The medium used in slowing light by a factor of 20 million was a cluster of atoms called a "Bose-Einstein condensate" chilled to a temperature of roughly 50-billionths of a degree above absolute zero (that's zero on the Kelvin scale
), far colder than the depths space, and was then coupled with a brief pulse of tuned laser light.
It is called absolute zero and the scale most often used is the Kelvin scale
, which is the Celsius scale shifted by approximately 273[degrees].
Coaxing a gas to a negative temperature on the Kelvin scale
has produced, paradoxically, the hottest temperature ever measured.
Quiz of the Day ANSWERS: 1 A hand-blown glass for ale or wine; 2 The Kelvin scale
; 3 The Yangtze; 4 The halibut; 5 London Bridge; 6 Gary; 7 Deadly nightshade; 8 Atlanta, 1996; 9 The harvesting of the first wheat; 10 The Carry On films.
Kelvin:The metric unit of temperature comes from the Kelvin scale
named after the Scottish physicist William Kelvin who was a professor at Glasgow university.