
A visual of something "hot" (Ѻ), i.e. fire, shown next to something "cold", i.e. ice, the latter working to melt the former.

A visual of something "hot" (Ѻ), i.e. fire, shown next to something "cold", i.e. ice, the latter working to melt the former.

In science, hot, as contrasted with “cold” (i.e. cold body), refers to a description a body (i.e. hot body), or system, whose internal parts have a higher state of “motion” (Bacon, 1620), gauged, via zeroth law, by a third body, the thermometer, which discerns the relative state of motion, or temperature; which decreases to a minimum at absolute zero, according to the third law. [1]

Societies
In circa 1959, Claude Levi-Strauss outlined ideas on how he conceived societies as either being hot, i.e. “hot societies” (hot social system), or cold, i.e. “cold societies” (cold social system).

Hot or Not
In 2000, American electrical engineers James Hong and Jim Young launched the visually attractiveness rating site HotOrNot.com, aka “Hot or Not”, the 2015 logo of which is as follows:

according to which photos of people are "rated" on a supposedly (depending up opinion) "metaphorical" hot-to-cold scale of 10 (hot) to 1 (cold), thereby giving a common consensus gauge of the relative "hotness" or "coldness" of the visual nature of a person; the site was conceived as a technical solution to a disagreement they made one day over a passing woman’s attractiveness. [2]

In circa 2003, Libb Thims, amid the drafting of his Human Thermodynamics manuscript, was using the site to conduct scientific studies.

In 2005, imaging researcher Pierre Tourigny, supposedly aware of the beauty rule of the thumb that “averageness” equates to attractiveness, selected 30 random photos from Hot or Not, spanning the attractiveness range, and morphed the photos, three per each 0.5 hotness range, as well as the thirty photos as a group; the following being the results: (Ѻ)

The following shows the composite "average" photo, a morph of all 30 photos, as compared to the morph of the three vote-deemed hottest morph:

(add discussion)

Quotes
The following are related quotes:

“Put your hand on a hot stove for a minute and it seems like an hour. Sit with a pretty girl for an hour, and it seems like a minute. That's relativity!”
— Albert Einstein (1921) (Ѻ)

“A woman is like a tea bag—you can't tell how strong she is until you put her in hot water.”
— Eleanor Roosevelt (c.1930) (Ѻ)

“I think human thermodynamics is pseudoscience. The interchanging of words with precise scientific meanings, i.e. bond, energy, reaction, hot, etc., with their everyday meanings is one of the cornerstones of pseudoscience. Of course human beings obey the laws of thermodynamics like everything else in the universe, but trying to apply equations which only describe larger systems of microscopic particles to analogous situations between human beings, just because the everyday and scientific words involved happen to correspond, [is erroneous].”
— Edward Sanville (2005), “Dialogue with Libb Thims on Human Thermodynamics” [4]

References
1. (a) Bacon, Francis. (1620). New Instrument of Science (Novum Organum Scientiarum (§:First Vintage Concerning the Form of Heat), in: The Works of Francis Bacon (pg. 149-). Publisher.
(b) Novum Organum – Wikipedia.
2. (a) Home – HotOrNot.com.
(b) Hot or Not – Wikipedia.
3. Sanville, Edward and Thims, Libb. (2005). "Human Thermodynamics: Science or Pseudoscience", conversation originating on Wikipedia talk pages (Sep–Oct). IoHT Publications.

Further reading
● Thims, Libb. (c.2006). “Hot or Not by Age” (Ѻ), Chicago: IoHT publications.

Videos
● Thims, Libb. (2008). “Thermodynamics of Hot for Words”, YouTube, HumanChemist101, Nov 26.
● Thims, Libb. (2009). “Hot N Cold: Relationships”, HumanChemistry101, YouTube.com, Mar 04.