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Technology / Re: Is there a device to freeze my drink asap?
« on: 03/03/2021 01:44:30 »
Yes, it is almost always easier to heat something up than cool it down (and it's because of thermodynamics, and what we can do to accomplish each).
Essentially the only way to cool something down is to move its thermal heat elsewhere. The efficiency at which this can be done depends on the temperature of the thing that's getting cooled down, and the temperature of whatever is accepting the thermal energy. (It is spontaneous and really efficient if the object losing heat is much hotter than the heat sink, and the efficiency drops off as they get closer in temperature. Once the source of the thermal energy is colder than the sink, the process is non-spontaneous and requires input of energy (refrigeration). And in this regime, the larger the difference in temperature, the more applied energy is required to move the same amount of thermal energy "the wrong way".
When heating an object up, we can do it by heat transfer (and the same rules apply: it is easy to move heat from hot to cold, not the other way). Or we can transform non-thermal energy into thermal energy (it is much harder to go the other way). One can easily and rapidly generate arbitrarily large amounts of heat in arbitrarily small spaces by delivering electrical energy (think of a light bulb filament that goes from 300 K to 3000 K in the blink of an eye), or chemical energy (like a blowtorch or a combustion engine), or even light energy (concentrated laser light or sunlight can deliver millions of watts per square meter, and instantaneously turn any matter in the focus into a superheated plasma).
Unfortunately there really isn't any good way to have an object at any reasonable temperature cool down significantly by emitting intense light.
Essentially the only way to cool something down is to move its thermal heat elsewhere. The efficiency at which this can be done depends on the temperature of the thing that's getting cooled down, and the temperature of whatever is accepting the thermal energy. (It is spontaneous and really efficient if the object losing heat is much hotter than the heat sink, and the efficiency drops off as they get closer in temperature. Once the source of the thermal energy is colder than the sink, the process is non-spontaneous and requires input of energy (refrigeration). And in this regime, the larger the difference in temperature, the more applied energy is required to move the same amount of thermal energy "the wrong way".
When heating an object up, we can do it by heat transfer (and the same rules apply: it is easy to move heat from hot to cold, not the other way). Or we can transform non-thermal energy into thermal energy (it is much harder to go the other way). One can easily and rapidly generate arbitrarily large amounts of heat in arbitrarily small spaces by delivering electrical energy (think of a light bulb filament that goes from 300 K to 3000 K in the blink of an eye), or chemical energy (like a blowtorch or a combustion engine), or even light energy (concentrated laser light or sunlight can deliver millions of watts per square meter, and instantaneously turn any matter in the focus into a superheated plasma).
Unfortunately there really isn't any good way to have an object at any reasonable temperature cool down significantly by emitting intense light.