Absorption has a number of meanings:

• In physics, absorption is a process in which particles of some sort encounter another material and are taken up by or even disappear in it. Specifically, it can refer to:

• Volume absorption of particles of gas or liquid in liquid or solid material is studied in physical chemistry.
• In optics absorption refers to the absorption of photons by a material.
• In acoustics absorption refers to the absorption of sound waves by a material.

• In economics, absorption refers to the total demand of an economy for goods and services both from within and without the economy.

Absorption should not be confused with adsorption, the formation of a liquid or gas film on a solid surface. Since antiquity, people have tried to understand the behavior of matter: why unsupported objects drop to the ground, why different materials have different properties, and so forth. ... Absorption, in chemistry, is a physical or chemical phenomenon or a process in which atoms, molecules, or ions enter some bulk phase - gas, liquid or solid material. ... A gas is one of the phases of matter. ... A liquid will assume the shape of its container. ... A solid is a phase of matter, characterized by resistance to deformation and changes of volume. ... Physical Chemistry is the combined science of physics, chemistry, thermodynamics, and quantum mechanics which functions to provide molecular-level interpretations of observed macroscopic phenomena. ... Optics (appearance or look in ancient Greek) is a branch of physics that describes the behavior and properties of light and the interaction of light with matter. ... Absorption, in optics, is the process by which the energy of a photon is taken up by another entity, for example, by an atom whose valence electrons make a transition between two electronic energy levels. ... For the Science Fiction weapon, as seen in Star Trek, see Photon torpedo. ... Acoustics is a branch of physics and is the study of sound, mechanical waves in gases, liquids, and solids. ... A schematic representation of hearing. ... U.S. Economic Calendar Economics at the Open Directory Project Economics textbooks on Wikibooks The Economists Economics A-Z Institutions and organizations Bureau of Labor Statistics - from the American Labor Department Center for Economic and Policy Research (USA) National Bureau of Economic Research (USA) - Economics material from the organization... In chemistry, adsorption of a substance is its concentration on a particular surface. ...