There is something mysterious, even a little unsettling, about magnetism, which is why magnets are such great toys for kids and so lucrative for charlatans. But magnetism has also provided a great deal of amusement for serious-minded folks who, over the course of time, have put it to work in countless ways. In the 19th century, scientists discovered that magnetism could be used to generate electricity, create electric motors, and transform voltages. Developments in the 20th century included magnetic memory, magnetic resonance, and magnetic medical imaging. Magnetic fields, researchers found, can also separate isotopes in cyclotrons and mass spectrometers, direct charged particles in accelerators, and levitate trains. Given all those applications, it seems remarkable that magnetism still has a few tricks up its sleeve.
In our lab, the two of us use magnetism to make fluids flow, often in striking ways. Such noncontact flow eliminates the need for motors and...
