Absolute Zero

Absolute zero is the holy grail of temperatures, but even though we know how cold it is -273.15 Degrees Celsius reaching it has eluded scientists for many years and probably will for many years to come.
The person who discovered this was Sir William Thomson who stated that heat is just molecules moving around in a substance. So he wanted to get stuff as cold as he could get it. Through this experiment he found out that all kinetic energy could be drained from an substance so it could no longer get any colder.

Absolute zero dose not mean a complete absence of motion in a substance instead it means the state of minimal movement of a substance's particles.