This is the century that split the atom, probed the psyche, spliced genes and cloned a sheep. It invented plastic, radar and the silicon chip. It built airplanes, rockets, satellites, televisions, computers and atom bombs. It overthrew our inherited ideas about logic, language, learning, mathematics, economics and even space and time. And behind each of these great ideas, great discoveries and great inventions is, in most cases, one extraordinary human mind.

• Physicist Albert Einstein He was the pre-eminent scientist in a century dominated by science. The touchstones of the era--the Bomb, the Big Bang, quantum physics and electronics--all bear his imprint.
• Psychoanalyst Sigmund Freud He opened a window on the unconscious--where, he said, lust, rage and repression battle for supremacy--and changed the way we view ourselves
• Chemist Leo Baekeland Setting out to make an insulator, he invented the first true plastic and transformed the world
• Aviators The Wright Brothers A pair of self-taught engineers working in a bicycle shop, they made the world a forever smaller place
• Bacteriologist Alexander Fleming: A spore that drifted into his lab and took root on a culture dish started a chain of events that altered forever the treatment of bacterial infections
• Rocket Scientist Robert Goddard: He launched the space age with a 10-ft. rocket in a New England cabbage field.
• Economist John Maynard Keynes: His radical idea that governments should spend money they don't have may have saved capitalism
• Astronomer Edwin Hubble. He saw a vast universe beyond the Milky Way, then found the first hints that it began with a Big Bang
• Philosopher Ludwig Wittgenstein. He began by trying to reduce all mathematics to logic and ended by finding most metaphysics to be nonsense
• Child Psychologist Jean Piaget . He found the secrets of human learning and knowledge hidden behind the cute and seemingly illogical notions of children
• Atomic Physicist: Enrico Fermi. He was the last of the double-threat physicists: a genius at creating both esoteric theories and elegant experiments
• Anthropologists: The Leakey Family Without the groundbreaking--and backbreaking--efforts of Louis, Mary and Richard, the story of how we evolved would still be largely untold
• Electrical Engineer Philo Farnsworth. The key to the television picture tube came to him at 14, when he was still a farm boy, and he had a working device at 21. Yet he died in obscurity
• Mathematician Kurt Godel.He turned the lens of mathematics on itself and hit upon his famous incompleteness theorem--driving a stake through the heart of formalism
• Environmentalist Rachel Carson. Before there was an environmental movement, there was one brave woman and her very brave book
• Solid-State Physicist William Shockley. He fathered the transistor and brought the silicon to Silicon Valley but is remembered by many only for his noxious racial views
• Computer Scientist: Alan Turing. While addressing a problem in the arcane field of mathematical logic, he imagined a machine that could mimic human reasoning. Sound familiar?
• Virologist Jonas Salk: Many scientists were racing to make a polio vaccine in the '50s--but he got there first
• Molecular Biologists Watson & Crick. It took an ex-physicist and a former ornithology student-- along with some unwitting help from a competitor--to crack the secret of life
• Network Designer Tim Berners-Lee . From the thousands of interconnected threads of the Internet, he wove the World Wide Web and created a mass medium for the 21st century

Information taken from Time.