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If you are too hot, you can easily turn down the air conditioning or even move to an area with a cooler climate. Either way, this will help you to feel cooler since the air around you will help to remove some of the heat from your body.
If you want to keep food cool, you can toss it in the freezer, and a system of compressors and gas will freeze the food by taking the heat from the compartment and moving it outside the appliance.
From a scientific perspective, cooling things down isn’t that complicated. You just have to find a way to remove the heat from the object in question.
While you may measure the temperature of things in your life using degrees Fahrenheit (or, if you aren’t American, Celsius), scientists use a scale called Kelvin. The Kelvin scale is just like Celsius in the difference between degrees, but it begins at zero.
Zero Kelvin means there is absolutely no heat. None. Zero kelvin, however, is really more of a concept than an actual thing because nothing can ever get that cold.
Scientists have worked hard to make things as cold as possible, and they have gotten down to 0.00000000004 K, but getting rid of that last bit of heat is actually impossible according to the third law of thermodynamics. This law was simply explained by Walther Nernst:
“It is impossible for any procedure to lead to the isotherm T=0 in a finite number of steps.”
When removing heat, it is done in a series of steps. Energy causes atoms and molecules to become active and move around erratically. The more energy, the more movement.
As heat is removed, that movement slows down. But it can never get to zero.
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Since you cannot remove all the heat in one step, you can only ever remove a fraction of it. And you can never reach absolute zero by just removing fractions.
It is pretty easy to get hot things to cool down, but as you get closer and closer to absolute zero, it becomes progressively more difficult.
While not a perfect analogy, it can be compared to increasing speed on a cosmic level. Getting from stationary to even thousands of kilometers per second is relatively easy. The closer you get to the speed of light, however, the more energy it would take to go faster. In order to go the speed of light, you would have to have an infinite amount of energy, which is impossible.
Fortunately, however, getting within a billionth of a degree of absolute zero is good enough for practical purposes, so getting to absolute zero is more of a technical dream than anything that needs to be done.
If you thought that was interesting, you might like to read about the mysterious “pyramids” discovered in Antarctica. What are they?