Why can we make heat without expunging cold, but not the inverse (make cold without expunging heat)?
In: Physics
In the terms of energy there is no such thing as “cold energy” there is only the presence it absence of energy in the form of heat. We call that absence of energy “cold”. We feel it as cold because energy seeks equilibrium, thus our higher energy body leaks energy into the low energy “cold” object making us in turn feel that loss of energy as the sensation of cold.
So a heater simply supplies heat into an absence of heat “warming up” the object. Air conditioning takes heat and moves it out of an area thus “cooling down” the area. So it’s not that were making hot or cold, we’re actually just moving “hot” around.
Because there is not such thing as expunging cold. Cold is just the relative absence of heat energy. Heat is all there is.
You can use energy of another type to create heat (chemical, electrical, nuclear etc), and that’s just fine. The equation is balanced, the energy just changed forms.
When we make things cold, all we are doing is transferring the unwanted heat energy elsewhere. We cannot just get rid of it, and changing it to another form takes concentrating that heat a lot more than would be practical in most cases.
To make heat is easy, you just need fire. You light wood or natural gas or something on fire. Or even without fire, you take an element and run a lot of electricity through it and it heats up.
Cold doesn’t work that way. You can’t burn something to make cold. You can’t light something on cold. So the way we do it is by using a very cold substance (refrigerant). Refrigerant acts like a heat exchanger.
A pump pumps the refrigerant through coils. The refrigerant then makes the coils super cold. Air is blown past the coils which makes the air cool down. But at the same time, the heat from the air is getting absorbed by the refrigerant. So we continue to pump it until it gets to a radiator and we run air over it to let it release it’s heat. Then pump it back into the coils. It’s a bit more complex than that, because the pump actually compresses the refrigerant and the expansion of the refrigerant is what makes it super cold. Kinda like when you spray a canned duster for a long time and it gets super cold and causes ice to form.
But ultimately, there is nothing natural that causes things to be cold, except the weather.
Interesting thing to note. While most homes do not have these, most business use what is called a heat pump to manage temperatures. A heat pump works on the same principal as an AC. Except in the winter when it’s cold outside and you want to heat up the inside so people are comfortable, they run it in reverse. So the hot “exhaust” is used to heat the building and the cold air is blown outside.
Because heat is a form of energy; cold is merely the absence of it. In a very real sense, heat is something, while cold is nothing (the absence of that something). So you can make something (make heat, by converting other energy to heat), but you can’t make nothing. You can only take the something that exists and move it elsewhere.
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