Adam Savage makes things and builds experiments, and he uses costumes to add humor, color and clarity to the stories he tells. Tracing his lifelong love of costumes -- from a childhood space helmet made of an ice cream tub to a No-Face costume he wore to Comic-Con -- Savage explores the world of cosplay and the meaning it creates for its community. "We're connecting with something important inside of us," he says. "The costumes are how we reveal ourselves to each other."

Forests don't have to be far-flung nature reserves, isolated from human life. Instead, we can grow them right where we are -- even in cities. Eco-entrepreneur and TED Fellow Shubhendu Sharma grows ultra-dense, biodiverse mini-forests of native species in urban areas by engineering soil, microbes and biomass to kickstart natural growth processes. Follow along as he describes how to grow a 100-year-old forest in just 10 years, and learn how you can get in on this tiny jungle party.

How do you define "nature?" If we define it as that which is untouched by humans, then we won't have any left, says environmental writer Emma Marris. She urges us to consider a new definition of nature -- one that includes not only pristine wilderness but also the untended patches of plants growing in urban spaces -- and encourages us to bring our children out to touch and tinker with it, so that one day they might love and protect it.

Throughout history, speculation has spurred beautiful, revolutionary science -- opening our eyes to entirely new universes. "I'm not talking about science that takes baby steps," says Eric Haseltine. "I'm talking about science that takes enormous leaps." In this talk, Haseltine passionately takes us to the edges of intellectual pursuit with two ideas -- one that's already made history, and the other that's digging into one of humanity's biggest questions with admirable ambition (and a healthy dose of skepticism from many).

Professional Arab women juggle more responsibilities than their male counterparts, and they face more cultural rigidity than Western women. What can their success teach us about tenacity, competition, priorities and progress? Tracing her career as an engineer, advocate and mother in Abu Dhabi, Leila Hoteit shares three lessons for thriving in the modern world.

"I believe that losing my hearing was one of the greatest gifts I've ever received," says Elise Roy. As a disability rights lawyer and design thinker, she knows that being Deaf gives her a unique way of experiencing and reframing the world -- a perspective that could solve some of our largest problems. As she says: "When we design for disability first, you often stumble upon solutions that are better than those when we design for the norm."

Artist Safwat Saleem grew up with a stutter -- but as an independent animator, he decided to do his own voiceovers to give life to his characters. When YouTube commenters started mocking his Pakistani accent, it crushed him, and his voice began to leave his work. Hear how this TED Fellow reclaimed his voice and confidence in this charming, thoughtful talk.

We are embarrassingly unaware of how divided our societies are, and Brexit grew out of a deep, unexamined divide between those that fear globalization and those that embrace it, says social scientist Alexander Betts. How do we now address that fear as well as growing disillusionment with the political establishment, while refusing to give in to xenophobia and nationalism? Join Betts as he discusses four post-Brexit steps toward a more inclusive world.

What caused the war in Syria? Oppression, drought and religious differences all played key roles, but Marwa Al-Sabouni suggests another reason: architecture. Speaking to us over the Internet from Homs, where for the last six years she has watched the war tear her city apart, Al-Sabouni suggests that Syria's architecture divided its once tolerant and multicultural society into single-identity enclaves defined by class and religion. The country's future now depends on how it chooses to rebuild.

John Legend is on a mission to transform America's criminal justice system. Through his Free America campaign, he's encouraging rehabilitation and healing in our prisons, jails and detention centers -- and giving hope to those who want to create a better life after serving their time. With a spoken-word prelude from James Cavitt, an inmate at San Quentin State Prison, Legend treats us to his version of Bob Marley's "Redemption Song." "Won't you help to sing these songs of freedom?"