Time Can Actually Flow Backward, Physicists Say
Stav Dimitropoulos - 12h ago
Isaac Newton’s picture of a universally ticking clock more or less sums up how we understand time: the arrow of time only moves forward, cruelly robbing us of the chance to revisit our past.
Not everyone takes that for granted though, as evidenced by Albert Einstein, whose 1905 theory of special relativity stated that time is an illusion that moves relative to an observer. Today, physicists like Julian Barbour, who has written a book on the illusion of time, say change is real, but time is not; time is only a reflection of change. And just last week, a team of physicists published a new paper suggesting that quantum systems can move both forward and backward in time.
To understand why scientists previously established that time knows only one direction—forward—we need to examine the second law of thermodynamics. It states that within a closed system, the entropy of the system (that is, the measure of disorder and randomness within the system) remains constant or increases. If our universe is a closed loop, curled up like a ball, its entropy can never decrease, meaning the universe will never return to an earlier point. But what if the arrow of time looked at phenomena where entropy changes are small?
“Take the case of a gas in a vessel,” says Giulia Rubino, a postdoctoral research fellow at the University of Bristol, and lead author of the new paper that appears in Communications Physics. “Let’s suppose that at the beginning, the gas occupies only half of the vessel. Then imagine that we remove the valve that confined it within half of the vessel, so that the gas is now free to expand throughout the vessel.”
More:
https://www.msn.com/en-us/news/technology/time-can-actually-flow-backward-physicists-say/ar-AAWuywv?li=BBnbfcL
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