Observing Monopoles in a Magnetic Analog of Ice

This is a nontechnical Perspective commentary on two recent neutron scattering experiments (Science 326, 415 (2009) and Science 326, 411 (2009)) reporting evidence for the validity of a "Coulomb phase" description of the low-temperature regime of frustrated spin ice magnetic materials as well as the existence of topological defect (monopole-like) excitations in these systems.