All Episodes

What forces tend to make objects round? And why is a sphere the most efficient shape an object can take? The answers will lead us across the cosmos.

Just how "thin"—low in density—is the "thin air" out of which a magician produces a rabbit? And if the universe contains components that are even thinner, exactly what does that mean to us?

This is a discussion of different levels of density and the inherent mysteries of this property, along with the ways in which an understanding of density helps us think creatively about the world.

Take a look at black holes, one of the most fascinating topics in the universe—including the ways in which they would kill a human being, how they wreak havoc in the universe, and some provocative new research.

Here is a detailed look at three scenarios for the destruction of our planet: the death of the Sun, the collision of the Milky Way and Andromeda galaxies, and the heat death of the cosmos.

We now know that a deposit of energy sufficient to kill off 50 to 90 percent of all species strikes Earth every 100 million years. This lecture looks at our risks of getting hit by an asteroid and what we can do to avoid it.

Take a break from the death and destruction of asteroids and the end of the universe and wonder, instead, at the enormity of the cosmos and what our place in it might be.

We now know without doubt how the universe began, how it evolved, and how it will end. This lecture explains and defends a "theory" far too often misunderstood.

A synthesis of the greatest discoveries of physics, astrophysics, chemistry, and biology creates a coherent story of the birth and evolution of the cosmos.

The origin of the elements that make up life is one of the most important discoveries in any field in the 20th century, yet underappreciated by the public because it happened over many decades. This lecture presents a step-by-step explanation of the long path to a Nobel Prize-winning idea.

Before 1995, the planets of our own solar system were the only ones we knew about; the total has now passed 100. This lecture discusses the tools and methods being used to find other planets that might be hospitable to human life.

This lecture examines the very real possibility that life exists elsewhere, and speculates about its origins and chemical makeup.