Final answer:
Absolute zero is the theoretical temperature where all molecular motion stops, equivalent to 0 Kelvin or -273.15℃. The Kelvin scale is used in scientific settings and temperatures are expressed in kelvins, not degrees, directly relating to a substance's average kinetic energy.
Step-by-step explanation:
Absolute Zero and the Kelvin Temperature Scale
Absolute zero is the temperature at which all molecular motion ceases. This is considered the lowest possible temperature where no energy can be extracted as heat. The Kelvin scale, named after Scottish physicist Lord Kelvin, is the temperature scale used to measure from this point of no thermal motion. A temperature of 0 Kelvin (0 K) is equivalent to -273.15℃ and is the theoretical point of absolute zero. Unlike other temperature scales like Celsius or Fahrenheit, the Kelvin scale does not use the term 'degrees,' simply referring to kelvins.
The Kelvin scale is pivotal in scientific research due to its absolute nature. Because it starts at absolute zero, all temperatures on this scale are positive, making it very useful for scientific work, especially in fields like astronomy. The Kelvin scale is directly proportional to the average kinetic energy of particles, meaning that as the Kelvin temperature increases, so does the molecular motion and thus the energy of the system.
While absolute zero can't actually be reached, in laboratory settings, scientists have managed to cool samples to temperatures very close to it, around 1 x 10-10 K, showcasing the advancement of cooling techniques and the study of thermodynamics.