Probably a stupid question, but will we ever have something like a microwave to make things cold? Is there a reason this can't exist?

Melatonin@lemmy.dbzer0.com to Asklemmy@lemmy.ml – 486 points –
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The water creates a better way to transfer heat from the container to the freezer because it has direct contact with the container and replaces the air around it. Yes the water needs to be cooled too, but still the process is way faster because air really is a good insulator for heat. This is why insulating materials for houses e.g. always try to maximize air content (foam, glass wool, styrofoam)

You also get evaporative cooling, as the freezer is a very low humidity environment. This is accelerating the cooling much more than any thermal conductivity the water adds.

The reverse process is why humid air makes your beverages get warm quickly when the water precipitates on a cold can/glass.

N.B. maximize air content while minimising air movement and therefore convection. Otherwise you could just have cavities in your walls for maximum air.