The discussion centers on finding an efficient method to cool one cubic meter of water from 25°C to 10°C. Participants debate the definition of "efficient," considering factors like energy use, speed, and equipment needed. Suggestions include using ice, liquid nitrogen, or simply measuring temperature without actual cooling. Key factors influencing cooling rates include the temperature difference between the water and the coolant, thermal conductivity, and the rate of coolant supply. The conversation emphasizes the need for clarity on what "efficient" means in this context.