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PC123: Scientific Revolutions

'Tis all in pieces, all cohaerence gone;/ All just supply, and all Relation:/ Prince, Subject, Father, Sonne, are things forgot,/ For every man alone thinkes he hath got/ To be a Phoenix, and that there can bee/ None of that kinde, of which he is, but hee.' — John Donne, “The First Anniversary,” 1611

In 1543 Copernicus took the Earth from its central position in the world and replaced it with the Sun. By 1611 Galileo had turned his telescope to the heavens and found them as changeable and imperfect as the Earth. Because the structure of the universe was intimately woven together with religion and social structure, these changes in the physical world shook the foundations of our relations with each other and with God. John Donne's poetic response illustrates the disorientation of losing your place in the world. Just what was the world in 1611, and how was it changing? We will read from Aristotle, Copernicus, Galileo and Newton to sample the way thinkers have thought about the heavens from the ancient Greeks to the 18th Century.  

Newton's mechanical universe, with its particles moving through a Euclidian three-dimensional space, exerting forces on each other, and marking time with a universal clock, dominated physical thought for more than two centuries. However, early in the 20th century questions about the propagation of light spurred Einstein to revise our ideas of space and time radically. In his theory, moving clocks tick more slowly than stationary clocks, and moving objects measure short, at least in their direction of motion. Even the sequence in which events occur turns out often to be unsettled. If our instinct about the flow of time is wrong, what does this do to our belief in cause and effect? Einstein’s relativity theory retained the strict causality of 18th and 19th Century physics, but it was soon followed by the emergence of quantum mechanics, which revealed the non-deterministic reality at the heart of all things. We will study the physics that drives these questions and then consider some of the impact of physics on the culture of the last century or so.