WHAT is the perfect swimming stroke? The answer, if you are stuck in a viscous fluid, is to change your shape quite drastically to haul yourself along. This kind of stroke could one day help microscopic robots swim faster and more efficiently through the human body.
To an extremely small swimmer, such as a bacterium, water feels thick and goopy. It is the equivalent of a person trying to swim through peanut butter. At such a small scale it becomes impossible to glide through water like a fish. And as physicists Frank Wilczek and Alfred Shapere discovered in 1989, if…
