Lived c. 610 BC – c. 546 BC.
is responsible for the idea that the earth needs nothing below it to support it. He said that the earth floats in the center of infinity, held in position because it is an equal distance from all the other parts of the universe. In doing so, he transformed the way we think of our planet and simultaneously introduced the idea of a force of attraction between the earth and the planets and stars in the heavens.
“In my opinion this idea of Anaximander’s is one of the boldest, most revolutionary, and most portentous ideas in the whole history of human thought.”
KARL POPPER, 1902 – 1994
Philosopher of Science
Lived c. 287 BC – 212 BC.
The greatest scientist of ancient times, Archimedes
pushed mathematics, physics, and engineering to new heights. He created the physical sciences of mechanics and hydrostatics, discovered the laws of levers and pulleys, and discovered one of the most important concepts in physics – the center of gravity. He applied advanced mathematics to the physical world and his surviving works inspired both Galileo Galilei and Isaac Newton to investigate the laws of motion.
Lived 1564 – 1642.
was one of the first people to study the sky with a telescope. He was the first person to discover moons orbiting another planet, discovering Jupiter’s four largest moons. He discovered that Venus has phases like our moon – the first practical rather than mathematical evidence that the sun is at the center of the solar system. He discovered the Law of the Pendulum. He discovered that gravity accelerates all things equally, regardless of mass, and that acceleration of objects by gravity is proportional to the square of the time they have been falling. He stated the principle of inertia – in other words he discovered Newton’s First Law of Motion. His discoveries in the field of mechanics shattered the mistaken physics of Aristotle that had dominated Western thought for two millennia.
Lived 1571 to 1630.
Johannes Kepler broke the tradition of thousands of years of astronomy, discovering that the heavenly bodies follow elliptical paths. Kepler’s laws of planetary motion were an absolutely crucial breakthrough in our understanding of the universe. Kepler’s third law enabled Isaac Newton to establish the inverse square law of gravitation. Kepler himself discovered the inverse square law of light intensity. He discovered that our eyes invert images and our brains correct the upside down images. He was the first person to prove how logarithms work, allowing physical scientists to use these fundamental tools free of anxiety.
Lived 1643 to 1727.
invented calculus, the mathematics of change, without which we could not understand the behavior of objects as tiny as electrons or as large as galaxies. His most famous work, Principia
, is one of the most important scientific books ever written. In Principia
Newton used mathematics to explain gravity and motion. Initially hardly anyone understood Newton’s new physics. When Newton walked past them one day, one student remarked to another:
“There goes a man who has written a book that neither he nor anybody else understands.”
Newton discovered the law of universal gravitation, proving that the moon orbits the earth for precisely the same reason that an apple falls from a tree. He formulated three laws of motion – Newton’s Laws – which lie at the heart of the science of movement. Furthermore, he proved that sunlight is made up of all of the colors of the rainbow and he built the world’s first working reflecting telescope.
Lived 1791 to 1867.
is probably the greatest experimental physicist ever. By varying a magnetic field he produced electric current in a wire, and so discovered electromagnetic induction, the means by which nearly all electricity is generated by power plants today. He discovered electromagnetic rotation – the forerunner of the electric motor – and he discovered that diamagnetism is a property of all materials. His laws of electrolysis lie at the heart of electrochemistry, which he played a large part in founding. He invented the Faraday Cage, which prevents lightning damaging anything within it and prevents external interference affecting sensitive electric and electronic experiments. He discovered that magnetism and light are related by showing that a magnetic field rotates the plane of light polarization. He was the first person to liquefy gases, and he discovered the enormously important chemical compound benzene.
James Clerk Maxwell
Lived 1831 – 1879.
James Clerk Maxwell’s
work heralded a new epoch in physics – he unified the electric and magnetic forces, showing that they are fundamentally the same force. His equations showed that when electric charges accelerate they release waves of electromagnetism traveling at the speed of light, establishing that light itself is an electromagnetic phenomenon – in doing so he unified electricity, magnetism and optics. His kinetic theory of gases accurately explained the origin of temperature and he introduced probability theory into the physics of the very small, which today is indispensible. He was the first person ever to produce a color photograph; and, with tremendous mathematical and physical intuition, he explained the behavior of Saturn’s rings over 100 years before the Voyager spacecraft confirmed that he was absolutely right.
Lived 1871 – 1937.
is the father of nuclear chemistry and nuclear physics. He discovered and named the atomic nucleus, the proton, the alpha particle, the beta particle, and he predicted the existence of the neutron. He discovered the concept of nuclear half-lives and achieved the first deliberate transformation of one element into another, fulfilling one of the ancient passions of the alchemists. An unusually large number of young scientists who spent time working with him went on to win Nobel Prizes, including James Chadwick, Cecil Powell, Niels Bohr, Otto Hahn, Frederick Soddy, John Cockcroft, Ernest Walton and Edward Appleton.
Lived 1879 – 1955.
rewrote the laws of nature. He completely changed the way we understand the behavior of things as basic as light, gravity, space and time. He established that everyone, whatever their own speed relative to light, measures the speed of light to be 300 million meters per second in a vacuum. This led to the strange new reality that time passes more slowly for people traveling at very high speeds than for people moving more slowly. Hence space and time actually merge into the single phenomenon of space-time.
He discovered the iconic equation, E = mc2, which shows that energy and matter can be converted into one another. He rewrote Newton’s law of gravitation, which had been unchallenged since 1687. In his General Theory of Relativity, Einstein showed that matter causes space-time to curve, which produces the phenomenon that we call gravity; he showed that the path of light follows the gravitational curve of space; and he showed that time passes more slowly when gravity becomes very strong. He also demonstrated the photoelectric effect, establishing that light can behave as both a wave and a particle.
Lived 1885 – 1962.
completely transformed our view of the atom and of the world. Realizing that classical physics fails catastrophically when things are atom-sized or smaller, he remodeled the atom so electrons occupied ‘allowed’ orbits around the nucleus while all other orbits were forbidden. In doing so he founded quantum mechanics. Later, as a leading architect of the Copenhagen interpretation of quantum mechanics, he helped to reshape our understanding of how nature operates at the atomic-scale.
Lived 1901 – 1976.
played a crucial role in the creation of quantum mechanics, developing the matrix mechanics formulation, establishing that the behavior of atomic sized particles is very different from larger objects, sometimes with bizarre consequences. Although Albert Einstein did not like it, Heisenberg showed that God continuously plays dice with the universe. Heisenberg’s uncertainty principle established that particles have paired properties that cannot both be known precisely. For example, if you know a particle’s position with high precision, you cannot know its momentum with high precision – there is always a level of uncertainty.
Lived 1887 – 1961.
Erwin Schrödinger established the wave mechanics formulation of quantum mechanics which, in contrast to Werner Heisenberg’s matrix formulation, allowed a degree of visualization. Schrödinger portrayed electrons as waves, spread out rather than in any given location. He showed that his wave and Heisenberg’s matrix formulations, although superficially different, were mathematically equivalent. In his later years, Schrödinger became unhappy with quantum mechanics and is famous for the Schrödinger’s cat thought experiment, in which he attempted to show the absurdity of the Copenhagen interpretation of quantum mechanics.
Surprisingly, for a physicist, his favorite book of all time was Charles Darwin’s The Origin of Species. Schrödinger’s 1944 book What is Life?, although not entirely original, had a profound effect on the future of genetics and molecular biology. Schrödinger wrote that the gene was an aperiodic crystal – a code script for life. His book inspired a number of scientists – including three of the main players in the discovery of DNA’s structure – Francis Crick, James Watson and Maurice Wilkins – to pursue research in that field.
Lived 1902 – 1984.
Paul Dirac completely reshaped quantum mechanics with the astounding Dirac Equation. The Dirac Equation explained the behavior of electrons, including those traveling at relativistic speeds, and foretold the existence of antimatter. Dirac was also able to infer the existence of vacuum polarization, revealing that what we once believed was empty space is actually awash with short-lived particle-antiparticle pairs.
Dirac founded quantum electrodynamics, accounting for the creation and annihilation of photons of light within atoms, and his Lagrangian formulation of quantum mechanics led to Richard Feynman’s path integrals. Dirac showed that quantization of electric charge occurs naturally if a magnetic monopole exists somewhere in the universe. He also created a prototype string theory.
Lived 1918 – 1988.
Richard Feynman developed Dirac’s Lagrangian formulation of quantum mechanics into a complete, useable method using path integrals. From there he developed the new mathematical language of Feynman diagrams, which made accurate calculations in quantum electrodynamics both possible and convenient. Feynman diagrams are now indispensable for calculations in quantum field theories, including the Standard Model of particle physics. In 1957, Feynman explained parity violation in weak nuclear force interactions – the theory is known as the Feynman-Gell-Mann Sudarshan-Marshak theory.
Nanotechnology was Feynman’s creation. In 1959 he delivered his There’s Plenty of Room at the Bottom lecture at Caltech. Feynman’s visionary talk considered, among other things, what could be achieved if scientists could manipulate individual atoms. Although Feynman’s vision made little impact at the time, technology has more recently been catching up with his ideas.
Feynman’s charismatic and engaging way of talking about physics left a deep impression, inspiring both scientists and non-scientists to learn more about the way our world works.