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1948 The U.S. Air Force starts Project Blue Book to gather data on UFO sightings
1948 Alfred Kinsey publishes Sexual Behavior in the Human Male
1950
1952 British physician Douglas Bevis describes amniocentesis, a prenatal test for genetic abnormalities
1952 U.S. virologist Jonas Salk develops the first effective polio vaccine
1952 British chemist Rosalind Franklin's X-ray photographs of DNA show that the molecule has a helical structure
1952 The first sex-change operation is performed on a patient named George Jorgenson, later known as Christine Jorgenson
1953 James Watson and Francis Crick announce that they have deciphered the structure of DNA
1954 U.S. endocrinologists Gregory Pincus, John Rock and C.R. Garcia develop the birth-control pill
1956 The U.S. explodes a hydrogen bomb at Bikini Atoll, in the South Pacific
1957 A new sleeping pill, thalidomide, is prescribed in Britain and Germany. It is later found to cause severe birth defects and taken off the market
1957 Soviets send the first artificial satellite, Sputnik, into orbit around Earth
1958 John Kenneth Galbraith publishes The Affluent Society
1958 Electrical engineer Wilson Greatbatch invents the first implantable cardiac pacemaker; it is powered by a zinc-mercury battery
1959 In Tanzania's Olduvai Gorge, Mary Leakey finds the fossilized skull of a human ancestor who lived 1.8 million years ago
1959 Engineer Robert Noyce makes the first integrated circuit, or microchip
1959 Marvin Minsky and John McCarthy establish the Artificial Intelligence Laboratory at M.I.T.
1960
1960 The bathyscaphe Trieste descends 35,800 ft. in the Mariana Trench to the deepest spot in the oceans
1960 U.S. physicist Theodore Maiman builds a working laser
1960 British ethologist Jane Goodall begins studying chimpanzee behavior in Tanzania
1960 The discovery of an 11th century Norse settlement at L'Anse aux Meadows, Newfoundland, confirms that Europeans reached the New World centuries earlier than Columbus did
1961 American astronomers Allan Sandage and Thomas Matthews discover quasars
1962 U.S. marine biologist Rachel Carson publishes Silent Spring
1963 The tranquilizer Valium is introduced
1964 The U.S. Surgeon General first warns that smoking can be hazardous to human health
1964 U.S. surgeon Michael DeBakey performs the first successful coronary-artery bypass operation
1965 American radio astronomers Arno Penzias and Robert Wilson accidentally discover cosmic background radiation, which bolsters the Big Bang theory of the origin of the universe
1967 R. Buckminster Fuller's geodesic dome is a hit at the Montreal Exposition
1967 South African surgeon Christiaan Barnard performs the first successful human-heart transplant; his patient, Louis Washkansky, survives 18 days
1969 American astronauts walk on the moon
1969 Swiss-born psychiatrist Elisabeth Kubler-Ross publishes On Death and Dying
1970
1970 American biochemist Linus Pauling touts vitamin C as a cure for everything from cancer to the common cold