Like, I can just rub my hands together and make them hot, but I don’t know how to make stuff colder
In: Physics
Under the right circumstances you _can_ make stuff colder just as easily. It comes down to _thermal conductivity_, and material-material thermal transfer. It comes down to what materials swap thermal energy most efficiently.
When you hold a flame or candle up to a metal thing, the heat byproduct of the chemical reaction going on in the candle is directly transferring to the metal from the excited molecules of the chemical reaction’s waste byproducts and ambient air heated by the reaction as well. Remove that heat and the metal can only transfer the thermal energy into the air – and it turns out air isn’t a very good thermal conductor. Case in point, sticking your hand in a hot oven takes a while to hurt your hand – air doesn’t transfer the heat to things like your hand very well. But metal to hand transfer is really efficient, so when you touch a baking sheet or the side of the oven you get burned (very quick thermal transfer).
So if you need to heat something very fast (but only up to 100^o C) you’ll do it faster if you boil some water and put the thing in the hot water – water transfers heat much better.
Likewise if you want to cool something quickly, yes, you can put it in your freezer, but unless its resting on something that is already cold, the heat in your thing will transfer slowly to the cold air of the fridge. To speed things up, wet a towel with water and wrap your thing in that, then make sure the towel makes contact with the sides of the freezer. The water will lose its thermal energy to the sides of the freezer very fast and in turn absorb the thermal energy of your thing a lot faster than the cold air will. So pro-tip, if your beer is warm, dunk it in a sink of ice water, or wrap it in a wet towel before you put it in the freezer.
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