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Ok so please excuse me if the following mental argument is completely ridiculous or obviously flawed :P I was reading about how, even at 0 K (assuming we could experimentally reach such a temperature), there must be some slight particulate motion, because of the uncertainty principle. What about if we have some particles in a closed box that is in a dark vacuum (assuming a complete absence of any energy or light). If we then proceed to cool the particles to 0 K, then wouldn't we have succeeded at violating the uncertainty principle? We know that the speed of the particles is exactly 0 m/s, and we know with 100% certainty that they are in the box; we do not need to observe them to know so.