Editing Macroscopic scale (section)

== Overview ==
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 [[length]]s smaller than perhaps some hundreds of [[micrometre]]s.

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 [[molecule]]s in a roughly [[sphere|spherical]] shape (as viewed through an [[electron microscope]]). An example of a physical theory that takes a deliberately macroscopic viewpoint is [[thermodynamics]]. An example of a topic that extends from macroscopic to microscopic viewpoints is [[histology]].

Not quite by the distinction between macroscopic and microscopic, [[Classical mechanics|classical]] and [[quantum mechanics]] are theories that are distinguished in a subtly different way.<ref>{{cite journal|last1=Jaeger|first1=Gregg|title=What in the (quantum) world is macroscopic?|journal=American Journal of Physics|date=September 2014|volume=82|issue=9|pages=896–905|doi=10.1119/1.4878358|bibcode = 2014AmJPh..82..896J }}</ref> At first glance one might think of them as differing simply in the size of objects that they describe, classical objects being considered far larger as to mass and geometrical size than quantal objects, for example a football versus a fine particle of dust. More refined consideration distinguishes classical and quantum mechanics on the basis that classical mechanics fails to recognize that matter and energy cannot be divided into infinitesimally small parcels, so that ultimately fine division reveals irreducibly granular features. The criterion of fineness is whether or not the interactions are described in terms of the [[Planck constant]]. Roughly speaking, classical mechanics considers particles in mathematically idealized terms even as fine as geometrical points with no magnitude, still having their finite masses. Classical mechanics also considers mathematically idealized extended materials as geometrically continuously substantial. Such idealizations are useful for most everyday calculations, but may fail entirely for molecules, atoms, photons, and other elementary particles (and vice versa). In many ways, classical mechanics can be considered a mainly macroscopic theory. On the much smaller scale of atoms and molecules, classical mechanics may fail, and the interactions of particles are then described by quantum mechanics. Near the [[Absolute zero|absolute minimum of temperature]], the [[Bose–Einstein condensate]] exhibits effects on macroscopic scale that demand description by quantum mechanics.

In the [[quantum measurement problem]] the issue of what constitutes macroscopic and what constitutes the quantum world is unresolved and possibly unsolvable. The related [[correspondence principle]] can be articulated thus: every macroscopic phenomena can be formulated as a problem in quantum theory. A violation of the correspondence principle would thus ensure an empirical distinction between the macroscopic and the quantum.

In [[pathology]], macroscopic diagnostics generally involves [[gross pathology]], in contrast to microscopic [[histopathology]].

The term "megascopic" is a synonym. "Macroscopic" may also refer to a "larger view", namely a view available only from a large perspective (a hypothetical [[Macroscope (science concept)|"macroscope"]]). A macroscopic position could be considered the "big picture".