Sure, nature created motor proteins used in synthesizing chemical energy and flexing muscles. And scientists have come up with synthetic molecules that do everything from walk down a prelaid path to spin a metal whisker like a helicopter blade. But now researchers from the Netherlands and Switzerland have outpaced them all. The group fashioned what looks like a molecule-sized car, made of a few dozen atoms, with four-wheel drive. The wheels work like molecular ratchets to all spin in a common direction when fed a fuel of energized electrons from a scanning tunneling microscope. The only difficulty is that lots of the cars don't actually work because when deposited on a copper surface they land on their roofs or sides. That, and even the ones that do drive, don't have much room for groceries.
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