Context:

• Indian scientists have, for the first time, developed supercomputer-based simulations to understand the long-standing paradox of the Mpemba Effect.

Key Points:

• Researchers from Bengaluru (an autonomous institution under the Department of Science and Technology – DST) have, with the help of a supercomputer, developed the first highly detailed simulation of ice formation in water that clearly demonstrates the Mpemba Effect.
• This effect becomes clearly visible under certain specific conditions when the process starts with hot water.
• The Mpemba Effect is not limited to water alone—it can also occur in other substances during the fluid-to-solid phase transition.
• The hydrogen bonds, metastable states, and the dynamics of nucleation (the initial formation of ice) in water play a crucial role in this phenomenon.
• The simulation accounts for the anomalous properties of water (such as maximum density at 4°C and its hydrogen-bond network), which distinguish it from other liquids.

Why is this Achievement Important? : 

• It helps resolve a decades-old scientific controversy using computational methods.
• Such detailed simulations of a complex system like water were not previously possible due to the extremely high computational power required, which is now achievable through supercomputers.
• The study suggests that the Mpemba Effect may be a general non-equilibrium phenomenon, observable in various types of materials.
• In the future, this research may open new applications in cryogenics, food preservation, material science, and quantum systems.

Mpemba Effect:

• The Mpemba Effect refers to the phenomenon in which hot water freezes faster than cold water under certain conditions.
• Discovery: It is named after Erasto Mpemba, a student from Tanzania, who in 1963 observed during a cooking class that a hot milk mixture froze faster than a cold one.
• Historical Background: Although named after Mpemba, this phenomenon had been mentioned centuries earlier by scientists such as Aristotle, Francis Bacon, and René Descartes.

How Does This Effect Work? (Possible Scientific Explanations):

• Evaporation: Hot water evaporates more rapidly, reducing the total amount of water. A smaller volume can freeze faster.
• Convection: Hot water develops stronger convection currents, allowing heat to reach the surface and escape more quickly.
• Dissolved Gases: Cold water contains more dissolved gases, which can slow down the freezing process. Heating drives these gases out.
• Hydrogen Bonding: According to modern research, hydrogen bonds between water molecules expand when heated and then contract rapidly while releasing energy, thereby accelerating the freezing process.

Examples from Daily Life:

• Ice Cream Making: Many confectioners or chefs believe that placing a hot mixture in the freezer can help it freeze faster and better (though this is not ideal for the freezer).
• Ice Trails: In extremely cold regions, people sometimes throw boiling water into the air for entertainment, where it instantly turns into ice.