Invisible art: Is there more to it than meets the eye?
Invisible: Art about the Unseen 1957 - 2012 brings together works from the past half century that explore ideas related to the invisible and the hidden.
The exhibition includes work by some of the most important artists of our time as well as younger artists who have expanded on their legacy - with works to observe and take part in.
The BBC's Will Gompertz has been to meet the curator who says the art asks us to make a leap of faith.
From 12 June to 5 August, the Hayward Gallery presents Invisible: Art about the Unseen 1957 - 2012