Did you know that we don't know what 85% of the stuff in our Universe is made of? This mysterious 85% is known as dark matter. We can't see it because it doesn't emit or reflect light, but we know it's there because it exerts a gravitational pull on stars and galaxies, and also bends the path of light.

In this podcast we talk to Blake Sherwin about a brand new map of dark matter that has been produced by a consortium of scientists using data from the Atacama Cosmology Telescope which sits high up in the Chilean Andes. Sherwin is part of that consortium, and he is also Professor of Cosmology and Astrophysics the University of Cambridge and a member of the Stephen Hawking Centre for Theoretical Cosmology at Cambridge.

Sherwin tells us how you go about producing a map of something you can't see, in how far the new map solves the so-called crisis of cosmology, and whether we will ever find out what dark matter is made of.

To find out more about dark matter, read Maths in a minute: Dark matter and What is dark matter? And you can find all the details about the research by Blake, his PhD student Frank Qu, and their colleagues in their series of papers here, here and here.

The music in this podcast is by eusa and the track is called Plankton. you can find their music on Soundcloud.