coldest

Coldest is the superlative form of cold, describing the lowest temperature in a given set or comparison. It is used across contexts—from meteorology and geography to physics—with the sense that one item has less thermal energy than others.

Temperature is measured in several scales, most notably Celsius, Fahrenheit, and Kelvin. Absolute zero, defined as 0 kelvin, equals −273.15 °C or −459.67 °F and represents the theoretical limit of coldness; it cannot be reached in practice, though temperatures near it are routinely produced in laboratories.

Natural extremes on Earth: The coldest measured air temperature on the Earth's surface is −89.2 °C (−128.6 °F) at Vostok Station, Antarctica in 1983. Among inhabited places, Oymyakon and Verkhojansk in Siberia experience some of the coldest winters, with sustained winter temperatures down to about −50 to −60 °C.

Outer space and celestial environments contain much colder regions. The cosmic microwave background is about 2.7 kelvin. Some interstellar gas clouds and objects such as the Boomerang Nebula have temperatures around 1 kelvin, colder than the mean space between stars.

Laboratories have produced ultracold matter approaching absolute zero, with atomic gases cooled to nanokelvin and even picokelvin temperatures using laser cooling and evaporative cooling, enabling studies of quantum phenomena.