Is absolute zero attainable

Answer 1

NO it is not in theory

The coldest temperatures ever to be reached have been in making Bose-Einstein condensates (tiny clumps of super-cold atoms) which requires cooling to something like 200 nano-kelvins -- mere billionths of a degree above absolute zero.

But to go all the way to zero implies complete lack of particle energy. According to the principles of quantum mechanics, there MUST always be some activity representing energy and therefore a temperature above absolute zero. For example, electron-positron pairs may be created out of vacuum.

Answer 2

No, absolute zero is not something we can achieve. The reason lies in a simple idea included in the tird law of thermodynamics. That sets the bar very high, or low, if you prefer.

To take energy out of a system, you have to "surround" it with a system of less energy. That's because it is essential (required!) that there be a "low energy" place for the energy being removed from a system to go. If a system is to be "reduced" to absolute zero, it must have an absoulte zero system around it to have some place for the energy in the system being investigated to go. It's a catch twenty-two situation. And something we cannot do with anything close to the technology we have now. Use the link below to make a quick review of the third law of thermodynamics and how it applies to this situation.