
Here are some sub-zero temperatures and their relevance:
450 pK – lowest temperature achieved, by MIT, in 2003.
170 nK – first temperature at which a Bose-Einstein condenses, a unique state of matter in which a group of atoms collapses into the lowest quantum state of external potential, allowing quantum effects to be observed at the macroscopic level.
700 nK – former laboratory record temperature, from NIST, in 1994.
>li>0.95 K – melting point of helium.
1 K – the coldest known region of outer space, the Boomerang nebula.
2.17 K – temperature below which helium is in a superfluid state, demonstrating bizarre properties such as crawling out of a jar in which it is placed.
2.7 K – average temperature of outer space, the thermal echo of the Big Bang.
3 K – approximate temperature of typical liquid helium.
4.1 K – temperature at which superconductivity was first demonstrated, using mercury.
65 K – approximate temperature of liquid nitrogen.
123 K – informal boundary between cryogenics and refrigeration.
150 K – temperature of the hottest known superconductor, the compound SnBa4Tm4Cu6O18.
183.7 K – the coldest land temperature ever recorded, at Vostok, Antarctica.
273.15 K – melting point of water.
Subzero temperature research is an important part of science. Without sub-zero knowledge, we’d know a lot less about physics and chemistry, not to mention we’d have to eat our food pretty fast, before it starts rotting from lack of refrigeration!
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