In terminology, metaphor is transference of the relation between one set of objects to another set for the purpose of brief explanation; a compressed simile or one thing conceived as representing another. [1] A metaphor is nearly a perfect synonym of analogy, although there seem to be subtle differences.

Overview
In the 1980s, George Lakoff published a number of thermal word analyzing books. [7]

Scientific metaphor
A scientific metaphor is the use of metaphor in specialist scientific discourse. [2] An example of a scientific metaphor is transference of one established scientific relation between one set of object, e.g. heat generated in an atomic system, to another set, e.g. heat generated between people in a large metropolis, for the purpose of brief explanation. Other examples might include: the “feeling of electricity between people”, animal heat, the term relationship chemistry, etc. Scientific metaphors and scientific analogies often provoke heated debate, over whether or not the metaphor is an actual true statement of reality.

Thermodynamic metaphor
In human thermodynamics, metaphors are often used as testing ground terms to ferret out a theoretical insight. Whether or not the metaphor is correct is a matter specific to each thermodynamic metaphor. [3] The following is an example perspective, from Internet writer Frank Steiger, of a common metaphor usage in religious thermodynamics: [4]

Creationism would replace mathematics with metaphors. Metaphors may or may not serve to illustrate a fact, but they are not the fact itself. One thing is certain: metaphors are completely useless when it comes to the thermodynamics of calculating the efficiency of a heat engine, or the entropy change of free expansion of a gas, or the power required to operate a compressor. This can only be done with mathematics, not metaphors. Creationists have created a "voodoo" thermodynamics based solely on metaphors. This in order to convince those not familiar with real thermodynamics that their sectarian religious views have scientific validity.”

Steiger is commenting here on the the ubiquitous use of the dumbed-down version of the second law, namely "everything tends towards maximal disorder", in arguments for or against evolution. There are points of correct argument on both sides of argument and the use of metaphor in this case is way of bringing about communication between lay science users.

Quotes
The following are related quotes:

Metaphors allow us to rephrase the new and puzzling in terms of the homely and familiar, and so provide a staircase for the mind to climb.”
Harold Franklin (1995), “From Morphogenes to Mophogeneis” [5]

References
1. Metaphor (GNU Webster’s 1913 + American Heritage Dictionary) – Wordnik.com.
2. Kundsen, Susanne. (2003). “Scientific Metaphors Going Public” (abs), Journal of Pragmatics, 35(8): 1247-63.
3. (a) Mirowski, Philip. (1991). More Heat Than Light: Economics and Social Physics, Physics as Nature’s Economics (thermodynamic metaphor, pg. 390). Cambridge University Press.
(b) Wells, Kelley J. (1997). “The Thermodynamic Metaphor, Overdetermination, and Peirce’s Commitment to Realism” (abs). Transactions of the Charles S. Peirce Society, 33(4): 899-939.
(c) Stjernfelt, Frederik. (2003). “Thermodynamic Metaphors: A Discussion of Basic Ideas in Cognitive Semantics Exemplified in a Hot Topic” (abs), Semiotica, Issue 146, pgs. 267-85.
4. Steiger, Frank. (1997). “Attributing False Attributes to Thermodynamics”, TalkOrigins.org.
5. Franklin, Harold M. (1995). “From Morphogenes to Mophogeneis”, Microbiology, 141: 2765-2778.
6. (a) Lakoff, George and Johnson, Mark. (1980). Metaphors We Live By. University of Chicago Press.
(b) Lakoff, George. (1987). Women, Fire, and Dangerous Things: What Categories Reveal About the Mind. University of Chicago Press.
(c) Lakoff, George and Turner, Mark. (1989). More Than Cool Reason: A Field Guide to Poetic Metaphor (heat, 12+ pgs). University of Chicago Press.

External links
Metaphor – Wikipedia.
Simile – Wikipedia.
Analogy – Wikipedia.

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