Glossary of Astronomical Terms/absolute zero
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Absolute zero is the point at which all molecular motion ceases, i.e, there is no heat energy present. It is referred to as a temperature of zero kelvins, -273.15 °C, or -459.67 °F. As certain pure metals and metallic alloys approach absolute zero, their resistance to electrical flow becomes negligible.
Absolute zero cannot be achieved experimentally, although it can be closely approached. The current record stands at less than 0.000000001 K. Our knowledge of conditions at absolute zero is therefore restricted to mathematical extrapolations1.
- Question for students: Under what conditions would you think absolute zero might actually exist in the universe?
1 An example of extrapolation would be: If we know that the brightness of a a light is x lumens when measured at a distance of 1 meter, and that it is x/4 lumens at 2 meters, we can extrapolate the brightness at, for example, 3.6 meters, 7,258,491.682 meters, or 0.0052 meter.
