Absolute zero

CelsiusKelvin

Bose Einstein condensate

Robert Boyle 0001

Leiden - Kamerlingh Onnes Building - Commemorative plaque

Boomerang nebula

Absolute zero is the lowest possible temperature where nothing could be colder and no heat energy remains in a substance. It is the point at which the fundamental particles of nature have minimal vibrational motion, retaining only quantum mechanical, zero-point energy-induced particle motion. Absolute zero is quantitatively defined as 0 Kelvin (K), which translates to -273.15 degrees Celsius (°C) or -459.67 degrees Fahrenheit (°F).

Definition and Scale

The concept of absolute zero is a critical element in the thermodynamics field, particularly in the study of the kinetic theory of gases. According to this theory, the temperature of a gas is proportional to the average kinetic energy of its particles. As the temperature decreases, the particles move more slowly. At absolute zero, the particles would theoretically stop moving entirely, although quantum mechanical effects provide a lower limit to this activity.

The Kelvin scale, a thermodynamic temperature scale, starts at absolute zero. Unlike the Celsius and Fahrenheit scales, where temperatures can go below zero, the Kelvin scale establishes absolute zero as its null point, making it a natural choice for scientific purposes.

Physical Implications

Reaching absolute zero is a physical impossibility due to the Third law of thermodynamics, which states that the entropy (or disorder) of a perfect crystal approaches zero as the temperature approaches absolute zero. In practical terms, this law implies that it is impossible to remove all energy from a substance.

Experiments have brought materials to temperatures very close to absolute zero, where they exhibit remarkable properties such as superconductivity and superfluidity. Superconductivity occurs when a material conducts electricity without resistance, often near absolute zero. Superfluidity is a phase of matter that occurs at very low temperatures, characterized by the absence of viscosity.

Historical Context

The concept of absolute zero was first developed in the 19th century by physicists including Lord Kelvin (William Thomson), after whom the Kelvin temperature scale is named. The pursuit to reach temperatures as close as possible to absolute zero has led to numerous scientific breakthroughs and the development of new fields of research, such as cryogenics.

Modern Applications

Today, research and technology that operate at or near absolute zero temperatures are crucial in various scientific fields. Examples include the study of quantum mechanics, where researchers can observe the quantum behavior of atoms more clearly at extremely low temperatures, and in the development of quantum computers. Additionally, MRI machines, a common tool in medical diagnostics, rely on superconducting magnets that operate at temperatures close to absolute zero.

See Also

• Thermodynamics
• Kelvin
• Cryogenics
• Superconductivity
• Superfluidity