There are many theories in particle physics that cannot be tested in experiments. Does this make it unscientific? This debate, featuring one of our favourite theoretical physicists, David Tong, explores the question.
If you roll a parabola along a straight line then the shape its focus traces out as it goes is ... a catenary!
Why do diamonds sparkle? Where is the 4th dimension in Dali's paintings? Find out the answer to these and 98 other questions about maths and art at John Barrow's talk to launch his new book.
Happy tenth birthday to Maths Inspiration – the fantastic project that has delivered interactive maths shows to over 100,000 teenagers!
Our image of the week shows the courtyard of the British Museum in London with its beautiful glass and steel roof.