Kelvin Celsius, which has the same magnitude. The definition implies that absolute zero (0 K) is equivalent to . In 1848, William Thomson, who later was made Lord Kelvin, wrote in his paper, "On an Absolute Thermometric Scale", of the need for a scale whereby "infinite cold" (absolute zero) was the scale's null point, and which used the degree Celsius for its unit increment. Kelvin calculated that absolute zero was equivalent to −273 °C on the air thermometers of the time. This absolute scale is known today as the Kelvin thermodynamic temperature scale. Kelvin's value of "−273" was the negative reciprocal
Thermodynamic temperature wavelength increases (the photons' energy decreases). When the particles of a substance are as close as possible to complete rest and retain only ZPE-induced quantum mechanical motion, the substance is at the temperature of absolute zero ("T"=0). Note that whereas absolute zero is the point of zero thermodynamic temperature and is also the point at which the particle constituents of matter have minimal motion, absolute zero is not necessarily the point at which a substance contains zero thermal energy; one must be very precise with what one means by "internal energy". Often, all the phase changes that "can" occur in