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.
On supporting science journalism
If you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.
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. The first such detection was done by other researchers with two coils, each containing two million turns of wire, and then with a magnetometer “cooled to four degrees above absolute zero,” Wikswo says. This magnetometer is not spy gear—it is a cryogenic instrument designed to keep the rest of the universe out.
To find a heartbeat, a quantum Ghost Murmur tool would have to contend not just with Earth’s magnetic field and magnetic noise from natural and human-made electric currents but also with “the heartbeats of the sheep and dogs and jackrabbits—whatever else is running around out there,” says Chad Orzel, a professor of physics at Union College in New York State and author of How to Teach Quantum Physics to Your Dog. He uses refrigerator magnets to illustrate the weakness of magnetic fields in general. “You have to get the magnet very, very close to the refrigerator before it snaps into place,” he says. “That field drops off very quickly.” Clinical sensors “are usually butted right up against your body ... at a distance of centimeters,” Orzel adds. Even pattern-matching using artificial intelligence, he says, couldn’t find a magnetic signal large enough to identify the presence of a person from kilometers away in a desert. At one kilometer away, the signal would diminish to about one trillionth of the strength.
Bradley Roth, a physicist at Oakland University and author of the 2023 review Biomagnetism: The First Sixty Years, agrees. “People have been measuring the magnetic field of the heart for 60 years, and usually it’s done in a lab with shielding, and it’s done just a few centimeters or a couple inches from the heart, and even then you can barely record it.” A helicopter-borne version, he says, “would be not just a small advance, but it’d be a revolutionary advance from the state of the art.”
Orzel struggles to see how a Ghost Murmur could work. “There is really fascinating work being done using quantum magnetometry to measure heart rates,” he says, and magnetic brain scans can now catch the tiny flickers of firing nerves. “But none of that is something that works over ranges of many miles.”
So why was this a story at all? Orzel has a guess: “Somebody yanking a reporter’s chain,” he says. It could be a “snarky, clever way to say, ‘Of course, I’m not going to tell you how we figured this out’”—or a piece of disinformation “to fool somebody into thinking that we actually have this secret technology.”