  Uncertainty relations state that there exist certain incompatible
measurements, to which the outcomes cannot be simultaneously predicted. While
the exact incompatibility of quantum measurements dictated by such uncertainty
relations can be inferred from the mathematical formalism of quantum theory,
the question remains whether there is any more fundamental reason for the
uncertainty relations to have this exact form. What, if any, would be the
operational consequences if we were able to go beyond any of these uncertainty
relations? We give a strong argument that justifies uncertainty relations in
quantum theory by showing that violating them implies that it is also possible
to violate the second law of thermodynamics. More precisely, we show that
violating the uncertainty relations in quantum mechanics leads to a
thermodynamic cycle with positive net work gain, which is very unlikely to
exist in nature.
