In July 2023 a group of lawmakers in the US held a session to explore evidence of extra-terrestrial life. The evidence included the famous Tic Tac videos of mysterious objects flying through the sky.

Pilots described encounters with Unidentified Anomalous Phenomenon – or UAPs. Congress also heard of a secret US government programme that retrieves and reverse engineers materials made by non-humans, including crashed and intact craft – and possibly the remains of the entities that piloted them.

So does this mean we are not alone in the universe? Do sightings and hearsay provide enough scientific data to answer a question that has been asked by humans for thousands of years – are we alone in the universe?

Contributors: Greg Eghigian is professor of history and bioethics at Penn State University in the US. Leslie Kean is an investigative reporter. Adam Frank is Professor of Astrophysics at the University of Rochester, and author of The Little Book of Aliens. Dr Chelsea Haramia is a member of the UK SETI Research Network Post-detection Hub.

Presented by Charmaine Cozier Produced by Louise Clarke Researched by Matt Toulson and Bisi Adebayo Editor Tom Bigwood Mixed by Kelly Young

(UFO crash site sign in Roswell, New Mexico USA / Getty Images)