The “caterpillar drive” in The Hunt for Red October allowed the sub to travel virtually undetected through the ocean, but real examples of magnetohydrodynamic drives (MHDs) are rare.

However, they still rely on some form of traditional propulsion, whether it be fuel or electricity. In contrast, magnetic levitation ... Another challenge is vortex damping, a phenomenon where ...

While an antimatter engine is very far off, researching it could yield other discoveries as well.