Comment by Cockbrand

I’ll never stop being fascinated by how neatly all of this fits together: take a hollow cube that has 10cm long edges. Fill it with water - now you have a liter of water. It weighs 1kg. Put it into the freezer, when it just starts freezing, it’s 0°C. Put it onto a stove, and when it starts boiling, it’s 100°C. Simple as that.