The Kelvin scale
The zeros of the Celsius and Fahrenheit scales were chosen by the people who made them. Later, the British scientist Lord Kelvin showed that there is a lowest temperature any object can have: absolute zero.
Figure to be added
Temperature measures the particles' kinetic energy, so as it falls the temperature falls. When every particle's kinetic energy is zero the object is at absolute zero, and no temperature can be lower. On the Celsius scale it is −273.15 °C.
The Kelvin scale
Its zero, 0 K, is absolute zero, and one kelvin is the same size as one degree Celsius. Ice melts at 273.15 K and water boils at 373.15 K — about 273 K and 373 K.
The international unit of temperature is the kelvin (K).
Who made the scales
- The Fahrenheit scale: Gabriel Fahrenheit (1686–1736)
- The Celsius scale: Anders Celsius (1701–1744)
- The Kelvin scale: Lord Kelvin (1824–1907)
- The clinical thermometer: Clifford Allbutt (1836–1925)