Lowest observed temperatures
The average background temperature of the Universe today is 2.73 Kelvin, but it has spatial fluctuations. For example, the
Boomerang Nebula has been spraying out gas at a speed of 500,000 km/h (over 300,000 mph) for the last 1,500 years. That has cooled it down to 1 K, as deduced by astronomical observation. This might be the lowest natural temperature recorded.
Much lower temperatures, however, can be achieved in the laboratory. The current (May 2009) world record was set in 1999 at 100 picokelvin by cooling a piece of
rhodium metal.
http://en.wikipedia.org/wiki/Absolut...d_temperatures
World record in low temperatures
Researchers of the YKI-group of the Low Temperature Laboratory have recently achieved the lowest temperature ever produced.
The record-low temperature was reached in a piece of rhodium metal, which was cooled to 100 pK, or 0.000 000 000 1 degrees above the absolute zero. Absolute zero is the limit of all temperatures, —273.15... C, a temperature one can never reach.
http://ltl.tkk.fi/wiki/LTL/World_rec...w_temperatures