German researchers approach absolute zero

Physicists at the University of Bremen, Germany have produced the lowest temperature ever recorded, at 38 picoKelvin, which is 38 trillionths of a degree above absolute zero.

Absolute zero is measured as -273.15 °C and it is the lowest possible temperature on the thermodynamic scale. It is impossible for an object to truly reach this temperature because there would have to be zero atomic motion or kinetic energy in its atoms. A team of physicists at the Centre for Applied Space Technology and Microgravity (ZARM) at the University of Bremen in Germany, has come very close to absolute zero by producing a temperature of 38 picoKelvin, or 38 trillionths of a degree above absolute zero.


While researching the wave properties of atoms, the team trapped a gas cloud composed of rubidium atoms in a magnetic field in a vacuum chamber. This gas cloud was then cooled down until it turned into a Bose-Einstein Condensate (BEC), a phenomenon in which atoms begin acting essentially like one big atom, allowing strange quantum effects to become visible to the naked eye. The researchers then dropped the BEC 120 meters down the ZARM Drop Tower. During the fall, they also switched the magnetic field containing the gas cloud on and off several times. The switching slows the expansion of the gas to an almost complete stop, greatly lowering its temperature due to the reduced molecular speed.


The researchers were only able to sustain the record-breaking temperature for two seconds. According to their simulations, this temperature could be maintained for about 17 seconds in a weightless environment such as the International Space Station.