In our Universe, “cold” is really just the absence of heat. There is a minimum temperature: the point at which there is no heat. It is physically impossible to get any colder (defined as zero degrees Kelvin, which is the same as -459 Fahrenheit, or -273 degrees Celsius). There is no such thing as “negative heat”.
But in the other universe, “cold” exists independent of heat. They both exist, as opposing forces. Mages might specialize in fire magic or ice magic, or have some of both.
Given this, I wonder if it means their universe does not have a minimum temperature.
–Notes from a Senior Planeswalker’s Private Journal.