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When applied to physical phenomena and bodies, the macroscopic scale describes things as a person can directly perceive them, without the aid of magnifying devices. This is in contrast to observations (microscopy) or theories (microphysics, statistical physics) of objects of geometric lengths smaller than perhaps some hundreds of micrometers.
A macroscopic view of a ball is just that: a ball. A microscopic view could reveal a thick round skin seemingly composed entirely of puckered cracks and fissures (as viewed through a microscope) or, further down in scale, a collection of molecules in a roughly spherical shape.
Classical mechanics may describe the interactions of the above-mentioned ball. It can be considered a mainly macroscopic theory. On the much smaller scale of atoms and molecules, classical mechanics may not apply, and the interactions of particles is then described by quantum mechanics. As another example, near the absolute minimum of temperature, the Bose–Einstein condensate exhibits elementary quantum effects on macroscopic scale.
The term "megascopic" is a synonym. No word exists that specifically refers to features commonly portrayed at reduced scales for better understanding, such as geographic areas or astronomical objects. "Macroscopic" may also refer to a "larger view", namely a view available only from a large perspective. A macroscopic position could be considered the "big picture".
- Reif, F. (1965). Fundamentals of Statistical and Thermal Physics (International student edition. ed.). Boston: McGraw-Hill. p. 2. ISBN 007-051800-9.
we shall call a system "macroscopic" (i.e., "large scale") when it is large enough to be visible in the ordinary sense (say greater than 1 micron, so that it can at least be observed with a microscope using ordinary light).