In nature, death is the termination of life. [1]

Cultural death
In 1944, American anthropologist Alfred Kroeber defined the death of a society or cultural “dying”, in what seem to be physical chemistry terms, as follows: [6]

“Cultural dying is a replacement of most of the material and patterns with new material and patterns developed within the culture, until after a sufficient length of time, the transformation is so great that it is descriptively more useful to speak of the end product as a new culture, or one different from the original one.”

This is an intuitive view being that what are perceptually conceived as "biological entities", such as birds and bees, are actually carbon-centric reactive molecules, formed through chemical reaction synthesis, and transformed likewise in a reverse type of reaction, but do not actually "live" or "die", in a physical chemistry sense.

Heat death
In the 1850s, Scottish physicist William Thomson and German physicist Rudolf Clausius proposed the "heat death" end state model of the universe. [3]

In 1944, Austrian physicist physicist Erwin Schrödinger defined death, thermodynamically, as "the dangerous state of maximum entropy". [2] The study of what happens to a person when they die, according to the laws of thermodynamics, is called cessation thermodynamics. [4]

Author Stephen Haines, an engineer, management consultant, and human systems theorist, states, based on extrapolations of the heat death theory, that entropy refers to the natural characteristic of all living systems to eventually slow down and die. [5]

References
1. Death (definition) - Merriam-Webster's Collegiate Dictionary (2000), CD-Rom, version 2.5.
2. Schrödinger, Erwin. (1944). What is Life? (ch. 6 “Order, Disorder, and Entropy). pgs. 67-75 Cambridge: Cambridge University Press.
3. Thomson, William. (1862). “On the age of the sun’s heat”, Macmillan’s Mag., 5, 288-93; PL, 1, 394-68.
4. Thims, Libb. (2007). Human Chemistry (Volume Two) (preview), Ch 16: section "Cessation Thermodynamics", (693-699). Morrisville, NC: LuLu.
5. Haines, Stephen G. (2000). The Complete Guide to Systems Thinking and Learning (pg. 19). HRD Press.
6. (a) Kroeber, Alfred L. (1944). Configurations of Culture Growth (pg. 820). University of California Press.
(b) Wallace, Thomas P. (2009). Wealth, Energy, and Human Values: the Dynamics of Decaying Civilizations from Ancient Greece to America (pg. 231). AuthorHouse.

External links
● Death – Wikipedia.