[Retweeted] MILITARY SUBMARINES WON'T BE ABLE TO HIDE MUCH LONGER. QUANTUM IS THE REASON. A submarine's steel hull bends Earth's magnetic field, leaving a disturbance that trails it through the water. Navies have hunted subs with magnetometers since World War II, but the sensors were so weak an aircraft had to pass almost directly overhead to notice. Quantum magnetometers change that. Atomic and superconducting sensors read magnetic fields at sensitivities classical instruments can't approach...