Most substances contract when they freeze, so why does water expand as it transitions from the liquid phase to the solid phase?
Fun fact! The 2016 Nobel Prize in Physics was awarded for work related to unusual phase transitions and states of matter.
This was a question from the #MendeleyWall, a giant wall in the Mendeley booth at the New Scientist Live conference where people wrote down the questions they had for science.
Illustrated by Claudia Stocker (vividbiology.com), edited by Lisa Dennison of Science Sketches, background music by Jeff Woodruff of Science Sketches.