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D. An Efficient Railway System of the Future

Narrator: This is Science Today. Railway systems in the future may have us literally floating on air. Richard Post, a retired Lawrence Livermore National Laboratory physicist developed a way to build trains that levitate above the railway on powerful magnets. Although this idea - called maglev - has been around for a many years, Post was the first to use ordinary, permanent magnets in a simple, efficient way pioneered by a Lawrence Berkeley National Laboratory physicist named Klaus Halbach.

Post: So, on a train car, there would be a flat panel array underneath the train car - these permanent magnets in the Halbach arrays.

Narrator: This maglev system would cancel out magnetic fields above the array panel so passengers wouldn't feel it, but it would concentrate below where it's needed. Once the train is moving fast enough, it will then levitate above a track made of shorted coils stacked together.

Post: And if the power fails to drive the train, it would slow down a very slow speed and settle down onto auxiliary wheels. It's what you call fail-safe or passively stable.

Narrator: For Science Today, I'm Larissa Branin.