Copernicus proposed the heliocentric model! His theory was not immediately accepted; it took over a century to become mainstream. Copernicus was a canon (church official) in Poland. He studied mathematics, astronomy, medicine, and law. His book was dedicated to Pope Paul III, and it was not banned by the Catholic Church until 1616 (after Galileo's trial). The Copernican Revolution fundamentally changed humanity's understanding of our place in the universe. Copernicus died on May 24, 1543, the day his book was published. Legend says he held a copy of the book on his deathbed. His remains were reburied in Frombork Cathedral in 2010 after being identified by DNA analysis.

The scientific method was developed during the Scientific Revolution! Francis Bacon (1561–1626) advocated for empirical methods and inductive reasoning. René Descartes (1596–1650) emphasized deductive reasoning and mathematics. The scientific method emphasized that knowledge should be based on evidence, not tradition or authority. Galileo used the telescope to observe the moons of Jupiter, the phases of Venus, and sunspots, providing evidence for the heliocentric model. William Harvey discovered the circulation of blood (1628). Antonie van Leeuwenhoek discovered microorganisms (1670s). The Royal Society of London (founded 1660) and the French Academy of Sciences (1666) promoted scientific research. The Scientific Revolution laid the foundation for the Industrial Revolution and modern science.

Pasteurization was invented by Louis Pasteur! He originally developed it to prevent wine and beer from spoiling. The process involves heating the liquid to 60-70°C (140-160°F) for a short time, then cooling it rapidly. Pasteur also disproved spontaneous generation (the idea that life arises from non-living matter) through his famous swan-neck flask experiment. His rabies vaccine saved a young boy named Joseph Meister (1885), who had been bitten by a rabid dog. The Pasteur Institute opened in 1888. Pasteur suffered a stroke in 1868 that partially paralyzed him, but he continued working. He is buried at the Pasteur Institute in Paris. The process named after him (pasteurization) is used worldwide to make milk safe.

Natural selection is often called "survival of the fittest" (a term coined by Herbert Spencer, not Darwin). Darwin observed finches on the Galápagos Islands with different beak shapes adapted to different food sources. He spent over 20 years gathering evidence before publishing his theory, partly because he feared controversy. When he finally published, he was shocked by the reaction. Thomas Huxley ("Darwin's Bulldog") defended him vigorously. The famous Oxford debate (1860) between Huxley and Bishop Wilberforce turned the tide of public opinion. Darwin's theory was not fully accepted until the early 20th century, when genetics (Gregor Mendel) provided the mechanism. Darwin is buried in Westminster Abbey (near Isaac Newton).

Mendel used pea plants! He grew over 28,000 pea plants over seven years. He studied seven traits: seed shape (round/wrinkled), seed color (yellow/green), flower color (purple/white), pod shape (inflated/constricted), pod color (green/yellow), flower position (axial/terminal), and stem height (tall/short). He discovered that traits are inherited as discrete units (now called genes). His work was ignored because he published in an obscure journal and was not a famous scientist. Around 1900, Carl Correns, Hugo de Vries, and Erich von Tschermak independently rediscovered Mendel's laws. The "Mendelian ratio" (3:1) is fundamental to genetics. Mendel became an abbot later in life and stopped his experiments due to administrative duties. His work was controversial because evolution (Darwin) suggested blending inheritance, but Mendel showed it was particulate.

Penicillin was the first antibiotic! Fleming's discovery was accidental – he had left a Petri dish uncovered and mold spores landed on it. He famously said: "One sometimes finds what one is not looking for." He published his findings in 1929 but could not purify penicillin in large quantities. Florey and Chain continued the work, successfully treating the first patient in 1941. By 1944, penicillin was being mass-produced for Allied soldiers. Fleming, Florey, and Chain shared the Nobel Prize. Fleming warned about antibiotic resistance: "The microbes are educated to resist penicillin." His warning was prescient – antibiotic resistance is now a major global health crisis. Fleming was a modest man; he was knighted in 1944. He died of a heart attack in 1955. The discovery of penicillin has been called the greatest medical breakthrough of the 20th century.

DNA is a double helix! The discovery of DNA's structure was a landmark in biology. Watson and Crick published a one-page paper in Nature in April 1953. Francis Crick is often quoted saying, "We have discovered the secret of life." The double helix model explained how genetic information is stored and replicated. The Human Genome Project (completed in 2003) sequenced all 3 billion base pairs of human DNA. Rosalind Franklin's contribution was largely overlooked during her lifetime; her Photo 51 was shown to Watson without her knowledge. She is now recognized as a key contributor. Watson and Crick both lived long lives; Crick died in 2004, Watson is still alive (born 1928). Watson has been controversial for his later statements on race and intelligence.

Pangaea was the supercontinent! Wegener published his theory in "The Origin of Continents and Oceans" (1915). He was a meteorologist, not a geologist, which made geologists skeptical. He died in 1930 during an expedition in Greenland; his theory was still widely rejected. In the 1960s, Harry Hess (seafloor spreading) and others provided the mechanism Wegener lacked. The theory of plate tectonics explains earthquakes, volcanoes, and mountain formation (Himalayas, Andes). The continents continue to drift today – about 1-2 inches per year. The next supercontinent (Pangaea Ultima) is predicted to form in about 250 million years. Wegener's work is now celebrated as a major scientific breakthrough. He would not live to see his theory vindicated.

Edwin Hubble observed that galaxies are moving away! He measured the redshift of galaxies and found that the farther a galaxy is, the faster it is moving away (Hubble's Law). This was the first observational evidence for an expanding universe. Hubble had a namesake telescope (Hubble Space Telescope) launched in 1990, which has made countless discoveries. The Big Bang theory was initially mocked (Fred Hoyle coined the term "Big Bang" as a pejorative). The discovery of cosmic microwave background radiation (1965) by Penzias and Wilson confirmed the Big Bang. The universe is still expanding today. The theory does not explain what caused the Big Bang or what existed before. The James Webb Space Telescope (launched 2021) is studying the early universe.

Smallpox was eradicated! Edward Jenner's vaccine was the first. The last naturally occurring case of smallpox was in Somalia in 1977. The World Health Organization (WHO) certified eradication in 1980. Smallpox killed an estimated 300-500 million people in the 20th century alone (more than all wars combined). Smallpox vaccines are no longer routinely given because the disease no longer exists (samples remain in two labs: CDC in Atlanta and VECTOR in Russia). Jenner faced criticism and ridicule, but his vaccine saved countless lives. The word "vaccine" comes from "vacca" (cow). Jenner was a country doctor in Gloucestershire, England. He is buried in Berkeley, Gloucestershire. A statue of him stands in Trafalgar Square (London) and in Kensington Gardens. The Jenner Institute at Oxford University (developers of a COVID-19 vaccine) is named in his honor.