Absolute zero

Definition

Absolute zero is the theoretical lowest temperature possible, measured at 0 Kelvin (or -273.15 degrees Celsius and -459.67 degrees Fahrenheit). At this temperature, the motion of atoms theoretically comes to a complete stop, and the system possesses minimal energy, marking the point where entropy reaches its minimum value. This concept is crucial for understanding temperature, heat transfer, and the behavior of matter at extremely low temperatures.

5 Must Know Facts For Your Next Test

1. At absolute zero, the entropy of a perfect crystal is predicted to be zero according to the Third Law of Thermodynamics.
2. Achieving absolute zero is physically impossible, but scientists can get very close to it using advanced cooling techniques.
3. The concept of absolute zero plays a crucial role in cryogenics, which studies the behavior of materials at extremely low temperatures.
4. In practice, the lowest temperature ever achieved in a laboratory setting is about 500 picokelvins (pK), which is only a fraction above absolute zero.
5. Many quantum phenomena become observable near absolute zero, including Bose-Einstein condensation, where particles occupy the same quantum state.

Review Questions

• How does achieving temperatures close to absolute zero affect the properties of matter?
  • When matter is cooled to temperatures close to absolute zero, it exhibits unique quantum mechanical behaviors. At these low temperatures, atoms move very slowly and can even condense into states like Bose-Einstein condensates. In these states, particles behave as if they are a single quantum entity, showing properties that differ significantly from their behavior at higher temperatures.
• Discuss why absolute zero cannot be achieved in practice and what implications this has for scientific research.
  • Absolute zero cannot be achieved due to the Third Law of Thermodynamics, which states that as a system approaches absolute zero, the amount of energy required to remove additional heat increases infinitely. This limitation has significant implications for scientific research; while we can study behaviors and phenomena at extremely low temperatures, we can never fully explore the properties of matter at absolute zero. This gap drives innovation in experimental techniques and theories in physics.
• Evaluate how the concept of absolute zero relates to entropy and the behavior of systems at extremely low temperatures.
  • The concept of absolute zero is deeply intertwined with entropy; as systems cool down towards this temperature, their entropy approaches a minimum value. This reflects a state of perfect order where particle motion virtually ceases. Evaluating this relationship helps scientists understand phase transitions and thermodynamic principles. It also informs areas like cryogenics and quantum mechanics, where behaviors at low temperatures reveal new physics that challenge classical theories.

Related terms

Kelvin: The Kelvin scale is an absolute temperature scale where 0 K is defined as absolute zero, making it a critical scale for scientific measurements involving temperature.

Thermal Equilibrium: Thermal equilibrium refers to the state when two bodies in contact with each other reach the same temperature, resulting in no net heat transfer between them.

Entropy:

Entropy is a measure of disorder or randomness in a system, and at absolute zero, entropy reaches its minimum value, indicating perfect order.