Supercomputer Simulations Resolve Mpemba Effect in Water

Scientists have achieved a major breakthrough in resolving the long-standing Mpemba effect, the counterintuitive phenomenon where hotter water freezes faster than colder water. Using advanced supercomputer-powered simulations, researchers have for the first time captured this effect during ice formation at the molecular level. The findings, published in “Communications Physics”, offer fresh insights into nonequilibrium physics and open new possibilities for thermal management technologies.

Understanding the Mpemba Effect

The Mpemba effect has intrigued thinkers since antiquity. Aristotle noted in “Meteorologica” that previously heated water can freeze more quickly. The phenomenon was rediscovered in the 20th century by Erasto Mpemba, after whom it is named. Despite decades of experimental and theoretical interest, a clear explanation, especially for water, remained elusive due to the complexity of simulating its phase transitions.

Role of Supercomputer Simulations

Water is notoriously difficult to model because of its complex hydrogen-bond network. This challenge had prevented computational studies from conclusively addressing the Mpemba effect. Researchers from the Jawaharlal Nehru Centre for Advanced Scientific Research, supported by the Department of Science and Technology, overcame this barrier using high-performance supercomputers. They simulated ice formation using realistic water models and compared it with other systems such as Lennard-Jones fluids and Potts models.

Molecular Pathways to Faster Freezing

The simulations reveal that cooling water does not proceed smoothly towards ice. Instead, it can become trapped in intermediate, short-lived molecular arrangements before true ice nucleates. Crucially, water starting at different temperatures gets stuck in these states for different durations. In some cases, hotter water avoids these kinetic traps and follows a faster pathway to nucleation, allowing it to freeze sooner than colder water.

Imporatnt Facts for Exams

• The Mpemba effect refers to hotter water freezing faster than colder water under certain conditions.
• The phenomenon is named after Erasto Mpemba, who rediscovered it in the 20th century.
• It is an example of out-of-equilibrium behaviour in physics.
• Recent studies show the effect can occur in systems beyond water.

Implications Beyond Water

The study demonstrates that the Mpemba effect is not limited to water but can appear during fluid-to-solid transitions in other materials as well. This advances understanding of nonequilibrium phenomena such as material relaxation after sudden temperature changes. The findings could inform improved cooling strategies and offer new perspectives on thermal control in next-generation electronic devices.