As an object or substance gets colder, its molecules slow down. Theoretically, the lowest temperature an object can reach is called absolute zero. That's about -460°F, or -273°C. At absolute zero, all molecular motion in an object would freeze to a halt, and the object would contain no heat energy. It is physically impossible to reach absolute zero, but scientists have gotten very close to it with the help of special refrigeration devices and techniques. What is absolute zero? A the temperature at which water freezes B the lowest temperature ever reached on Earth C the highest temperature an object or substance can reach before boiling D the temperature an object would be if its molecules were completely still BACK