Scientists have been able to cool copper to 0.6% of a degree
Celsius from absolute zero. Ever closer, never there.
The increments of the Kelvin scale are equal to the Celsius
degree. A footnote to the Kelvin scale is the Rankin scale,
proposed by William John Macquorn Rankine in 1859. It is an
absolute scale like the Kelvin scale, but whose increments are
equal to the Fahrenheit degree.
See also in The book of science:
Readings on wikipedia: