There are a great variety of opinions in response to this question, due mainly to the fact that the 20th Century contained many stupendous events. When I Googled the question, I was presented with many lists. Some of the events that were mentioned on almost every list were the following:
- World Wars I and II (1914-1918 and 1939-1945)
- The Lindburgh transatlantic solo flight (1927)
- The invention of television (1927)
- The first antibiotic — Penicillin (1928)
- The first computer (1936)
- The first heart transplant (1967)
- The first man on the moon (1969)
- The invention of the Internet (1969)
- The first test tube baby (1978)
- The demolition of the Berlin Wall (1991)
I noticed that many, if not most, of the events that were identified as the most significant were dependent upon prior developments that were often more important. Consider, for example:
- The Lindburgh transatlantic flight resulted from the Wright Brother’s invention of the airplane in 1903.
- The first man on the moon was dependent on the development of rocket propulsion in 1926, the invention of the computer in 1936, the launching of the first satellite in 1957 and the first man in space in 1961.
- The destruction of the Berlin Wall was due to a more important event — namely, the collapse of the Soviet Union in 1991.
- The many marvelous developments in the health sciences were dependent on biological discoveries that dated back to the 19th Century, like the development of the germ theory of disease in the 1860s.
The Most Important Event From the World’s Viewpoint
The event that was named on the Google lists more than any other as the most important event of the 20th Century was the dropping of the atomic bomb on Hiroshima, Japan in August of 1945. But this event was also dependent upon many theories, experiments and tests that preceded it. Here is a list of some of them:1
- 400 BC — The Greek philosopher, Democritus (460-370 BC) postulated that the fundamental building block of all matter was what he called the “atom.”
- 1803 — A British chemist, John Dalton (1766-1844), developed a more scientific definition of the atom, describing it as a small, hard sphere that is indivisible.
- 1904 — J. J. Thomson (1856-1940), an English physicist, discovered the electron.
- 1905 — Albert Einstein (1879-1955) proposed the formula, E=mc2, which indicated the power potential of converting a tiny amount of mass into enormous energy, something that could happen with the splitting of the atom if a sustained reaction could be attained.2
- 1911 — Ernest Rutherford (1871-1937) of New Zealand theorized that the atom had a nucleus and that electrons orbit the nucleus. The result was what came to be known as the planetary model of the atom — a nucleus surrounded by orbiting electrons.3
- 1917 — Rutherford split the atom at Manchester University in England and discovered the proton.
- 1921 — Rutherford theorized the existence of neutrons in the nucleus of the atom.
- 1932 — Rutherford’s student, James Chadwick, a British physicist, proved the nucleus of the atom contained neutrons clustered with protons.
- 1936 — Erwin Schrodinger (1887-1961), an Austrian scientist, proved that electrons do not orbit the nucleus in set paths, but in waves.4
- 1938 — Discovery of nuclear fission by Schrodinger and a German chemist, Otto Hahn (1879-1968).
A Seminal Event
This intriguing historical process of discovery culminated on December 2, 1942, at 3:25pm, when the first artificial nuclear reactor produced the first human-made, self-sustaining nuclear chain reaction. The scientist in charge was an Italian-American, Enrico Fermi (1901- 1954).5
This momentous event took place on a squash court located under the bleachers of Stagg Field — the University of Chicago’s abandoned football stadium. It was an incredible accomplishment which marked the advent of the Nuclear Age.
One of the persons present, University of Chicago physicist, Samuel K. Allison (1900-1965), wrote at the time: “All of us knew that with the advent of the chain reaction, the world would never be the same again.”6 Secretary of War, Henry L. Stimson (1867-1950), called the chain reaction “the greatest achievement of organized science in history.”7
In the second part of this look at what the greatest event of the 20th Century was, we’ll explore the possibility that the event was the advent of the atomic bomb.
1) “The History of the Atom: Theories and Models” (www.compoundchem.com/2016/10/13/atomicmodels); “The History of the Atom” (www.sisd.net/cms/lib/TX01001452/Centricity/Domain/1297/The_history_of_the_atom_ Notes _condensed.pdf); and “History of Atomic Structure” (https://courses.lumenlearning.com/boundlesschemistry/chapter/history of atomic structure).
2) “Einstein’s Equation” (www.atomicarchive.com/Physics/Physics4.shtml) and Robert Lamb, “What does Einstein’s famous equation really mean?” (https://science.howstuffworks.com/science vs myth/everyday myths/einstein formula.htm).
3) Wikipedia, “Ernest Rutherford” (https://en.wikipedia.org/wiki/Ernest_Rutherford).
4) “The History of the Atom: Theories and Models” (www.compoundchem.com/2016/10/13/atomicmodels), page 5.
5) Steve Koppes, “How the first chain reaction changed science” (https://www.uchicago.edu/features/how_the_first_ chain_reaction_changed_science), and Wikipedia, “Chicago Pile-1” (https://en.wikipedia.org/wiki/Chicago_Pile 1).
6) Steve Koppes, page 1.
7) “Henry Stimson’s Letter to President Truman (1945)” (https://teachinghistory.org/history content/beyond the textbook/25484?subpage=2), page 2.