A puzzle posted in an online community unlocked a wormhole within the basic shape. Credit...Ian Henderson Supported by By Siobhan Roberts Lisanne Taams, a student at Radboud University in the ...

Opposite sides of a rectangle are equal in length.

In mid-March, the mathematicians Joshua Greene and Andrew Lobb found themselves in the same situation: locked down and struggling to adjust while the COVID-19 pandemic grew outside their doors. They ...