Editing Density (section)

== History ==

=== Density, floating, and sinking ===
The understanding that different materials have different densities, and of a relationship between density, floating, and sinking must date to prehistoric times. Much later it was put in writing. [[Aristotle]], for example, wrote:<ref>{{Cite book |last=Aristotle. |url=https://archive.org/details/aristotle0000hdpl/page/n7/mode/2up |title=Meteorologica |publisher=Harvard University Press |year=1952 |pages=2.3, 359a |language=Ancient Greek, English |translator-last=Lee |translator-first=H. D. P. |orig-date=c. 340 BC}}</ref>
{{Blockquote|text=There is so great a difference in density between salt and fresh water that vessels laden with cargoes of the same weight almost sink in rivers, but ride quite easily at sea and are quite seaworthy. And an ignorance of this has sometimes cost people dear who load their ships in rivers. The following is a proof that the density of a fluid is greater when a substance is mixed with it. If you make water very salt by mixing salt in with it, eggs will float on it. ... If there were any truth in the stories they tell about the lake in Palestine it would further bear out what I say. For they say if you bind a man or beast and throw him into it he floats and does not sink beneath the surface.|author=Aristotle|title=[[Meteorologica]]|source=Book II, Chapter III}}

=== Volume vs. density; volume of an irregular shape ===
{{Main|Eureka (word)#Archimedes}}
{{See also|Archimedes#Archimedes and the gold crown}}
In a well-known but probably [[apocrypha]]l tale, [[Archimedes]] was given the task of determining whether [[Hiero II of Syracuse|King Hiero]]'s [[goldsmith]] was embezzling [[gold]] during the manufacture of a golden [[wreath]] dedicated to the gods and replacing it with another, cheaper [[alloy]].<ref>[http://www-personal.umich.edu/~lpt/archimedes.htm Archimedes, A Gold Thief and Buoyancy] {{webarchive|url=https://web.archive.org/web/20070827113533/http://www-personal.umich.edu/~lpt/archimedes.htm |date=August 27, 2007 }} – by Larry "Harris" Taylor, Ph.D.</ref> Archimedes knew that the irregularly shaped wreath could be crushed into a cube whose volume could be calculated easily and compared with the mass; but the king did not approve of this. Baffled, Archimedes is said to have taken an immersion bath and observed from the rise of the water upon entering that he could calculate the volume of the gold wreath through the [[Displacement (fluid)|displacement]] of the water. Upon this discovery, he leapt from his bath and ran naked through the streets shouting, "Eureka! Eureka!" ({{langx|grc|Εύρηκα!||I have found it}}). As a result, the term ''[[Eureka (word)|eureka]]'' entered common parlance and is used today to indicate a moment of enlightenment.

The story first appeared in written form in [[Vitruvius]]' ''[[De architectura|books of architecture]]'', two centuries after it supposedly took place.<ref>[http://webarchive.loc.gov/all/20210420024146/https://penelope.uchicago.edu/Thayer/E/Roman/Texts/Vitruvius/9%2A.html Vitruvius on Architecture, Book IX], paragraphs 9–12, translated into English and [https://penelope.uchicago.edu/Thayer/L/Roman/Texts/Vitruvius/9*.html in the original Latin].</ref> Some scholars have doubted the accuracy of this tale, saying among other things that the method would have required precise measurements that would have been difficult to make at the time.<ref>{{cite journal|doi=10.1126/science.305.5688.1219e|title=EXHIBIT: The First Eureka Moment| year=2004| journal=Science|volume=305|issue=5688|pages=1219e |doi-access=free}}</ref><ref>{{cite news |first=David |last=Biello |title=Fact or Fiction?: Archimedes Coined the Term "Eureka!" in the Bath | work = Scientific American | date = 2006-12-08 |url=https://www.scientificamerican.com/article/fact-or-fiction-archimede }}</ref>

Nevertheless, in 1586, [[Galileo Galilei]], in one of his first experiments, made a possible reconstruction of how the experiment could have been performed with ancient Greek resources<ref>La Bilancetta, Complete text of Galileo's treatise in the original Italian together with a modern English translation [https://math.nyu.edu/~crorres/Archimedes/Crown/bilancetta.html]</ref>