Richard Feynman on the differences of merely knowing how to reason mathematically and understanding how and why things are physically analyzed in the way they are.

Physicist Richard Feynman explains the scientific and unscientific methods of understanding nature.

The early 1900s was an amazing time for Western science. Einstein's theories of relativity and Freud's psychoanalysis took over the scientific mainstream. Karl Popper observed these developments and came to draw a distinction between science and what he called 'pseudoscience'.

A reading from "Conjectures and Refutations" (1963).

For tens of thousands of years our ancestors understood the world through myths, and the pace of change was glacial. The rise of scientific understanding transformed the world within a few centuries. Why? Physicist David Deutsch proposes a subtle answer.

What is information? Information is all the rage in science, changing how we think about fundamental questions. Information has many descriptions, some of them surprising. Why is Information so important to scientists and philosophers? Featuring interviews with Max Tegmark, Paul Davies, Seth Lloyd, Giulio Tononi, and Scott Aaronson.

To appreciate Time is to touch the texture of reality. Does Time differ from our common perceptions of it? Is Time fixed or flexible? What is time, really? Featuring interviews with Huw Price, Julian Barbour, David Albert, Jeff Tollaksen, and John Polkinghorne.

Time seems natural and absolute: the flow of moments one following another from the unknown past to the knife's edge present to the unknowable future. But this is not so. Einstein shocked the world by showing that time was "relative." What's the latest about time? Featuring interviews with Gregory Benford, Kip Thorne, Nima Arkani-Hamed, and Lee Smolin.

What makes a human being a "person?" What provides our sense of unity and continuity? While most people assume that to be a person is to have a soul, most philosophers-and some theologians-believe that persons are all material. Featuring interviews with Daniel Dennett, Alvin Plantinga, Peter van Inwagen, John Searle, and David Chalmers.