What is the coldest temperature ever achieved?

Answer 1

That would be absolute zero: 0 Kelvin or -273.15 Celsius. At close to absolute zero many interesting phenomena occur, i.e. atoms stop vibrating, substance combine to a super mass, electrons are no longer active in bonding (molecules are held together by merely London dispersion forces).

This is all theoretical. Absolute 0 has never been achieved by man. Some scientist think it may be impossible here on earth due to the fact that heat from the earth will always permeate even the thickest insulation. That being the case the coldest man has ever achieved is 4 Kelvin, or - 269.15 Celsius, or - 452.47 Fahrenheit. When trying to go colder than that the object being cooled would literally shatter into millions of pieces!

In an attempt to reach absolute zero, a piece of rhodium metal was super cooled to 100 picokelvin (1/10000000000 Kelvin) in 1999. That is the coldest temperature achieved by scientific means. The coldest natural temperature ever recorded was -89.2 OC in Antarctica 1983.

Answer 2

-43.15 oC