no, hot water can indeed freeze (i.e. turn into ice) faster than cold water, in the same environment. http://math.ucr.edu/home/baez/physics/General/hot_water.h

no, hot water can indeed freeze (i.e. turn into ice) faster than cold water, in the same environment. http://math.ucr.edu/home/baez/physics/General/hot_water.html http://math.ucr.edu/home/baez/physics/General/hot_water.html explains it well. he addresses your point directiy: [The "impossibility proof"] implicitly assumes that the water is characterized solely by a single number — its average temperature. But if other factors besides the average temperature are important, then when the initially warmer water has cooled to an average temperature of 30°C, it may look very different than the initially cooler water (at a uniform 30°C) did at the start. Why? Because the water may have changed when it cooled down from a uniform 70°C to an average 30°C. It could have less mass, less dissolved gas, or convection currents producing a non-uniform temperature distribution. Or it could have changed the environment around the container in the refrigerator. All four of these changes are conceivably important, and each will be considered separately below. So the impossibility proof given above doesn't work.