The conventional wisdom is that liquids are completely disordered and lack nontrivial structure beyond nearest-neighbor distances. Using colloidal suspensions as a model system to probe the structure and dynamics of liquids and glasses in real space and at single-particle resolution, I will present experimental findings that upend this view and reveal that the structural order in these systems is, in fact, unusually rich. In the first part of my talk, I will briefly describe experiments where we will use machine-learning techniques to show that the structure hidden in a glass decides its stability against crystallization [1]. In the second part of my talk, using a recently introduced four-point correlation function, we will show that colloidal liquids have a highly nontrivial structure comprising alternating layers with icosahedral and dodecahedral order that grows with supercooling and governs the particle dynamics [2, 3].

[1] D. Ganapathi, D. Chakraborti, A. K. Sood & R. Ganapathy, Nat. Phys. 17, 114 (2021)
[2] N. Singh, Z. Zhang, A. K. Sood, W. Kob & R. Ganapathy, Proc. Natl. Acad. of Sci. U.S.A. 19, e2300923120 (2023)
[3] K. Mishra, R. Ganapathy & W. Kob (manuscript in preparation, 2024)