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Video abstract for the article 'Noninvasiveness and time symmetry of weak measurements' by Adam Bednorz, Kurt Franke and Wolfgang Belzig (Adam Bednorz et al 2013 New J. Phys. 15 023043). Read the full article in New Journal of http://iopscience.iop.org/1367-2630/15/2/023043/article. GENERAL SCIENTIFIC SUMMARY Introduction and background. Noninvasive measurements do not disturb the state of the system. The majority of measurements, both classical and quantum, are invasive. A special class of weak measurements are noninvasive asymptotically. In classical physics, such measurements satisfy time symmetry—time correlation functions are symmetric under time reversal applied to all relevant quantities. However, quantum correlations of noninvasive measurements violate time symmetry. Whether or not non-invasive quantum measurements meet our classical expectation is both of fundamental importance as well as of practical relevance e.g. for quantum control. Main results. We show that the time-reversal symmetry is violated in a generic quantum weak measurement, while satisfying noninvasiveness. We demonstrate this fundamental paradox for a simple two-level system in thermal equilibrium and show that time reversal symmetry is restored in general in the high temperature or long-time limit. Wider implications. Our novel paradox calls into question the noninvasiveness of quantum weak measurements. It also undermines the classical belief in time reversal symmetry, which now needs an experimental verification.