The Teaching Company publishes a series of taped lectures by leading scholars. They are expensive but enjoyable, and they cover almost all areas of scholarly study. I tend to get the lectures dealing with history, theology, and philosophy, but occasionally I like to listen to some of the lectures on science. I just finished Steven L. Goldman's "Great Scientific Ideas that Changed the World." it is excellent.
Goldman starts slowly, beginning with the invention of writing, and works in rough
chronological order through the notable scientific ideas which have shaped the
modern West. When he comes to the end of his series of lectures you will have
been introduced to a dizzying array of scientific theories, discoveries, and
ideas. Copernican cosmology, Newtonian physics, quantum mechanics, chaos
theory, molecular biology, relativity, evolution, and many more. You will learn
how the laws of thermodynamics prove that time cannot run backwards, how self
organizing systems challenge the concept of entropy, why it is that we don't
really "know" scientific truths, how mathematics so successfully
describes our world. He will also introduce you to bizarre concepts such as:
Energy and matter are really the same thing; space and time are really illusions;
our universe may be just one of a near infinity of universes; information
content is irrelevant to information management. All in all, a
thought-provoking series of lectures.