A wheel that spins forever; a bird that never quenches its thirst; a clock that never stops ticking, an endless source of free energy. These are but the dreams of inventors striving to make perpetual motion machines, machines that can work forever without any energy input. Are these machines possible without violating the laws of physics? No. Support Physics Girl videos → https://www.patreon.com/physicsgirl ‪http://physicsgirl.org/ ‪http://twitter.com/thephysisgirl ‪http://facebook.com/thephysic

Most-viewed video of 2017: Why don't perpetual motion machines ever work? #10YearsofTEDEd* Perpetual motion machines — devices that can do work indefinitely without any external energy source — have captured many inventors’ imaginations because they could totally transform our relationship with energy. There’s just one problem: they don’t work. Why not? *We're counting down to our 10th birthday on March 12 by sharing ten of our most-viewed videos —one published in each year that we’ve been aroun