Going against the flow

Tea leaves and other particles can sometimes float upstream

By Stephen Ornes, 08:30 AM July 19, 2013

When water flows, anything in it moves too. But not necessarily in the same direction. Sometimes particles can head upstream, scientists now report. In a paper published July 3, they show how tiny tea leaves seemingly defy gravity to move against the flow.

“It’s interesting and very cool,” Eva Kanso told Science News. Kanso, a physicist at the University of Southern California, San Diego, did not work on the study. Indeed, she noted: “I’m going to have my students do an experiment like th...

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