system
Given the following post, respond as if you're commenting on Reddit:
human
Why is −273.15° Celsius Absolute Zero? What's stopping you from going any colder?
gpt
To overly simplify, lets say that a measurement of temperature is, more or less, a measure of how much the atoms in an object are jiggling about. The more they jiggle, the more they hit the things around them and make them jiggle, and the more some of the atoms get jiggled off and go on their own adventures.

Now, temperature can be measured on different scales. Fahrenheit is one, celcius is another... And kelvin is a third. "Absolute zero" is called that in reference to the Kelvin scale, where the lowest temperature is 0 Kelvin. (This is exactly the same as -273.15c, it's just a different way of showing it.) This temperature is where there is no energy in the object, which is to say, no jiggling of the atoms, completely still. So you can't go lower than that temperature for the same reason a stopped car can't slow down: there is no speed to reduce, no energy to lose, no temperature to drop.