— temperature, measured in absolute thermodynamic scale, independent of the thermometric substance properties (see temperature scale). Measured from absolute zero. The unit of absolute temperature in SI — kelvin.

Error in measurement, expressed in terms of the value measured. Absolute error is determined by the difference between the measurement result and the actual value of a physical quantity (com. Relative error).

— changing light visible position on the celestial sphere, finitude is due to the speed of light and movement of the observer and a result movement of the Earth in outer space. There are age aberration of light,caused by the motion of the Solar system in the Galaxy, year — movement of the Earth in its orbit around the Sun, the daily — the actual rotation of the Earth. Most significant in size — annual aberration of light, discovered in $1725$ by the English scientist James Bradlyeyem $(1693-1762)$.

— the origin of the absolute temperature; is at $273.16$ K below the triple point of water. Temperature equal to absolute zero, characterizes the ground state of many-particle systems, ie the state with the lowest possible energy (see zero energy), in which atoms and molecules is carried out so-called «zero» oscillations. At absolute zero all substances other than helium are solid crystalline state. From Ernst theorem implies that, in practice, absolute zero is unattainable.

— distortion in optical systems,caused by the use of broad beam and use non-monochromatic light. Manifest that image in some cases is not fully clear, exactly matching object or are painted. By aberrational optical systems include astigmatism, distortion, coma, spherical aberration, chromatic aberration.