What is thermodynamic temperature?

Thermodynamic temperature, also called absolute temperature, measures temperature starting from absolute zero, where particles have minimal thermal motion. It is typically expressed using the kelvin scale and serves as a fundamental base quantity in physics and the International System of Units. Historically defined through thermodynamic work and heat transfer, it is now understood in relation to the kinetic energy of free particle motion.

What we know

• Thermodynamic temperature measures temperature starting from absolute zero, which is the point where particles possess minimal thermal motion. [1, 2]
• The unit of measurement for thermodynamic temperature is the kelvin, which shares the same interval size as the degree Celsius. [2, 5]
• Lord Kelvin historically defined thermodynamic temperature based on macroscopic relations between thermodynamic work and heat transfer. [2]
• Absolute zero cannot actually be reached experimentally, as recognized by the third law of thermodynamics. [4]

Still open

• While absolute zero is the lowest point on the standard thermodynamic temperature scale, negative absolute temperatures also exist under specific conditions and are technically hotter than any positive temperature.

Where to go next

• how it workedHow is absolute zero defined?
• compared withHow does the Celsius scale relate to the kelvin?
• what caused itWhat is the third law of thermodynamics?
• whoWho was Lord Kelvin?
• how we knowHow do thermometers measure kinetic energy?
• an unexpected connectionCan temperatures be negative and hotter than positive values?Although thermodynamic temperature begins at absolute zero, negative absolute temperatures are theoretically and experimentally possible and represent states hotter than any positive temperature.

Sources

• [1]thermodynamic temperature (Wikidata Q264647) · CC0 1.0
• [2]Thermodynamic temperature · CC BY-SA 4.0
• [3]Scale of temperature · CC BY-SA 4.0
• [4]Temperature · CC BY-SA 4.0
• [5]Celsius · CC BY-SA 4.0

Your path

1. What are the principles of statistical mechanics?
2. /What is thermodynamic temperature?