Rachel Graham on tracking COVID-19 from its inception to inform public health on Twitter.

Materials scientist Ainissa Ramirez on her new book “The Alchemy of Us.”

Science journalist Lydia Denworth on the evolution, biology, and power of friendship.

Techno-political thriller writer and humanitarian aid worker Malka Older on the Cyber Age.

Netflix’s “The Great Hack” director Karim Amer on how stolen personal data is abused.

Science journalist Jon Gertner discusses his new book “The Ice at the End of the World.”

M.R. O’Connor on “Wayfinding: The Science and Mystery of How Humans Navigate the World.”

Localization Lab’s Dragana Kaurin on protecting refugees, journalists, and activists.

Charles Graeber on “The Breakthrough: Immunotherapy and the Race to Cure Cancer.”

Seth Fletcher on his new book “Einstein's Shadow” and the quest to see the black hole.

Former State Department Advisor Chris Painter on digital security and foreign policy.

Joy Buolamwini of Algorithmic Justice League on facial recognition and AI technology.

New York Times’ Carl Zimmer on his new book “She Has Her Mother’s Laugh” and genes.

William Egginton of Johns Hopkins on his new book “The Splintering of the American Mind”

North Carolina State scientist Rob Dunn discusses his new book “Never Home Alone.

Richard Gingras, VP of News at Google, on journalism, citizenship, and disinformation.

Democracy Works’ Kathryn Peters on election security, voter registration and democracy.

Dr. Alan Stern and Dr. David Grinspoon on their book on Pluto: “Chasing New Horizons.”

" Investigative reporter Julia Angwin on exposing technologies that injure society. "

Oren Harman on his new book “Evolutions: 15 Myths That Explain Our World."