Zero is a satisfyingly round number. On the Celsius scale, it’s the pivot point where liquid water decides to become solid ice. This exact freezing point was defined by the Swedish astronomer Anders Celsius in 1742, using the freezing and boiling points of water at sea level.
Think about that for a second. A single degree of temperature change—from 1°C to 0°C—can turn a flowing river into a skating rink. It’s the difference between a splash and a crunch, between rain and snow. It’s practically magic, except it’s just physics doing its thing.
But Wait: It’s Not Always 0°C
Here’s where we drop a little science bomb. Pure water freezes at 0°C, but the water in your tap isn’t pure. Impurities like salt, minerals, and even tiny particles can lower the freezing point slightly. That’s why the ocean freezes closer to -2°C.
And then there’s supercooling. If water is very pure and undisturbed, it can stay liquid down to -40°C. Then, one tiny shake—bam—it instantly turns to slush. It’s the temperature equivalent of a dramatic plot twist.
