Cooling Methods to Reach Absolute Zero ```Name: Jordyn Status: student Age: N/A Location: N/A Country: N/A Date: N/A ``` Question: I understand that absolute zero temperature cannot be reached because it cannot be measured. However in regard to experimenting with something like this, how would it be possible to cool something to such low temperatures in an attempt to get as close as possible to -273 K (or absolute zero temperature? Replies: Jordyn, There are several laws in Thermodynamics that relate absolute temperature (K) to other physical properties that can be measured or controlled. These laws are a good approximation to the behavior of many gases. Some laws apply to ideal gases and other versions apply to non-ideal gases. For the most part, the relationship between Pressure, Volume and Temperature are all the same for the properties of gases, and that is: The pressure of a gas of a known mass, at a fixed volume, is directly proportional to the gas's absolute temperature. The ideal gas law, for example: PV = nR T, where P is the absolute Pressure, V is the volume, T is the absolute temperature, and n is the known quantity or mass, and R is the universal gas constant. What is important here is to see the relationship between, Pressure and Temperature. If we are to conduct an experiment in absolute temperatures near absolute zero, we may do so in a closed environment, with a gas at a fixed volume. By lowering the absolute pressure to near zero Pascals, we may achieve an environment with absolute temperatures near absolute zero. Hope that helps. Alex Viray Hi Jordyn, Laser cooling is a class of methods used to reach temperatures very close to absolute zero. Here's a good intro to how laser cooling works: http://www.colorado.edu/physics/2000/bec/lascool1.html Also, I might modify your opening statement slightly -- In the case of absolute zero, thermodynamic theory states that absolute zero cannot be reached through thermodynamic methods -- that's different than saying absolute zero cannot be reached because we cannot measure it. (also, I think you mean -273C... 0K is absolute zero, not -273K) Hope this helps, Burr Zimmerman Click here to return to the Physics Archives

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