Exponentially faster cooling in a colloidal system

Area of Science:

• Thermodynamics
• Non-equilibrium physics
• Colloidal science

Background:

• The Mpemba effect describes the counterintuitive observation that hotter water can freeze faster than colder water.
• Despite historical observations and extensive research, a general consensus on the underlying mechanisms of the Mpemba effect remains elusive.
• Previous investigations have explored various proposed mechanisms, but a unified explanation is still lacking.

Purpose of the Study:

• To demonstrate and investigate the Mpemba effect in a controlled experimental setting using a colloidal system.
• To quantitatively validate a recently proposed theoretical framework for the Mpemba effect.
• To identify generic conditions that accelerate heat removal and thermal relaxation.

Main Methods:

• Utilized a colloidal system immersed in water as a heat bath for controlled thermal quenching experiments.
• Reproducibly demonstrated the Mpemba effect within this colloidal system.
• Compared experimental results with quantitative predictions from a theoretical framework.

Main Results:

• Successfully demonstrated the Mpemba effect in the colloidal system, showing faster cooling for initially hotter samples.
• Observed cooling rates that were exponentially faster than typical scenarios by carefully selecting experimental parameters.
• Results quantitatively aligned with predictions from a recent theoretical model.

Conclusions:

• The Mpemba effect can be observed and controlled in colloidal systems, serving as a model for anomalous relaxation phenomena.
• The study identifies generic conditions necessary for accelerating heat removal and achieving faster thermal equilibrium.
• The findings suggest the Mpemba effect is a prototype for broader anomalous relaxation phenomena with significant technological implications.