Tempertaures in both Celsius and Fahrenheit scales can be negative. Why is a negative tempertaure impossible on the absolute scale?
Zero degrees on the absolute scale is defined as the temperature with minimum possible energy associated with motion of elementary particles (atoms and molecules). Such a temperature can never be negative.
The absolute temperature scale, also known as the Kelvin scale, does not allow for negative temperatures because it is based on the concept of absolute zero. Absolute zero, which is 0 Kelvin (K), is the lowest possible temperature where the particles of matter have minimal or no energy. In other words, it is the point at which all molecular motion ceases.
In contrast, the Celsius and Fahrenheit scales are based on the freezing and boiling points of water, which are arbitrary reference points. In these scales, negative temperatures are possible because they are relative to these reference points.
Absolute zero is equivalent to -273.15 degrees Celsius, or -459.67 degrees Fahrenheit. Since there is no temperature below absolute zero, negative temperatures are not possible on the absolute temperature scale.
To understand why negative temperatures are not possible on the absolute scale, we need to introduce the concept of absolute zero. The absolute scale, also known as the Kelvin scale, is based on the Kelvin temperature unit (K).
Absolute zero is defined as the lowest possible temperature and corresponds to zero Kelvin (0 K). At this temperature, the particles in a substance would have minimal thermal energy, and all molecular motion would cease. It is regarded as the point where thermal energy cannot be further removed from a system.
In contrast, both the Celsius and Fahrenheit scales can have negative temperatures. Negative temperatures on these scales indicate temperatures below their respective freezing points (0 degrees Celsius and 32 degrees Fahrenheit). These negative temperatures are still valid because they are relative to the freezing point of water or some other arbitrary reference point.
On the Kelvin scale, however, temperatures cannot be negative because it is an absolute scale with zero Kelvin as its starting point. The Kelvin scale only measures temperatures above absolute zero, with increasing values representing increasing thermal energy. Therefore, negative temperatures are not possible on the absolute scale because they would imply a lower energy state than absolute zero, which is not feasible based on our current understanding of thermodynamics.