Related Experiment Video
Updated: Feb 12, 2026
10:13
Hemi-laryngeal Setup for Studying Vocal Fold Vibration in Three Dimensions
Published on: November 25, 2017
11.5K
Observing brownian motion in vibration-fluidized granular matter.
1Institut de Physique de la Matière Complexe, Faculté des Sciences de Base, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland. gianfranco.danna@epfl.ch
Nature
|August 22, 2003
Summary
Researchers explored non-equilibrium systems using a torsion oscillator in vibro-fluidized granular matter. Surprisingly, this system, analogous to Brownian motion, satisfied a fluctuation-dissipation relation, acting like a thermal bath.
Area of Science:
- Statistical Mechanics
- Granular Physics
- Non-Equilibrium Systems
Background:
- Brownian motion in gases led to equilibrium statistical mechanics concepts like viscosity and temperature.
- The Langevin model and fluctuation-dissipation theorem describe these equilibrium phenomena.
- Extending these ideas to non-equilibrium systems remains an open question.
Purpose of the Study:
- To investigate if equilibrium statistical mechanics formalisms can describe driven, non-equilibrium granular systems.
- To experimentally probe a vibro-fluidized granular medium as an analogue to a thermal bath for an immersed oscillator.
Main Methods:
- An experiment using a sensitive torsion oscillator immersed in a granular system fluidized by external vibrations.
- Measurement of noise and susceptibility of the oscillator.
- Analysis using concepts from equilibrium statistical mechanics.
Main Results:
- The vibro-fluidized granular medium, despite being a driven non-equilibrium system, can be approximated by equilibrium formalisms.
- Experimental access to granular viscosity and an effective temperature was achieved.
- These granular properties were found to be anisotropic and inhomogeneous.
- The granular system surprisingly satisfied a fluctuation-dissipation relation.
Conclusions:
- Equilibrium statistical mechanics concepts, including the fluctuation-dissipation theorem, can be extended to describe certain non-equilibrium granular systems.
- Vibro-fluidized granular matter can act as an effective 'thermal' bath.
- This provides a new experimental avenue for studying non-equilibrium phenomena and their relation to equilibrium concepts.
Related Concept Videos
02:49Classifying Matter by State
104.6K
Chemistry is the study of matter and the changes it undergoes. Matter is anything that has mass and occupies space. Matter is all around us; the air, water, soil, mountains, even our bodies are all examples of matter. Matter is divided into three states — solid, liquid, and gas — that are commonly found on earth. The fourth state of matter, plasma, occurs naturally in the interiors of stars.
104.6K
02:57Physical and Chemical Properties of Matter
167.1K
The characteristics that enable us to distinguish one substance from another are called properties.
167.1K
03:35Classifying Matter by Composition
91.5K
Matter: Pure Substances and Mixtures
According to its composition, the matter can be classified into two broad categories — pure substances and mixtures.
A pure substance is a form of matter that has a constant composition throughout with uniform properties. For example, any sample of sucrose has the same composition and same physical properties, such as melting point, color, and sweetness, regardless of the source from which it is isolated.
A mixture is composed of two or...
According to its composition, the matter can be classified into two broad categories — pure substances and mixtures.
A pure substance is a form of matter that has a constant composition throughout with uniform properties. For example, any sample of sucrose has the same composition and same physical properties, such as melting point, color, and sweetness, regardless of the source from which it is isolated.
A mixture is composed of two or...
91.5K
02:59The Atomic Theory of Matter
130.2K
The earliest recorded discussion of the basic structure of matter comes from ancient Greek philosophers. Leucippus and Democritus argued that all matter was composed of small, finite particles that they called atomos, meaning “indivisible.” Later, Aristotle and others came to the conclusion that matter consisted of various combinations of the four “elements” — fire, earth, air, and water — and could be infinitely divided. Interestingly, these philosophers...
130.2K
01:13What is Matter?
103.8K
The substance of the universe—from a grain of sand to a star—is called matter. Scientists define matter as anything that occupies space and has mass. An object’s mass and its weight are related concepts, but not quite the same. An object’s mass is the amount of matter contained in the object and is the same whether that object is on Earth or in the zero-gravity environment of outer space. An object’s weight, on the other hand, is its mass as affected by the pull of...
103.8K
01:19Vibrating Concrete
407
Mechanical vibrators are instrumental in compacting newly poured concrete within formwork and around reinforcements. This process is essential to eliminate trapped air pockets and establish a dense concrete mass. One widely used method is vibrating by internal vibrators, often referred to as a poker vibrator or immersion vibrator. It is rapidly inserted through the full depth of the freshly laid concrete and slightly extends into the layer below it (which remains in a plastic state). Consistent...
407