Scale of temperature the Swedish astronomer Anders Celsius (1701–1744), who developed a similar temperature scale two years before his death. The degree Celsius (°C) can refer to a specific temperature on the Celsius scale as well as a unit to indicate a temperature "interval "(a difference between two temperatures or an uncertainty). From 1744 until 1954, 0 °C was defined as the freezing point of water and 100 °C was defined as the boiling point of water, both at a pressure of one standard atmosphere. Although these defining correlations are commonly taught in schools today, by international agreement the unit "degree Celsius" and
Planck temperature its temperature. If an object were to reach the temperature of ("T"), the radiation it would emit would have a wavelength of (Planck length), at which point quantum gravitational effects become relevant. At temperatures greater than or equal to "T", current physical theory breaks down because we lack a theory of quantum gravity. Planck temperature Planck temperature, denoted by "T", is the unit of temperature in the system of natural units known as Planck units. It serves as the defining unit of the Planck temperature scale. In this scale the magnitude of the Planck temperature is equal to 1, while