system
Given the following post, respond as if you're commenting on Reddit:
human
How does salt lower the temperature of ice water?

I know that salt water has a lower freezing temperature than water, but I don't understand how adding salt to ice water (such as when making ice cream by hand) lowers the temperature of the ice past 0° C without additional cooling.
gpt
When you add salt to ice at 0 C, its freezing point drops...to up to -21 C, depending on the salt concentration.

However, when water melts, it absorbs heat...a lot of heat.  This is known as the latent heat of fusion, and occurs whenever something transitions from solid to liquid.  For water, it takes 80 times the heat to change ice to water as it does to raise it 1 degree C.

So in order to melt 1g of salt water, 80g of water has to get 1 C colder.  With a well designed ice cream maker, a lot of this heat will come from the cream, and you'll get frozen goodness.