We can't visualise it, but we can still think about it! And there are clever ways of glimpsing what it might look like.
Find out what it means for a shape to have fractional dimension.
We guide you through an exciting recent breakthrough in the world of topology, involving something called the telescope conjecture.
In normal life higher dimensions smack of science fiction, but in mathematics they are nothing out of the ordinary.
How many dimensions are there? In the latest online poll of our Science fiction, science fact project you told us that you'd like an answer to this question. So we asked theoretical physicist David Berman to find out more. We also bring you a range of other Plus articles exploring the question, as well as two articles from FQXi who are our partners on this project. Happy reading!