In physical science, freezing or solidification is the process in which a liquid turns into a solid when cold enough. The freezing point is the temperature at which this happens. Melting, the process of turning a solid to a liquid, is almost the exact opposite of freezing. All known liquids undergo freezing when the temperature is lowered enough, with the sole exception of liquid helium, which remains liquid at absolute zero and can only be solidified under pressure. For most substances, the mel… (More on Freezing)