Thirteen discoveries that help explain why matter and energy behave as they do: Galileo's law of falling bodies, Isaac Newton's conclusions of universal gravity, Newton's laws of motion, the second law of thermodynamics, experiments in electromagnetism, Albert Einstein's Special Theory of Relativity and his equation E=mc2, Quantum theory, calculations on the nature of light, James Chadwick's discovery of the neutron, the development of superconductivity, Murray Gell-Mann's proposal of quarks, and the discovery of the strong and weak nuclear forces.

Twelve landmark steps to understanding the Earth's structure: Richard Oldham's theory of a liquid core, Inge Lehmann's conclusion that the core is solid iron, Alfred Wegener's premise of continental drift, Harry Hess's findings on seafloor spreading, plate tectonics, Leon Teisserenc de Bort's discovery of atmospheric layers, the theory of global warming, Victor Hess's studies of cosmic rays, Bernard Brunhes's assertion of magnetic field reversal, Charles Lyell's ideas on geological change, Bertram Boltwood's formulas for radiometric dating, and Milutin Milankovitch's ideas on periodic ice ages.

Thirteen crucial benchmarks in the history of what may be the oldest science: Ancient awareness that the planets move, Copernican cosmology, Johannes Kepler's laws of planetary motion, Galileo's discovery of Jupiter's moons, Edmund Halley's comet prediction, William and Carolyn Herschel's galactic mapping, Einstein's General Theory of Relativity, Edwin Hubble's proof that the universe is expanding, Karl Jansky's discovery of galactic radio waves, Arno Penzias and Robert Wilson's detection of the cosmic microwave background, observations of gamma ray bursts, the discovery of extrasolar planets, and the "big rip" theory.

Ten milestones that have helped to tell life's story: Walter Alvarez's asteroid theory of dinosaur extinction, the first identification of dinosaur fossils Stanley Miller's simulation of the early atmosphere, Robert Ballard's discovery of hydrothermal vent ecosystems, Charles Walcott's analysis of the Burgess Shale, the Linnaean classification system, Darwin's theory of natural selection, Donald Johanson's Lucy, Mary Leakey's Laetoli footprints, and Michel Brunet's Toumai skull.

Thirteen achievements in medicine: Andreas Vesalius's anatomical charts, William Harvey's breakthrough on blood circulation, Karl Landsteiner's identification of blood groups, the development of anesthesia, Wilhelm Roentgen's discovery of X-rays, Louis Pasteur's establishment of bacteriology, Frederick Hopkins's recognition of the importance of vitamins, the discovery and isolation of penicillin, the development of sulfa drugs, Edward Jenner's invention of vaccine, and the discoveries of insulin, oncogenes and the human immunodeficiency virus (HIV).

Thirteen building blocks in a science that may be the foundation of the modern world: Joseph Priestly and Antoine Lavoisier's discovery of oxygen, John Dalton's atomic theory, Avogadro's Law, Friedrich Woehler's synthesis of urea, Friedrich Kekule's studies of molecular structure, Dmitry Mendeleyev's Periodic Table, Humphry Davy's electrolysis, J. J. Thomson's discovery of the electron, Niels Bohr's model of atomic structure, Gustav Kirchhoff and Robert Bunson's electromagnetic spectroscopy, Marie Curie's isolation of radioactive materials, John Wesley Hyatt and Leo Baekeland's invention of plastics, and the discovery of fullerenes.

Thirteen breakthroughs in the science of living things: Anton van Leeuwenhoek's discovery of micro-organisms, Robert Brown's identification of cell nuclei, Carl Woese's Archaea classification, Walther Flemming and Eduard Strasburger's discovery of mitosis, August Weismann's conclusions on meiosis, Awareness of cell differentiation and stem cells, Pinpointing of mitochondria, Hans Krebs' citric acid cycle, The discoveries of neurotransmitters, hormones and photosynthesis, Arthur George Tansley's ideas on ecosystems, and the centuries-long process of studying biodiversity.

Thirteen vital contributions to a field tht is now a cornerstone of the life sciences: Gregor Mendel's rules of heredity, Thomas Hunt Morgan's detection of chromosomal gene location, George Beadle and Edward Tatum's "one gene, one enzyme" concept, Barbara McClintock's discovery of transposons, the acceptance of DNA as the basis of genetic information, James Watson and Francis Crick's double helix, Marshall Nirenberg's genetic code, the discoveries of RNA, restriction enzymes, RNA splicing and RNA interference, Alec Jeffreys' DNA identification technique, and the Human Genome Project.