This Is the Closest Scientists Have Gotten to Reaching Absolute Zero

The absolute temperature scale gives measurements in Kelvins-unlike Celsius and Fahrenheit, which use degrees. Absolute zero is thus 0 Kelvin, not 0 degrees Kelvin.

- CAROLINE DELBERT

RESEARCHERS FROM FOUR UNIVERSITIES in Germany have conditioned a lab to register the coldest effective temperature in a research-controlled environment ever recorded-38 trillionths of a Kelvin above absolute zero. According to a 2021 study published in the journal Physical Review Letters, the temperature persisted for two seconds at the University of Bremen's Center of Applied Space Technology and Microgravity (ZARM), and the conditions that made this possible could have longstanding ramifications for quantum mechanics.

Absolute zero is 0 Kelvin, equal to -273.15 degrees Celsius, or -459.67 degrees Fahrenheit. This is the point at which particles are essentially motionless, and it's the lowest possible temperature we could ever theoretically reach, according to the laws of thermodynamics. Some researchers seek absolute zero for use in precision instruments that can test the fundamental laws of physics, while others do so to model something called the Cold Big Bang, when all matter exploded into being and the universe began operating under observable laws of matter and energy. In this latter sense, looking at a system at absolute zero-one almost completely without kinetic energy-would be close to observing the very beginning of physics.