Model of a molecule, with coloured balls representing different atoms
Amodel is an informative representation of an object, person, or system. The term originally denoted theplans of a building in late 16th-century English, and derived viaFrench andItalian ultimately fromLatinmodulus,'a measure'.[1]
Inscholarly research andapplied science, a model should not be confused with atheory: while a model seeks only to represent reality with the purpose of better understanding or predicting the world, a theory is more ambitious in that it claims to be an explanation of reality.[4]
As a noun,model has specific meanings in certain fields, derived from its original meaning of "structuraldesign orlayout":
Model (art), a person posing for an artist, e.g. a 15th-century criminal representing the biblical Judas in Leonardo da Vinci's paintingThe Last Supper
Model (person), a person who serves as a template for others to copy, as in arole model, often in the context of advertising commercial products; e.g. the firstfashion model, Marie Vernet Worth in 1853, wife of designerCharles Frederick Worth.[5][6]
Model (organism) a non-human species that is studied to understand biological phenomena in other organisms, e.g. a guinea pig starved of vitamin C to study scurvy, an experiment that would be immoral to conduct on a person
Model (mimicry), a species that is mimicked by another species
Model (logic), a structure (a set of items, such as natural numbers 1, 2, 3,..., along with mathematical operations such as addition and multiplication, and relations, such as) that satisfies a given system ofaxioms (basic truisms), i.e. that satisfies the statements of a giventheory[7]
Model (CGI), a mathematical representation of any surface of an object in three dimensions via specialized software
Model (MVC), the information-representing internal component of a software, as distinct from its user interface
A physical model (most commonly referred to simply as a model but in this context distinguished from aconceptual model) is a smaller or larger physical representation of anobject, person orsystem. The object being modelled may be small (e.g., anatom) or large (e.g., theSolar System) or life-size (e.g., afashion model displaying clothes for similarly-built potential customers).
Thegeometry of the model and the object it represents are oftensimilar in the sense that one is arescaling of the other. However, in many cases the similarity is only approximate or even intentionally distorted. Sometimes thedistortion is systematic, e.g., a fixed scale horizontally and a larger fixed scale vertically when modellingtopography to enhance a region's mountains.
An architectural model permits visualization of internal relationships within the structure or external relationships of the structure to the environment. Another use is as atoy.
Instrumented physical models are an effective way of investigating fluid flows forengineering design. Physical models are often coupled withcomputational fluid dynamics models to optimize the design of equipment and processes. This includes external flow such as around buildings, vehicles, people, orhydraulic structures.Wind tunnel andwater tunnel testing is often used for these design efforts. Instrumented physical models can also examine internal flows, for the design of ductwork systems, pollution control equipment, food processing machines, and mixing vessels. Transparent flow models are used in this case to observe the detailed flow phenomenon. These models are scaled in terms of both geometry and important forces, for example, usingFroude number orReynolds number scaling (seeSimilitude). In the pre-computer era, the UK economy was modelled with the hydraulic modelMONIAC, to predict for example the effect of tax rises on employment.
Water-powered model of the UK economy –MONIAC in the Science Museum, London
Female model demonstratingbrassiere for similarly-built potential buyers
Weather models usedifferential equations based on the laws ofphysics, and a coordinate system which divides the planet into a 3D grid.
Aconceptual model is a theoretical representation of a system, e.g. aset of mathematical equations attempting to describe the workings of the atmosphere for the purpose of weather forecasting.[8] It consists ofconcepts used to help understand orsimulate a subject the model represents.
Abstract orconceptual models are central tophilosophy of science,[2][3] as almost everyscientific theory effectively embeds some kind of model of thephysical orhuman sphere. In some sense, a physical model "is always the reification of some conceptual model; the conceptual model is conceived ahead as the blueprint of the physical one", which is then constructed as conceived.[9] Thus, the term refers to models that are formed after a conceptualization or generalization process.[2][3]
Economic model, a theoretical construct representing economic processes
Language model, a probabilistic model of a natural language, used for speech recognition, language generation, and information retrieval
Large language models are artificial neural networks used for generative artificial intelligence (AI), e.g. ChatGPT
Mathematical model, a description of a system using mathematical concepts and language
Statistical model, a mathematical model that usually specifies the relationship between one or more random variables and other non-random variables
Model (CGI), a mathematical representation of any surface of an object in three dimensions via specialized software
Medical model, a proposed "set of procedures in which all doctors are trained"
Mental model, in psychology, an internal representation of external reality
Model (logic), a set along with a collection of finitary operations, and relations that are defined on it, satisfying a given collection of axioms
Model (MVC), information-representing component of a software, distinct from the user interface (the "view"), both linked by the "controller" component, in the context of the model–view–controller software design
Model act, a law drafted centrally to be disseminated and proposed for enactment in multiple independent legislatures
According toHerbert Stachowiak, a model is characterized by at least three properties:[10]
1. Mapping
A model always is a modelof something—it is an image or representation of some natural or artificial, existing or imagined original,[11] where this original itself could be a model.
2. Reduction
In general, a model will not include all attributes that describe the original but only those that appear relevant to the model's creator or user.
3. Pragmatism
A model does not relate unambiguously to its original. It is intended to work as a replacement for the original
a) for certain subjects(for whom?)
b) within a certain time range(when?)
c) restricted to certain conceptual or physical actions(what for?).
For example, a street map is a model of the actual streets in a city (mapping), showing the course of the streets while leaving out, say, traffic signs and road markings (reduction), made for pedestrians and vehicle drivers for the purpose of finding one's way in the city (pragmatism).
Additional properties have been proposed, likeextension anddistortion[12] as well asvalidity.[13] The American philosopher Michael Weisberg differentiates between concrete and mathematical models and proposes computer simulations (computational models) as their own class of models.[14]
According to Bruce Edmonds, there are at least 5 general uses for models:[15]
Prediction: reliably anticipating unknown data, including data within the domain of the training data (interpolation), and outside the domain (extrapolation)
Explanation: establishing plausible chains of causality by proposing mechanisms that can explain patterns seen in data
Theoretical exposition: discovering or proposing new hypotheses, or refuting existing hypotheses about the behaviour of the system being modelled
Description: representing important aspects of the system being modelled
Illustration: communicating an idea or explanation
^Thalheim:Towards a Theory of Conceptual Modelling. In:Journal of Universal Computer Science, vol. 16, 2010, no. 20, S. 3120
^Dietrich Dörner:Thought and Design – Research Strategies, Single-case Approach and Methods of Validation. In: E. Frankenberger et al. (eds.):Designers. The Key to Successful Product Development. Springer-Verlag, Berlin et al. 1998, S. 3–11.
^M. Weisberg:Simulation and Similarity - using models to understand the world. Oxford University Press, New York 2013
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Media related toPhysical models at Wikimedia Commons
