Absolute zero is defined as the lowest theoretically attainable temperature, where the particles of a substance would have the minimum possible energy. It is denoted as 0 Kelvin (K), which is equivalent to -273.15 degrees Celsius or -459.67 degrees Fahrenheit.
The reason why there is no exact value for absolute zero is rooted in the principles of thermodynamics and the behavior of matter at extremely low temperatures. Absolute zero represents a state of complete absence of thermal energy, where the motion of particles ceases. However, achieving this state is not practically achievable.
According to the third law of thermodynamics, it is impossible to reach absolute zero through a finite number of processes. As a system approaches absolute zero, the rate at which it loses heat and approaches perfect order becomes increasingly slow. This is due to the fact that as the temperature drops, materials and systems exhibit various quantum mechanical effects and behavior, such as quantum tunneling and the formation of Bose-Einstein condensates.
Quantum mechanics, which describes the behavior of particles at the atomic and subatomic level, introduces uncertainty and limits our ability to precisely measure or define certain properties. At temperatures approaching absolute zero, quantum effects become increasingly significant, making it impossible to precisely determine the state of a system or the temperature of absolute zero.
Additionally, the concept of absolute zero assumes an idealized system with no interactions or external influences. In reality, factors such as residual heat, imperfections in materials, and the presence of cosmic microwave background radiation prevent a system from reaching absolute zero.
While scientists can approach extremely low temperatures and reach fractions of a degree above absolute zero, achieving an exact value of 0 Kelvin is not feasible due to the fundamental limitations imposed by the laws of thermodynamics and quantum mechanics.