In theory, absolute zero is the temperature where the particles of matter stop moving. Absolute zero is impossible to achieve, because all particles move, even if it is just a small vibration. Some people have created temperatures very close to absolute zero, but the record temperature was 100 pK (Picokelvin) above absolute zero. Even getting close to absolute zero is difficult because anything that touches an object being cooled near absolute zero would give heat to the objects. Scientists use lasers to slow atoms when cooling objects to very low temperatures.
The Kelvin and Rankine temperature scales are defined so that absolute zero is 0 kelvins (K) or 0 degrees Rankine (°R). The Celsius and Fahrenheit scales are defined so that absolute zero is −273.15 °C or −459.67 °F.
At this stage the pressure of the particles is zero. If we plot a graph to it, we can see that the temperature of the particles is zero. The temperature cannot go down any further. Also, the particles cannot move in "reverse" either because as the movement of particles is vibration, vibrating in reverse would be nothing but simply vibrating again. The closer the temperature of an object gets to absolute zero, the less resistive the material is to electricity therefore it will conduct electricity almost perfectly, with no measurable resistance.
The Third Law of Thermodynamics says that nothing can ever have a temperature of absolute zero.
The Second Law of Thermodynamics says that all engines that are powered by heat (like car engines and steam train engines) must release waste heat and can not be 100% efficient. This is because the efficiency (percent of energy the engine uses up that is actually used to do the engine's job) is 100%×(1-Toutside/Tinside), which only is 100% if the outside temperature is absolute zero which it can not be. So, an engine can not be 100% efficient, but you can make its efficiency closer to 100% by making the inside temperature hotter and/or the outside temperature colder.
In September 2013, MIT scientists cooled a sodium gas to the lowest temperature ever recorded -- only half-a-billionth of a degree above absolute zero.
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| Absolute zero is defined to be −273.15°C, or 0 K. |
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