Hannah and Dara tackle a disarmingly simple question: is anything in the universe truly invisible? After ruling out mysterious Nordic spirits and ‘Dara’s ire’, our curious duo start to track down the invisible waves all around them. Including, it turns out, some which are emanating from their VERY OWN FACES! An infrared camera reveals Hannah’s nose as a particular hotspot.

Turning their gaze to bigger things, they wonder: what does our own galaxy look like when viewed in this invisible spectrum? Infrared reveals vast loops and whorls of dust and gas - gigantic structures otherwise totally hidden. But there are even cooler surprises. Ever wondered what an X-ray of the universe looks like? Turns out it’s a sparkly map of white-hot black holes!

Back on earth, the discussion turns to ways of making objects disappear by bending light in tricksy ways. But why is the fancy science of ‘metamaterials’ still struggling to make a proper invisibility cloak? Sorry, Harry Potter fans.

In the end, our physicists reveal a universe bursting with even more elusive, even more mysterious stuff: dark matter and dark energy. Prepare to see the unseen in a whole new light!

Contributors:

Matthew Bothwell - the Public Astronomer at the University of Cambridge and author of The Invisible UniverseAndrew Pontzen - Professor of Physics at Durham UniversityMitch Kenney - Assistant Professor in metamaterials at the University of Nottingham

Producer: Ilan GoodmanExecutive Producer: Sasha FeachemA BBC Studios Audio Production