Did you know that we can only see around 4% of the universe? Since the observable universe spans a distance of more than 93 billion light years it really does make you wonder where the other 96% is. This documentary helps to spread light on this cunning question which is being worked on by scientists across the world using cutting-edge technology at places such as CERN.
The hunt for dark matter started when Vera Rubin who at the time wanted to stay away from mainstream science began to research whether the same forces which hold solar systems together also held galaxies together. The answer almost certainly was no; there was another, much greater force which was doing the work except that it did not interact with regular particles like gravity does. Dark matter cannot be seen or felt, we can only observe its influences by photographing light passing galaxies over billions of light years (also known as gravitational lensing):