Before the dawn of science, philosophy reigned supreme. In an effort to understand the natural world, medieval and ancient thinkers pondered ideas and constructed theories. Some of these are still held today and others have been substantially developed. Others have been rejected entirely, their outdated, preposterous ideas deemed obsolete by later scientists.
The Greek thinkers prefigured modern science -- Plato with his ideas of metaphysics, linguistics and mathematics and Aristotle in his studies of physics, metaphysics, biology and zoology. St. Augustine was the first to adapt these concepts for a Christian audience in the fourth century. Drawing on Plato and Plotinus, Augustine used these ideas to advance religion, using a scientific means for a spiritual end. Over the next few hundred years many scholars, mainly from the Arab world, expanded the studies of the natural world, all of which were predicated on the foundations the Greek thinkers had established.
In the fifteenth century, Leonardo da Vinci -- though primarily famous for his artistic endeavors --contributed his creativity to the scientific realm. Da Vinci discovered that falling is an accelerated motion, distinguished between various forms of friction, discovered that sound manifests itself in waves in the air and illuminated many physical phenomena with his eccentric experiments. He was also a lover of invention, creating flying machines, parachutes and other devices hundreds of years before they became commercialized.
Fifty years after da Vinci's death, Galileo Galilei was born. He is famous for his ardent support for the heliocentric concept, that the sun lies at the center of the universe and the world revolves around it, at a time when the Church maintained, as a matter of scriptural truth, that the earth was the center. While condemned by the church in his lifetime, Galileo is considered to be the father of modern science and astronomy. Galileo established the first theories of dynamics, the study of motion of matter, creating a whole new approach to physics and overturning many of Aristotle's methods. Galileo also honed the telescope and was the first to detect Jupiter's moons. Galileo also invented the microscope and built a thermometer, the first device that correctly measured heat.
In the seventeenth century, physics was turned on its head once again with Isaac Newton's work concerning gravity and the three laws of motion. Newton also studied the speed of sound, the refraction of light through a prism and systems of cooling.
Benjamin Franklin was the inventor of bifocals, the lighting rod, the Franklin stove, the glass armonica and the urinary catheter. Franklin also established countless theories of electricity and lightning, oceanography, light waves and cooling that still stand today. A century later, Thomas Edison created over 1,000 inventions in his eighty-four years, most famously the phonograph and the light bulb, putting put Franklin's theories in practice. A two-decade long feud with Nikola Tesla, who was also studying electricity, over whether alternating current (Tesla's invention) was more effective than direct current (Edison's proposal), remained unresolved throughout their lifetimes. After their deaths, it was discovered that Tesla's theory was more practical and is used until today.
Many biological findings cropped up in the early twentieth century. Alexander Fleming stumbled upon penicillin when the substance in his Petri dish became moldy, and Rosalind Franklin discovered how to decipher strands of DNA -- introducing the study of molecular biology.
The twentieth century provided new discoveries about the operation of the universe with the work of a man whose name later became synonymous with genius: Albert Einstein. In 1905, Einstein published a set of papers in which he introduced the most famous equation of all time: E=mc2. This equation helped physicists understand how light works in waves and particles simultaneously, introduced the gravitational and inertia-based effects on time and elucidated the atom's release of radioactivity. The latter part of the theory was the basis of the nuclear bomb. In 1907, Einstein began to develop his theory of relativity, a theory proven to be true twelve years later by a solar eclipse. In 1921, he was awarded the Nobel Prize for Physics and is considered the father of quantum mechanics.
Three centuries to the day from the death of Galileo, Stephen Hawking was born. During his years at Oxford and Cambridge, Hawking discovered that he suffered from Lou Gehrig's disease; he steadily lost his motor abilities. Despite this, Hawking continued to research and teach. He contributed some of the finest knowledge on black holes and substantially expanded Einstein's theory of relativity. Hawking is also a noted figure for having made science accessible to the masses with his book "A Brief History of Time."