In physics, absolute zero is the coldest temperature that is theoretically possible. It is reached when the molecular movement of a substance virtually ceases and the lowest level of energy is reached, in other words absolute zero is a state in which the particles of a substance have no kinetic (movement) energy at all, meaning that there is no heat. Because particles cannot have less kinetic energy than zero this is theoretically the coldest possible temperature. Absolute zero measures –273.15° on the Celsius scale and –459.67° on the Fahrenheit scale.
By international agreement, absolute zero is defined as precisely; 0 K on the Kelvin scale, which is a thermodynamic (absolute) temperature scale; and –273.15 degrees Celsius on the Celsius scale. While scientists can not fully achieve a state of “zero” heat energy in a substance, they have made great advancements in achieving temperatures ever closer to absolute zero. They've also noticed that matter (especially metal) begins to behave in peculiar ways as you approach absolute zero.