The growth of physics from philosophy; questions about the nature of reality got answers starting in the Scientific Revolution; the philosophy of physics is energized by the logical positivism movement; the movement spurs new philosophical ideas.

Manipulating numbers giving insight into how the world works; this question by Eugene Wigner; his 1960 paper, "The Unreasonable Effectiveness of Mathematics in the Natural Sciences"; Max Tegmark's assertion that the world is a mathematical system.

Professor Gimbel probes what makes some explanations scientific; whether physics explains anything; Bertrand Russell's rejection of the notion of cause, Carl Hempel's account of explanation; Nancy Cartwright's skepticism about scientific truth.

What is left when one takes all the matter and energy out of space; either something or nothing; Newton believes the former; Leibniz believes the latter; Einstein is influenced by Leibniz's relational picture of space; special theory of relativity.

The laws of physics; one never sees time running backwards; theorists propose that the direction of time is connected to the order of the early universe; Einstein deepens the mystery with his theory of relativity; the possibility of time travel.

Exploring time by winding back the clock; Einstein's initial equations of general relativity predict a dynamic universe; Einstein discards this idea, but since then evidence mounts for a Big Bang; what causes the Big Bang; what happens before.