Emily Levesque explores how the most massive stars in the universe evolve and die and how technology is changing the stories we tell about science and the cosmos.

Luvvie Ajayi Jones is a two-time New York Times bestselling author, podcast host and sought-after speaker who thrives at the intersection of humor, media and justice.

Mehret Mandefro is an award-winning producer, writer and director.

Architect William McDonough believes green design can prevent environmental disaster and drive economic growth. He champions “cradle to cradle” design, which considers a product's full life cycle -- from creation with sustainable materials to a recycled afterlife.

Pushing his body through epic cold-water swims, Lewis Gordon Pugh wants to draw attention to our global climate. He's just back from swimming in a meltwater lake on the slopes of Mount Everest.

Sophal Ear leads research on post-conflict countries -- looking at the effectiveness of foreign aid and the challenge of development in places like his native land, Cambodia.

Robin Steinberg is the CEO of The Bail Project, an organization designed to combat mass incarceration in the United States by disrupting the money bail system -- one person at a time. As she says: "I hate injustice and simply can't sit still when I see it."

David Brenner is developing a unique type of light to kill viruses safely.

Sherry Turkle studies how technology is shaping our modern relationships: with others, with ourselves, with it.

Rick Smolan is the co-founder of the America 24/7 and Day in the Life photography series -- and a natural storyteller in many media. His latest books are America at Home and Blue Planet Run.

Natasha Hurley-Walker uses novel radio telescopes to explore the universe at some of the longest wavelengths of light.

Camille A. Brown leads her dance company through excavations of ancestral stories, both timeless and traditional, that connect history with contemporary culture.

José Andrés is a committed advocate of food and hunger issues and is known for championing the role of chefs in the national debate on food policy.

Ivan Coyote believes that a good story can help inspire us to invent a better future.

Jennifer Granick fights for civil liberties in the age of surveillance and powerful digital technology.

Elizabeth White is an author and aging solutions advocate for older adults facing uncertain work and financial insecurity.

Mara Mintzer thrives on engaging children, youth and underrepresented communities in participatory planning, an approach that aims to integrate the views of all community members into designing exemplary communities.

Mitch Zeller leads the US Food and Drug Administration's efforts to reduce disease and death from tobacco use and bring previously unavailable information about its dangers to light.

Gretchen Carlson is a tireless advocate for workplace equality and women's empowerment.

Nora Brown sings ballads and plays traditional old-time music with a heavy interest in eastern Kentucky banjo playing.

Judith Heumann is a lifelong advocate for the rights of disabled people.

Dr. Laura Robinson's scientific mission is to document and understand the processes that govern climate.

As the leader of the Imaging Team on the Cassini mission to Saturn, Carolyn Porco interprets and shares the pictures coming back from this fascinating planet, its rings and its moons.

Dan Dennett thinks that human consciousness and free will are the result of physical processes.

Rana Abdelhamid is an internationally acclaimed community organizer, first-degree black belt, public speaker and social entrepreneur focused on mass mobilization, international solidarity and the empowerment of marginalized communities.

A Tony Award winner, theater producer David Binder is interested in taking performances off the stage.

Jeanne Pinder asks why it's so hard to make sense of US healthcare bills -- and suggests what we might do about it.

William Ury is a mediator, writer and speaker, working with conflicts ranging from family feuds to boardroom battles to ethnic wars. He's the author of "Getting to Yes."

Stacy Smith shows how Hollywood’s homogenous (and overwhelmingly male) culture systematically excludes women and minorities.

TED Fellow Laura L. Dunn advances and enforces victims' rights for survivors of gender violence in campus, criminal and civil legal systems.