Absolute Zero: Part 1

Today in science class we watched the video Absolute Zero about the cold: what it is, how people perceived it in the past, and some of the unique properties. This documentary is named so because absolute zero is the coldest temperature there is.  There were many interesting facts about how early scientists developed theories on the cold. One of the more strange yet incorrect theories is about calhors, a mysterious "element" in the 1700s which invisibly made things cold. Since then we have developed a long way in our understanding. The cold is the lack of atomic movement; heat is movement. Important inventions such as the refrigeration, flash freezing, steam engine, and air conditioner were all developed by manipulating the temperatures of our surroundings. In modern times scientists strive towards the goal of creating absolute zero, which is not found in nature. Strange properties are attributed to matter when it becomes super frozen. A new state know as Einstein Bose Condensation is where matter is cooled so much it looses "self awareness" or shape. You cans slow down a beam of light using this property. There are still some questions I have regarding this documentary. Is there an absolute hot? If not, then what is the hottest temperature recorded? Do atoms have special properties when they are heated to high temperatures? Do all refrigerators use ammonia? If so, why?