Matt Parker, comedian and mathematician, shows how four-dimensional shapes appear in a 3D world in this hands-on talk, featuring what is possibly the world's nerdiest knitted hat! Subscribe for weekly science videos: http://bit.ly/RiSubscRibe Buy Matt's book "Things to Make and Do in the Fourth Dimension" - https://geni.us/M2MIA Discover how to make love hearts from Mobius strips, 4D frames from drinking straws and pipe-cleaners, and other maths tricks in this entertaining talk by Matt Parker. Matt explains how to know when someone's throwing a 4D cubes at you and also what happens when your mum knits a three dimensional shadow of a four dimensional donut - to wear on your head, in this fun talk on the challenges of visualising the fourth dimension. Matt Parker was an Australian school teacher before he moved to London where he works as a stand-up comedian and a maths communicator. He writes books, appears on radio programmes and TV shows, contributes to newspapers, makes school visits and gives live comedy shows. This event took place at the Royal Institution on Tuesday 27 January 2015. The Ri is on Twitter: http://twitter.com/ri_science and Facebook: http://www.facebook.com/royalinstitution and Tumblr: http://ri-science.tumblr.com/ Subscribe for the latest science videos: http://bit.ly/RiNewsletter Our editorial policy: http://www.rigb.org/home/editorial-policy