Table of Contents
Temperatures above zero do go up to thousands and ten thousands degrees Celsius.
But this is not possible in the case of negative temperature in the Celsius scale.
There does exist a temperature limit when we keep on decreasing the temperature. Here’s why..
Temperature
Temperature is a well-known term used to specify how hot or cold something is.
At a microscopic or atomic level, temperature is directly related to the average kinetic energy of the constituent particles (atoms or molecules) of a substance.
Therefore, when saying that something is getting warmer or colder, we are essentially saying that the particles’ average kinetic energy is increasing or decreasing, respectively.
The Lowest Temperature Limit: Absolute Zero
There exists a fundamental limit for the coldness of matter. This limit is known as absolute zero, which is the zero point on the Kelvin scale (0 K).
The Kelvin scale is the standard SI unit of temperature. It relates to the Celsius scale by the formula: T(K) = t(C°) + 273.15. Hence, zero K is equivalent to -273.15°C.
Why is Absolute Zero the Coldest?
Since the temperature in the Kelvin scale is proportional to the average kinetic energy of the particles, if this average kinetic energy becomes zero, the temperature also becomes zero Kelvin .
Because kinetic energy, being proportional to the square of velocity (KE = ½mv²), cannot be a negative value, there can be no temperature lower than absolute zero.
In the classical view of physics, atoms at absolute zero would possess no kinetic energy and should completely cease all motion.
The Effect of Quantum Mechanics in Absolute Zero
However, when examining matter at the atomic and subatomic level, quantum mechanics must be taken into account, which modifies the classical view.
According to the Heisenberg Uncertainty Principle (specifically, the position-momentum uncertainty relation: ∆x.∆p ≥ h/4π where h is planck’s constant, it is impossible to know both the exact position and the exact momentum of a particle simultaneously.
Applying this to an atom confined in a space (like an atom in a crystal lattice), if the particle were to come to a complete stop (zero momentum), its position would become perfectly known. This violates the uncertainty principle.
This means that even at 0 K, the particles cannot be perfectly motionless; they must retain a small, irreducible amount of kinetic energy. This minimum, non-zero energy is known as the zero-point energy.
Why this temperature is unattainable
According to the laws of thermodynamics, reaching this temperature takes infinite steps and time.
Scientists have been trying rigorously to reach at least the nearest temperature to absolute zero. And have reached a temperature of 38 trillionths of a degree above absolute zero.
