Disorder, or entropy, in a microscopic quantum system has been measured by an international group of physicists. The team hopes that their feat will shed light on the "arrow of time": the observation that time always marches towards the future. Their experiment involved continually flipping the spin of carbon atoms with an oscillating magnetic field and links the emergence of the arrow of time to quantum fluctuations between one atomic spin state and another.
"That is why we remember yesterday and not tomorrow," explains group member Roberto Serra, a physicist specializing in quantum information at the Federal University of ABC in Santo André, Brazil. At the fundamental level, he says, quantum fluctuations are involved in the asymmetry of time.
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