Neuroscientist Sergiu P. Pasca has made it his life's work to understand how the human brain builds itself -- and what makes it susceptible to disease. In a mind-blowing talk laden with breakthrough science, he shows how his team figured out how to grow "organoids" and what they call brain "assembloids" -- self-organizing clumps of neural tissue derived from stem cells that have shown the ability to form circuits -- and explains how these miniature parts of the nervous system are bringing us closer to demystifying the brain.

Your closet is likely full of all kinds of materials -- leather, cotton, nylon and polyester, to name a few -- that contribute to fashion's sustainability crisis. Biomaterials investigator Dan Widmaier explains how we could look to nature for sustainable replacements for these much-used materials and introduces a leather alternative made from mushrooms that looks great and doesn't harm the environment. "We can make fashion sustainable, and we're going to do it with science," Widmaier says.

The universe that we know, with its luminous stars and orbiting planets, is largely made up of elements we can't actually see -- like dark energy and dark matter -- and therefore don't fully understand. Theoretical physicist Chanda Prescod-Weinstein takes us inside the search for this cosmos-shaping invisible matter and explains how, with the help of a new generation of telescopes, we could be closer to demystifying it than ever before. "The universe is more queer and fantastical than it looks to the naked eye," she says. (If you want to hear more from Prescod-Weinstein, check out her episode on "The TED Interview" podcast.)

A curious, quiet revolution of sound has taken over the internet. Physiologist Craig Richard explains the soothing brain science of Autonomous Sensory Meridian Response (ASMR), tracking its rise in popularity and why this fascinating phenomenon is so relaxing to millions of people around the world.

Linking together the histories of Henrietta Swan Leavitt, Edwin Hubble and Tracy K. Smith, poet and thinker Maria Popova crafts an astonishing story of how humanity came to see the edge of the observable universe. (Followed by an animated excerpt of "My God, It's Full of Stars," by Tracy K. Smith)

The secret behind medicine that uses messenger RNA (or mRNA) is that it "teaches" our bodies how to fight diseases on our own, leading to groundbreaking treatments for COVID-19 and, potentially one day, cancer, the flu and other ailments that have haunted humanity for millennia. RNA researcher Melissa J. Moore -- Moderna's chief scientific officer and one of the many people responsible for the rapid creation and deployment of their COVID-19 vaccine -- takes us down to the molecular level, unraveling how mRNA helps our bodies' proteins maintain health, prevent disease and correct errors in our genetic code. "We have entered an entirely new era of medicine," Moore says.

Building a pandemic-free future won't be easy, but Bill Gates believes that we have the tools and strategies to make it possible -- now we just have to fund them. In this forward-looking talk, he proposes a multi-specialty Global Epidemic Response and Mobilization (GERM) team that would detect potential outbreaks and stop them from becoming pandemics. By investing in disease monitoring, research and development as well as improved health systems, Gates believes we can "create a world where everyone has a chance to live a healthy and productive life -- a life free from the fear of the next COVID-19."

Given the scale of the challenge, the conversation around climate change is often tinged with doom and gloom. But climate tech investor Gabriel Kra thinks we need to reframe the crisis as a source of tremendous opportunity. He offers five big reasons to be optimistic about climate -- starting with the fact that many of the world's best minds are focused and working on building a clean future for all.

Under the sea, untold wonders await in the form of untapped medicinal potential. Chemist Sam Afoullouss dives into the science behind natural remedies, explaining why the ocean's great (and still largely unexplored) biodiversity is ideal for deriving and inspiring future treatments -- if we protect its waters and the marine life within them.

Scientists have long known that cows are a huge source of the greenhouse gas methane, contributing up to four percent of emissions globally. But could there be a way to make cattle less -- ahem -- gassy? Animal scientist Ermias Kebreab talks through an ingenious solution to reduce methane-rich cow burps by feeding cattle something growing below the surface of the ocean: seaweed.