Rank #1: Where did the Moon come from? A new theory | Sarah T. Stewart
The Earth and Moon are like identical twins, made up of the exact same materials -- which is really strange, since no other celestial bodies we know of share this kind of chemical relationship. What's responsible for this special connection? Looking for an answer, planetary scientist and MacArthur "Genius" Sarah T. Stewart discovered a new kind of astronomical object -- a synestia -- and a new way to solve the mystery of the Moon's origin.
Rank #2: How a new species of ancestors is changing our theory of human evolution | Juliet Brophy
In 2013, a treasure trove of unusual fossils were uncovered in a cave in South Africa, and researchers soon realized: these were the remains of a new species of ancient humans. Paleoanthropologist Juliet Brophy takes us inside the discovery of Homo naledi, explaining how this mysterious ancestor is forcing us to rethink where we come from -- and what it means to be human.
Rank #3: The age of genetic wonder | Juan Enriquez
Gene-editing tools like CRISPR enable us to program life at its most fundamental level. But this raises some pressing questions: If we can generate new species from scratch, what should we build? Should we redesign humanity as we know it? Juan Enriquez forecasts the possible futures of genetic editing, exploring the immense uncertainty and opportunity of this next frontier.
Rank #4: Can we solve global warming? Lessons from how we protected the ozone layer | Sean Davis
The Montreal Protocol proved that the world could come together and take action on climate change. Thirty years after the world's most successful environmental treaty was signed, atmospheric scientist Sean Davis examines the world we avoided when we banned chlorofluorocarbons -- and shares lessons we can carry forward to address the climate crisis in our time.
Rank #5: What sticky sea creatures can teach us about making glue | Jonathan Wilker
What if we could harness the sticking powers of sea creatures like mussels, oysters and barnacles, which refuse to budge even on wet, stormy coastlines? Dive into the wonderful world of animals that make their own glue and cement with scientist Jonathan Wilker -- and preview some of the amazing things we can learn from how they do it.
Rank #6: The biology of gender, from DNA to the brain | Karissa Sanbonmatsu
How exactly does gender work? It's not just about our chromosomes, says biologist Karissa Sanbonmatsu. In a visionary talk, she shares new discoveries from epigenetics, the emerging study of how DNA activity can permanently change based on social factors like trauma or diet. Learn how life experiences shape the way genes are expressed -- and what that means for our understanding of gender.
Rank #7: The fascinating science of bubbles, from soap to champagne | Li Wei Tan
In this whimsical talk and live demo, scientist Li Wei Tan shares the secrets of bubbles -- from their relentless pursuit of geometric perfection to their applications in medicine and shipping, where designers are creating more efficient vessels by mimicking the bubbles created by swimming penguins. Learn more about these mathematical marvels and tap into the magic hidden in the everyday world.
Rank #8: The most important thing you can do to fight climate change: talk about it | Katharine Hayhoe
How do you talk to someone who doesn't believe in climate change? Not by rehashing the same data and facts we've been discussing for years, says climate scientist Katharine Hayhoe. In this inspiring, pragmatic talk, Hayhoe shows how the key to having a real discussion is to connect over shared values like family, community and religion -- and to prompt people to realize that they already care about a changing climate. "We can't give in to despair," she says. "We have to go out and look for the hope we need to inspire us to act -- and that hope begins with a conversation, today."
Rank #9: 3 kinds of bias that shape your worldview | J. Marshall Shepherd
What shapes our perceptions (and misperceptions) about science? In an eye-opening talk, meteorologist J. Marshall Shepherd explains how confirmation bias, the Dunning-Kruger effect and cognitive dissonance impact what we think we know -- and shares ideas for how we can replace them with something much more powerful: knowledge.
Rank #10: 100 solutions to reverse global warming | Chad Frischmann
What if we took out more greenhouse gases than we put into the atmosphere? This hypothetical scenario, known as "drawdown," is our only hope of averting climate disaster, says strategist Chad Frischmann. In a forward-thinking talk, he shares solutions to climate change that exist today -- conventional tactics like the use of renewable energy and better land management as well as some lesser-known approaches, like changes to food production, better family planning and the education of girls. Learn more about how we can reverse global warming and create a world where regeneration, not destruction, is the rule.