What is color? It seems like a simple question at first, but when you think about it, the reality of what we’re seeing is a pretty complex situation. Our human eyes sift through a small piece of the vast electromagnetic spectrum and translate it into every color of the rainbow.

Nowadays, the tools for tracing your family tree have advanced far beyond looking back at names in the family Bible or compiling a scrapbook of paper records. Using your genetic information to find long-lost relatives is easier and cheaper than ever before—and scientists are looking to push the technology even further by analyzing our skin and facial features.

Marcia Bartusiak joins Kip Thorne, Laura Danly and Rainer Weiss to demonstrate how two observatories on opposite sides of the country, called LIGO (Laser Interferometer Gravitational-wave Observatory), may open a new window on observing the cosmos—one based not in light but in gravity.

Probability is the backbone of science, but how well do you understand it? Odds are, not as well as you think; it is a surprisingly subtle concept that is often misunderstood, sometimes even by professionals who use it to guide crucial and far-reaching decisions.

This program, Ending the Epidemic: Science Advances on AIDS, brings together leading researchers on the forefront of scientific efforts to understand and attack the virus that causes AIDS. Moderator Richard …

We spend a third of our lives asleep. Every organism on Earth—from rats to dolphins to fruit flies to microorganisms—relies on sleep for its survival, yet science is still wrestling with a fundamental question: Why does sleep exist?

It’s an old question: What is consciousness? Today, sophisticated brain imaging technologies, clinical studies, as well as the newfound ability to listen to the whisper of even an individual nerve cell, are bringing scientists closer than ever to the neurobiological basis of consciousness.

A self-driving car has a split second to decide whether to turn into oncoming traffic or hit a child who has lost control of her bicycle. An autonomous drone needs to decide whether to risk the lives of busload of civilians or lose a long-sought terrorist. How does a machine make an ethical decision?