A chunk of copper became the coldest cubic meter (35.3 cubic feet) on Earth when researchers chilled it to 6 millikelvins, or six-thousandths of a degree above absolute zero (0 Kelvin). This is the closest a substance of this mass and volume has ever come to absolute zero. Researchers put the 880-lb. (400 kilograms) copper cube inside a container called a cryostat that is specially designed to keep items extremely cold. This is the first cryostat built that is capable of keeping substances so close to absolute zero.