(TechnologyReview) MIT’s Technology Review reports that headlines about time machines are a long way off the mark. The trigger for all of these was a Scientific Reports paper with the provocative title “Arrow of time and its reversal on the IBM quantum computer.” In it, the authors claimed to have performed an experiment that opens up lines of research, in their words, toward “investigating time reversal and the backward time flow.”
The paper in question describes a quantum-computing version of such a video running in reverse. That “reverses the flow of time,” in a way. If you’ve never seen it before, it’s kind of neat. It might let you see things—like steam flowing back into a tea kettle or Humpty Dumpty spontaneously assembling from a jumble of broken pieces—that appear to “reverse the arrow of time.”
Scott Aaronson, director of the Quantum Information Center at the University of Texas at Austin, says, “If you’re simulating a time-reversible process on your computer, then you can ‘reverse the direction of time’ by simply reversing the direction of your simulation”.

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