Kannan Jagannathan (Section 01)
As a boy of ten Einstein famously imagined chasing a light beam on its way to a mirror and wondered if he would see his reflection in such an event. Later in life, he was struck by the conflict such a hypothetical experiment would create with other parts of experience and physical theory. This reflection (or its absence!) eventually led him to the formulation of the special theory of relativity. The kind of reasoning Einstein undertook as a boy goes by the name gedankenexperiment or thought-experiment. In fact before Einstein, different kinds of thought-experiments had been used by Galileo, Newton and Maxwell among others in their path-breaking contributions to physics. The common element in these works in the philosopher Martin Cohen's words "is the discovery of a way of seeing the world" rather than making an observation or measurement. In this seminar we will take up the thought experiments considered by these and other physicists as a primary means of gaining some insights into aspects of space, time, motion, thermodynamics, relativity, gravity and quantum physics. We will also examine the different kinds of thought experiments and inquire into the peculiar status they have in producing knowledge or understanding.
This course does not require a background in science, but we will be reading sources that make use of some geometry and mathematical reasoning. In addition, students will be assigned simple problem sets involving numerical and graphical work based on high school mathematics. The aim of these exercises is to teach parts of fundamental physics that are accessible without a strong technical background, but with some attention to epistemological considerations; while some historical context will be essential, our main focus will not be on issues in history of science. The course will require a fair amount of writing, including short papers on the strengths and limitations of the particular arguments advanced by our sources and a final paper on the philosophical questions raised by thought-experiments.
Fall semester. Professor Jagannathan.