Definition

Noun: * Brownian motion: The random, erratic movement of microscopic particles suspended in a fluid (a liquid or a gas), caused by continuous bombardment from molecules of the surrounding fluid.

Usage

• Brownian motion is a fundamental concept in physics and chemistry that provides direct evidence for the existence of atoms and molecules.
• It is typically observed under a microscope.
• The term is used as a singular, uncountable noun.

Examples

• Under the microscope, the pollen grains exhibited constant Brownian motion.
• The phenomenon of Brownian motion was first systematically studied by Robert Brown in 1827.
• Einstein's 1905 paper provided a theoretical explanation for Brownian motion.

Advanced Usage

• Brownian motion is also a key concept in mathematical finance, where it is used to model the random walk of stock prices (often called a Wiener process).
• The adjective form is Brownian (e.g., Brownian movement, Brownian dynamics).

Variants and Related Words

• Brownian movement: A synonymous term for Brownian motion.
• Pedesis: A less common technical synonym.
• Random walk: A related mathematical model describing a path of successive random steps.

Synonyms

• Random motion
• Erratic movement
• Pedesis (technical)

Related Phrases and Concepts

• Diffusion: The net movement of particles from an area of high concentration to an area of low concentration, which is driven by a related random molecular process.
• Thermal motion: The random motion of molecules due to their thermal energy, which is the cause of Brownian motion.
• Stochastic process: A mathematical object defined by a collection of random variables, of which Brownian motion is a prime example.

Noun

1. the random motion of small particles suspended in a gas or liquid