All molecular motion stops at absolute zero, which is 0 Kelvin (K), -273.15 degrees Celsius (°C), or -459.67 degrees Fahrenheit (°F). At this temperature, the molecules of a substance have the minimum possible kinetic energy, effectively ceasing all motion.
Absolute zero is a theoretical concept because, in practice, it is impossible to reach this temperature. The laws of thermodynamics state that as a system approaches absolute zero, the energy required to remove heat from the system increases exponentially. This makes it practically unattainable.
In summary, while absolute zero represents the point at which molecular motion would theoretically stop, it remains a theoretical limit rather than an achievable temperature.