Murphy’s law
T-Shirt of Murphy's law of thermodynamics: things get worse under pressure (1978). [4]
In folklore, Murphy’s law is the adage “everything that can go wrong will go wrong”, a famous phrase that originated in the 1940s at Edwards Air Force base, California, during the testing of rocket sleds, and named after a Captain Ed Murphy, a development engineer, and his frustration with a repetitive wiring malfunctions. [1]

Thermodynamics
In the style of thermodynamics humor, Murphy’s law came to be referred to as the fourth law of thermodynamics in the 1952 book The Making of a Scientist by Anne Roe. The following are the mentioned excepts:

“There were a number of particularly delightful incidents. There is, for example, the physicist who introduced me to one of my favorite 'laws,' which he described as 'Murphy's law or the fourth law of thermodynamics' (actually there were only three last I heard) which states: 'If anything can go wrong it will.'”

In other places in the book, Roe states: "It was while working on this part of the study that I ran into the perfect exemplification of 'Murphy's law' at one university, where everything that could go wrong did!" or "Certainly this was Murphy's law in operation,--but I will never be the same again."

Sometime after 1952, it seems, Murphy’s law became euphemistically associated with entropy and the second law. [3] One can find T-shirts and posters, for example, stating a Murphy’s law of thermodynamics: “things get worse under pressure.”

References
1. Spark, Nick. (2006). A History of Murphy’s Law (pg. 7). LuLu.com.
2. Roe, Anne. (1952). The Making of a Scientist (Murphy’s law: pgs. 46-47, 214, 224). New York: Dodd, Mead & Co.
3. (a) Handscombe, Robert D. and Patterson, Eann A. (2004). The Entropy Vector: Connecting Business and Science (pg. 134). World Scientific.
(b) Capek, Vladislav. And Sheehan, Daniel P. (2005). Challenges to the Second Law of Thermodynamics: Theory and Experiment (folksy aphorism of the second law: Murphy’s Law (and corollary) (Murphy ~ 1947), pg. 11). Springer.
4. (a) Murphy’s Law of Thermodynamics (Posters, Coasters, T-Shirts) – MurphyWasAnOptimist.com.
(b) Anon. (1978). “Murphy’s Mystery Solved.” (Quote: Murphy’s law of thermodynamics: Things get worse under pressure; Murphy’s philosophy: Smile—tomorrow will be worse.” Human Behavior, Vol. 7.
(c) Peter, Laurence J. (1979). Peter’s People (Quote: Murphy’s law of thermodynamics: Things get worse under pressure, pg. 172). Morrow.

External links
Murphy’s law – Wikipedia.

TDics icon ns