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... On Monday afternoon President Donald Trump and CIA Director John Ratcliffe hinted at technology that had helped locate a downed American Air Force officer hiding in a mountain crevice in southern Iran.
By Tuesday, the New York Post reported that the CIA had deployed Ghost Murmur, a device that uses vaguely described "long-range quantum magnetometry" to find signals of human heartbeats, after which artificial intelligence software isolates each heartbeat from the noisy data. An unnamed source told the Post it was like "hearing a voice in a stadium, except the stadium is a thousand square miles of desert." Another line landed like a movie tagline: "In the right conditions, if your heart is beating, we will find you."
It's a terrific story.
It is also, according to scientists who study magnetic fields, almost certainly not true. The rescue was real -- the mission involved multiple aircraft and a survival beacon carried by the airman -- but Ghost Murmur, at least as publicly described, finds no support in decades of peer-reviewed physics, even with the help of AI, experts told me.
Quantum magnetometers are real; they are ultraprecise at, for instance, detecting heart arrhythmias by measuring magnetic fields (via quantum properties) produced by the cardiac muscle.
The problem is that the heart's magnetic field is weak. "At the surface of the chest, where you're about 10 centimeters away from the source, the magnetic field is just barely detectable," says John Wikswo, a professor of biomedical engineering and physics at Vanderbilt University. "Now, [if] instead of going 10 centimeters away -- which is a tenth of a meter -- you go a meter away, the amplitude of the signal has dropped to a thousandth of what it was." The signal becomes dramatically weaker at a kilometer.
Wikswo was the first scientist to measure the magnetic field of an isolated nerve and has been measuring the heart's magnetic field since the mid-1970s. ...
