Explore the biggest mysteries of the Universe with the Unknowns podcast, hosted by historian David Christian, founder of the discipline of Big History. From our cosmic origins in the Big Bang to the furthest reaches of humanity’s possible futures, listen in on expert conversations and unravel unanswered questions about life, the cosmos, and our place within it. Unknowns is the perfect companion for curious minds seeking deep insights and fresh perspectives. Episodes drop every other week, so subscribe now on Apple, Spotify, or your preferred podcast app and begin your dive into the unknown!

Episode 1: Origins of the Universe

Do we know how the Universe began? Sort of…In this episode of Unknowns, historian David Christian and astrophysicist Orsola de Marco explore what we know about the origins of the Universe and the many questions that remain. Unravel the mysteries of existence, from the birth of the cosmos to the origins of life. Perfect for curious minds seeking big answers! 

Publication date: July 25, 2025

Episode 2: Origins of Life

How did we get here? Where are we headed next? In this episode of Unknowns, historian David Christian and biologist Michael Gillings delve into the leading theories on the origins of life and tackle the big question: could there be life on other planets?

Publication date: August 8, 2025

Episode 3: Human Origins

There’s a lot we don’t know about human evolution. Historian David Christian and paleontologist Michael Archer dive into our origins and speculate on the future of our species. Explore the gradual journey from early hominins to modern humans, and the milestones that shaped us.

Publication date: August 22, 2025

Episode 4: Origin Stories

What can we learn from ancient stories? A lot, it turns out! In this episode, historian David Christian and research fellow Lynne Kelly explore global origin stories and what they reveal about where we come from and where we are headed. Discover how ancient narratives connect us, shape our understanding, and influence how we see the Universe.

Publication date: September 5, 2025

Episode 5: The Future of Space Exploration

While we can’t predict the future, we can make some educated guesses about life beyond our planet. In this episode, historian David Christian and astrobiologist David Flannery, an expert in ancient ecosystems and Mars exploration, explore how new innovations like NASA’s Mars 2020 Rover are helping to unlock this mystery. 

Publication date: September 19, 2025

Episode 6: Over a Decade of Big History

Big History has been asking big questions for more than 10 years, what have we learned along the way? In this episode, Big History teacher Kim Lochner chats with David Christian about the past, present, and future of Big History. Big questions. No easy answers. 

Publication date: October 3, 2025