A New York Post story claimed the CIA pulled off something out of a Tom Clancy novel. A downed American weapon system officer was hiding, injured, deep in Iranian mountains, and the agency supposedly found him by detecting the faint magnetic field of his beating heart from kilometers away with a device they nicknamed Ghost Murmur. Veritasium takes that claim apart bit by bit. The heart really does make a magnetic field, synthetic diamonds really can sense magnetic fields at room temperature, and the CIA really does use both deception and exotic sensors. But when you run the numbers, the distance kills it.
Published May 3, 202621:18 video19 min readAdded Jun 14, 2026Open on YouTube →
At a glance
A New York Post story claimed the CIA pulled off something out of a Tom Clancy novel. A downed American weapon system officer was hiding, injured, deep in Iranian mountains, and the agency supposedly found him by detecting the faint magnetic field of his beating heart from kilometers away with a device they nicknamed Ghost Murmur. Veritasium takes that claim apart bit by bit. The heart really does make a magnetic field, synthetic diamonds really can sense magnetic fields at room temperature, and the CIA really does use both deception and exotic sensors. But when you run the numbers, the distance kills it. The signal falls off with the cube of distance, and a heartbeat at the range claimed would be roughly a billionth of a billionth of a billionth of a Tesla, about 18 orders of magnitude fainter than the best diamond sensor on Earth can currently read.
This is not a debunking that ends in a shrug. It is a tour through real physics, a real rescue, real quantum sensors, and a real history of intelligence agencies floating beautiful lies to hide ordinary methods. The verdict is that Ghost Murmur is almost certainly fiction, and the most interesting part is what the diamonds are actually good for.
The setup: a rescue that should not have been possible
The video opens on a date. On April 3rd, 2026, Iranian forces shot down an American fighter plane just over Isfahan. Two crew were aboard, a pilot and a weapon system officer, and both ejected successfully. The pilot was found and rescued fast, only seven hours after the crash. The weapon system officer was not so lucky. He came down somewhere else, deep in hostile territory, and he was injured. With Iranian forces hunting him, he hid in the mountains.
He was not without options. He carried a rescue beacon that could broadcast his location to US forces. The catch is the catch every downed pilot faces. To transmit, he had to break cover, and any signal he sent could be intercepted by the people looking for him, who would then reach him first. So he rationed the beacon and stayed hidden, while the enemy closed in by the hour.
Finding one injured man in a desert by brute force is a losing proposition. A blind sweep of that terrain could take days or weeks. Yet just 40 hours after the crash, the US announced he had been rescued. Still invisible to the enemy, the line goes, but not to the CIA. How?
According to the New York Post, the answer was a futuristic device. The agency reportedly detected the magnetic field produced by the man's heartbeat from kilometers away. Pause on what that requires. The device would have to pick one heart out of a landscape full of magnetic noise: other soldiers, vehicles, animals, and Earth's own magnetic field, which dwarfs a human heart by a factor of a million. It is, as the narrator puts it, like listening for a murmur in a crowd. Hence the name the press attached to it, Ghost Murmur.
The story went viral instantly. Clip after clip of people repeating the phrase, calling it science fiction, marveling at it. And almost all of it traced back to a single New York Post article with no corroborating sources. That is exactly the kind of claim Veritasium exists to test, so they dug in, talked to magnetometry physicists and a retired CIA officer, and asked three concrete questions.
Figure 1. The video's structure in one frame. Two of the three premises check out as real physics. The third, the distance, is where Ghost Murmur falls apart.
Question one: does the heart make a magnetic field?
Yes, and the reason is simple electromagnetism. Whenever current flows through a conductor it generates a magnetic field around it. Our bodies run on electrical impulses moving through neurons, so our tissues and organs all produce faint magnetic signals. The heart wins because its muscle fibers fire in a coordinated way, so its field is the strongest in the body. It comes in around 50 to 100 picoTesla, which is 10 to 100 times stronger than the next strongest source, the brain.
Strongest in the body still means almost nothing in absolute terms. The heart's field is about a million times weaker than Earth's own magnetic field. That ratio is the whole problem in one number. It is why the heart's magnetic field, the magnetocardiogram, was not detected until 1963, and why that first detection had to happen in a remote field, far from the magnetic noise thrown off by lab equipment, elevators, and cars. The detector had to sit perfectly still, because even the slightest vibration would corrupt the reading. That is the opposite of a device bolted to a helicopter or a drone.
Figure 2. Everything plotted on a logarithmic ladder. The heart at your chest is already a million times weaker than Earth's field. Push it out to the claimed range and it sinks far below the floor of any sensor humanity has built.
Detectors did improve. By the 1970s came the superconducting quantum interference device, the SQUID. SQUIDs are extraordinarily sensitive, reading fields as faint as a few femtoTesla. The US military, predictably, strapped them to planes and helicopters and tried to spot large magnetic signatures like submarines in the ocean, though that project never really took off. SQUIDs did make heartbeat detection easier, but with a fatal caveat for field work. As one expert explains, they need tightly controlled conditions, often inside shielded rooms, and they cannot cope with a large dynamic range of background fields or electromagnetic interference. Later magnetometers traded one weakness for another, always tripping on shielding, sensitivity, or dynamic range. None of them was practical for catching a heartbeat out in the open.
That dead end is what makes the next character so interesting: a sensor made of diamond.
Question two: how a diamond becomes a magnetometer
Starting in the 1990s, physicists began looking at diamonds that might sense magnetic fields while dodging the old drawbacks. The pitch from the researchers is genuinely exciting. These quantum magnetometers work at room temperature, and they are solid state sensors, which makes them robust and practical in a way a cryogenically cooled SQUID never could be. These are the synthetic diamonds the New York Post named. So how do they actually work? The video builds the answer from atoms up.
The defect that does the sensing
A pure diamond is just an ordered lattice of carbon atoms, and it does not react to magnetic fields in any useful way. The magic comes from breaking it on purpose. Replace one carbon atom with a nitrogen atom, then remove a neighboring carbon entirely to leave a hole. That paired flaw, a nitrogen next to a vacancy, is called a nitrogen vacancy center, or NV center.
The NV center becomes useful when it traps two unpaired electrons. Electrons carry an intrinsic property called spin. The flawed but useful analogy is that spin is a tiny bar magnet giving each electron its own magnetic signature that can point up or down. Expose that electron to an external field and its little magnet either aligns with the field or against it. (A particle with no net spin simply ignores the field.) The two trapped electrons can arrange themselves three ways: both up, both down, or opposite. Those become a spin magnetic quantum number, written ms, of +1, -1, or 0. The whole NV center then behaves like one bar magnet sensitive to the outside world.
Figure 3. The NV center. One carbon becomes nitrogen, the neighbor goes missing, and the resulting defect traps two electrons whose combined spin acts as a single tunable bar magnet, the heart of the sensor.
Reading the diamond with light
So the diamond now responds to magnetic fields. The harder question is how you read that response out, and the answer is light. Shine light at an atom and it either absorbs a photon or ignores it. An absorbed photon kicks an electron up to a higher energy level, and those levels work like discrete platforms in a video game, fixed heights an electron can jump between. In an isolated atom the platforms are sharp. Pack many atoms together in a lattice and the levels smear into closely spaced bands.
An electron only absorbs a photon energetic enough to clear the band gap, the jump from the highest occupied band to the first empty one above it. In pure diamond that gap is big, about 5.5 electron volts, so only ultraviolet photons can make the leap. Visible light lacks the energy and passes straight through, which is exactly why a flawless diamond is transparent. Add defects, though, and you punch secret platforms into the gap, new midway levels electrons can reach with weaker light. A boron defect, for instance, opens a level at just 0.37 electron volts, reachable by infrared and red light. Add enough boron and the diamond eats the red part of the spectrum and ends up looking blue.
The nitrogen vacancy defect opens its own secret platforms, and those are the ones that report on magnetic fields. Look closely at the lowest NV level and it is not one level but three, closely spaced, corresponding exactly to the three ms states. The arrangement makes physical sense. Two bar magnets sitting with one up and one down is the relaxed, lowest energy configuration, the ms = 0 state. Forcing both to point the same way, ms = +1 or -1, costs energy, so those two sit together at a slightly higher level. The gaps are tiny. Jumping from 0 up to the ±1 levels needs only a microwave photon with a wavelength of 10.4 centimeters. These platforms were mapped out by the 1990s, but as one physicist notes, it took a full decade and a real mindset switch before anyone thought to use them as sensors at all.
Zeeman splitting: the actual measurement
Now turn on a magnetic field and watch. As the field strengthens, the +1 and -1 levels start to move apart. The compass analogy nails why. A compass needle naturally aligns with Earth's field, its relaxed low energy state, which mirrors ms = -1, so that level drops slightly. Flip the needle 180 degrees against the field, the way an external magnet can force it, and you can balance it in an unstable high energy position, which mirrors ms = +1, so that level rises slightly. The ms = 0 state does not react to the field at all, so its level stays put. Crank the field higher and the +1 and -1 levels keep spreading. That spreading is called Zeeman splitting, and it follows a simple formula linking the size of the split directly to the field strength.
This is the readout. The two split levels absorb light at two different microwave wavelengths, and the spacing between them tracks the field. With no field, the levels are fused and you see a single absorption line at 10.4 centimeters. With a field, you see two separate absorption lines. Measure how far apart the lines sit and you have measured the magnetic field. In a rhythmic field like a beating heart, you would see the lines rhythmically separate and recombine. That is, in simplified form, exactly how an NV diamond magnetometer works.
Figure 4. Zeeman splitting is the measurement. The ms = +1 and -1 levels start fused, split apart in a field, and the gap widens with field strength. Read the microwave wavelengths the diamond absorbs and you have read the field.
Question three: the distance kills it
Two premises survived. The heart makes a field, and diamonds can read fields. The third premise is where it all collapses. Has an NV diamond ever actually picked up a heartbeat at range?
The honest answers from the literature are humbling. Magnetic fields from neurons were first seen with these sensors around 2015, which is genuinely impressive. The closest anyone has come to a heart was 2022, when researchers picked up the magnetic field of a rat's heart, but only via a thoracotomy, meaning the rat's chest was cut open and the diamond sat less than two millimeters from the heart. The leap from two millimeters against an exposed heart to several kilometers across open desert is not incremental. It is astronomical, and the physics says so precisely.
A magnetic field falls off with the cube of distance from its source. Start with the heart's field at the chest, about 50 picoTesla, or 5 times 10 to the -11 Tesla. Move out to just 100 meters and the cube law slashes it by roughly a factor of a billion, down to 5 times 10 to the -20 Tesla. Push to the 50 to 100 kilometers implied by the story and it sinks to something like 10 to the -30 Tesla.
Set that against the state of the art. The most sensitive measurement ever made at heartbeat frequencies tops out around 10 to the -15 Tesla, and that is inside a shielded room. To read a heart at the claimed range you would need a system about 15 orders of magnitude more sensitive than the best SQUID and about 18 orders of magnitude more sensitive than the best diamond NV sensor. As one researcher put it flatly, 18 orders of magnitude is a lot, and it sounds quite unfeasible.
Field strength (Tesla)
Versus best sensor
Heart at the chest
5 × 10⁻¹¹
readable in a shielded room
Heart at 100 meters
5 × 10⁻²⁰
already below every real sensor
Heart at 50 to 100 km (claimed)
~10⁻³⁰
~18 orders below diamond NV limit
Best heartbeat measurement ever
~10⁻¹⁵
the actual ceiling, in a shielded room
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The cube law is only the start of the trouble. The hills of Iran are not empty. They are full of animals with their own beating hearts, some of them larger than a human's. There is the magnetic field of the drone or helicopter the sensor would ride on, which would swamp everything. And there is a closing absurdity worth sitting with: a field of 10 to the -30 Tesla is weaker than the magnetic field a single electron produces a meter away. You would be hunting for a signal fainter than one lone electron in the next room, across kilometers of noisy desert, from a moving aircraft.
So why does the story exist?
If it is physically impossible, why did so many serious people, including NV diamond researchers, go quiet and decline to comment, sign NDAs, and refuse to engage? The video offers two converging explanations, and neither requires the heartbeat trick to be real.
The first is the long tradition of deception. The retired CIA operations officer, Douglas London, is blunt that the agency leveraging exotic technology fits its mission and charter, but defers on whether this specific technique is real, while noting the New York Post is, in his words, a very good place for amusing fiction. He points out the man could have been found by far more ordinary means, including a beeper mentioned in a separate article the day before, plus other routine intelligence methods. The deeper point is historical. Fooling your enemy to protect a real vulnerability goes back thousands of years. The video's gem of an example is the carrot myth. During World War II, British night fighters kept finding German bombers in the dark, and UK officials told the press it was because the pilots ate lots of carrots that sharpened their night vision. The real reason, experts believe, was airborne radar newly installed on the planes, and the carrot story was a cover to keep the Germans from guessing. That, the video notes, is very likely the actual origin of the carrots are good for your eyes myth we still repeat. A Ghost Murmur that makes Iran fear a magic heartbeat detector, while hiding how the man was really found, would be the same play.
The second explanation is that the diamonds are quietly useful for something else entirely. NV centers in diamond are already a platform for quantum computing. The more intriguing and probably confidential application is navigation. Earth's magnetic field forms a unique fingerprint pattern across the globe, with countless local perturbations and inhomogeneities. A sensitive enough magnetometer that knows the map can place itself on it and infer its position with no GPS at all. In an era of widespread GPS spoofing and jamming, a GPS free navigation sensor is genuinely powerful, and very much the sort of thing an agency would protect with silence. The secrecy is real. It just is not about heartbeats.
The video closes honestly. NV magnetometers with synthetic diamonds do exist, and they do have real military applications. Detecting heartbeats from kilometers away simply is not one of them. It ends with a generous shout-out to a Scientific American piece by Deni Béchard that expressed early skepticism of Ghost Murmur.
Key takeaways
The heart does produce the strongest magnetic field in the body, about 50 to 100 picoTesla, but that is still a million times weaker than Earth's field, which is why it was not detected until 1963.
NV center diamonds are real, room temperature, solid state quantum magnetometers. They sense fields through Zeeman splitting of an electron spin defect, read out optically and with microwaves.
Magnetic fields fall off with the cube of distance. A heartbeat at the claimed 50 to 100 km would be around 10 to the -30 Tesla, roughly 18 orders of magnitude below the best diamond sensor ever built.
That target is fainter than the field of a single electron a meter away, before you even account for animals, Earth's field, and the aircraft's own magnetic signature.
Intelligence agencies have floated beautiful cover stories for millennia. The WWII carrot myth was a cover for airborne radar, and Ghost Murmur fits the same mold.
The diamonds' real, probably classified value is likely GPS free magnetic navigation, which matters enormously in an age of GPS spoofing and jamming.
Chapters
Timestamps are clickable. Click one and the player jumps there and keeps playing while you read. This video has no chapters set by the creator, so these are estimated from position in the narration.
0:00 The downed officer and the impossible rescue
1:30 Enter Ghost Murmur and the media frenzy
2:45 The two clues in the New York Post article
3:30 Question one: does the heart make a magnetic field?
5:00 1963 detection, SQUIDs, and why field work is hard
7:00 Question two: diamonds, NV centers, and electron spin
9:30 Reading the diamond with light and the band gap
12:30 Zeeman splitting: how the measurement actually happens
14:30 Has it ever caught a heartbeat? The rat thoracotomy
15:30 Question three: the cube law and 18 orders of magnitude
17:30 Why agencies lie: the WWII carrot myth
19:30 The real use, magnetic navigation, and the verdict
Notable quotes
It's like listening for a murmur in a crowd. So the technology was appropriately called Ghost Murmur.
Veritasium narrator, 1:35
I very rarely believe things I read in the New York Post. I find it extremely difficult to believe.
Expert interview, 2:20
It's around 50 to 100 pico Teslas, 10 to 100 times more than the next strongest field produced by the brain. But even then, this is still a million times weaker than Earth's magnetic field.
Veritasium narrator, 4:10
There was a decade before the light bulb went on for a bunch of us to think about them as sensors. It takes a mindset switch to think differently.
NV magnetometry researcher, 11:40
18 orders of magnitude is a lot, sounds quite unfeasible.
Veritasium narrator, 16:50
The New York Post is notoriously a very good place for amusing fiction.
Douglas London, 17:30
So NV magnetometers do exist with these synthetic diamonds, and they do have potential military applications. It's just that detecting heartbeats kilometers away probably isn't one of them.
Veritasium narrator, 20:30
Resources mentioned
Veritasium, the channel, presented and written by Gregor Čavlović.
Snatoms, Derek Muller's magnetic molecular modelling kit.
The one thing to walk away with
Ghost Murmur is a great story precisely because every individual piece sounds plausible. The heart really beats out a magnetic signature, diamonds really do read magnetic fields, and the CIA really does both spy and deceive. The trap is that plausibility multiplies into impossibility once you add the distance, because the cube law turns a hospital-grade signal into something fainter than a single electron in the next room. The lesson is not that quantum sensors are hype. They are real and quietly revolutionary, just for navigation rather than for hunting hearts. The lesson is that when a sensational claim rests on one source and a wall of no comment, the most likely explanation is the oldest one in the intelligence playbook. Sometimes the carrots are just radar.
Full transcript
Could the CIA really track your heartbeat from kilometers away?
On April 3rd, 2026, Iranian forces shot down an American fighter plane just over Isfahan. Inside were a pilot and a weapon system officer, and both ejected successfully. The US forces located the pilot quickly and rescued him only seven hours after the crash, but they couldn't rescue the weapon system officer. He landed elsewhere deep within hostile territory. And, worst of all, he was injured. With the Iranian forces on his tail, the officer needed to hide quickly, so he disappeared into the mountains, to rescue an aviator buried deep behind enemy lines.
Fortunately, the officer had a rescue beacon that could signal his location to the US. The problem was that he not only had to step out of his hiding spot to transmit the signal, Iran could potentially intercept it and get to him first. So he could only use the beacon sparingly. With enemy forces getting closer every hour, how is the US going to pinpoint his location in the middle of a desert.
A blind sweep of the entire area could take days or even weeks, but, surprisingly, just 40 hours after the crash, the US announced the officer was rescued. Still invisible to the enemy, but not to the CIA.
So how did they do it? Well, according to a New York Post article, the CIA deployed a futuristic device to rescue him. Reportedly they were able to detect the magnetic field produced by his heartbeat from kilometers away. Such a device would have to overcome the magnetic signatures from other soldiers, vehicles, and animals in the region, let alone Earth's magnetic field. It's like listening for a murmur in a crowd. So the technology was appropriately called Ghost Murmur.
Immediately this kicked off a media frenzy. Ghost Murmur. This is science fiction. Did you hear about what the CIA tech that they have called the Ghost Murmur. Called the Ghost Murmur.
All of this sounds too good to be true, and there seemed to be no other sources beyond this New York Post article. So we dug deep to find out whether this supposed technology really exists and what its limits are.
I very rarely believe things I read in the New York Post. Okay. I find it extremely difficult to believe. Many of these researchers in the NV diamond area, are having to sign NDAs. The fact that the CIA is involved in leveraging technologies consistent with their mission and their charter.
So is Ghost Murmur fact or fiction? There are two lines in this New York Post article that hint at what this device can be. First, normally this signal is so weak that it can only be measured in a hospital setting with sensors pressed nearly against the chest, the source said. But advances in a field known as quantum magnetometry, specifically sensors built around microscopic defects in synthetic diamonds, have apparently made it possible to detect these signals at dramatically greater distances.
We're gonna break this down bit by bit. First, does the heart actually create detectable magnetic fields? Second, what are these synthetic diamonds that could potentially detect them? And third, is it all possible at these distances?
Let's start with a heart. Now, if you type heart magnetic field into Google Images, you will get a bunch of questionable-looking graphs. So is it a real thing? Well, whenever current flows through a conductor, it generates a magnetic field around it. And since our bodies run on electrical impulses traveling through neurons, our tissues and organs generate faint magnetic signals. But because the heart muscles fire in a coordinated way, the magnetic field they produce is the strongest in the body. It's around 50 to 100 pico Teslas, 10 to 100 times more than the next strongest field produced by the brain. But even then, this is still a million times weaker than Earth's magnetic field.
So it's no surprise that we only detected the magnetic field of the heart in 1963. It had to be done in a remote field away from the magnetic noise produced by lab equipment, elevators, and cars. And the setup had to be incredibly still. Even the slightest vibration of the detector would corrupt the measurement, not something that could work on a helicopter or a military drone.
But, pretty soon, magnetometers got better. By the 1970s, we got superconducting quantum interference devices, or SQUIDs. These magnetometers were incredibly sensitive, detecting fields as weak as a few femto Tesla. To no surprise, the US military quickly strapped these SQUIDs to planes and helicopters, and they tried to use them to detect large magnetic signatures like submarines in the ocean. But the project never really picked up. Nonetheless, SQUIDs also made it easier to detect the heart's magnetic field, but with a key caveat.
They typically need to be operated under a very tightly controlled conditions, often inside of shielded rooms. They can't handle large dynamic range of background fields and electromagnetic interference.
Future magnetometers offered solutions, but they also had their own drawbacks. There were always issues with either shielding or sensitivity or dynamic range that made them impractical for detecting heartbeats out in the field. Until the 1990s when physicists started looking into diamonds that might eventually be able to sense magnetic fields while potentially getting around the drawbacks.
These new quantum magnetometers work at room temperature operation, and that's what's really exciting about them. They're also a solid state sensor, which, you know, can be very practical for some applications and can be made into like a more robust kind of sensor.
These are the diamonds mentioned in the New York Post article. So how do they work?
Now, the overall coverage of the story is actually very interesting because this tech is supposedly classified. There's a lot of uncertainty about whether what's being reported is actually real. And depending on which outlet you see first, you might arrive at completely different conclusions. For example, if you saw this headline first, you might be really impressed with the technology, but this one you'd be a bit more skeptical, and the last one might not even make you care about the tech. So three headlines, three completely different conclusions, and that's where today's sponsor Ground News comes in. They're a website and an app designed to make reading the news easier and more data-driven. Each day they round up stories from thousands of outlets all around the world and give you a visual breakdown of the story, including its political leaning, factuality rating, and even ownership, all backed by ratings from three independent media-monitoring organizations. In case of this Ghost Murmur story, you can see that it's been reported on by 65 sources, but the coverage is pretty lopsided. So if you only get your news from right-leaning outlets, there's a chance you've seen the story. But if you only get it from the left, there's a chance you haven't. And below that, you can also see the factuality rating and the ownerships of the sources. They also have this blind spot feature, which highlights stories like the Ghosts Murmur one that were under reported on by either side of the political spectrum. Staying up to date and well-informed with accurate information has almost become a full-time job. And that's where Ground News's approach is so valuable. They make reading the news more digestible and accessible, and you can see all of the information within moments, not hours. So if you, like us at Veritasium, care about getting to the truth, you can go to ground.news/ve or scan this QR code and our link will get you 40% off their vantage plan. So I wanna thank Ground News for sponsoring this part of the video, and now let's go figure out how those diamonds actually detect magnetic fields.
Well, for something to function as a magnetometer, it needs to respond to a magnetic field in a way that we can detect. Now, a pure diamond is just an ordered lattice of carbon atoms, so it doesn't react to magnetic fields in a meaningful way. But this changes when you start adding defects to the lattice. You can replace one of the carbon atoms in the lattice with, say, a nitrogen. And if you remove one of the carbons next to it completely, well, that creates a vacancy. This defect is called a nitrogen vacancy or an NV center.
And these NV centers become particularly useful when they trap two unpaired electrons. That's because electrons have this intrinsic property called spin. A simple and flawed analogy is that spin is kind of like a tiny bar magnet that gives electrons their own magnetic signature and it can point either up or down. So when an electron is exposed to an external magnetic field, this magnetic signature will either align itself with the field or against it. Also note that particles that have no net spin will not respond to an external magnetic field.
Now, the two trapped electrons can arrange their spins in the following way. They could both point up, which would give you a spin magnetic number of 1. They could both point down for a quantum number of -1, or they could point in opposite directions for a quantum number of 0. We'll denote this spin magnetic quantum number with ms, and it essentially acts as a bar magnet for the whole NV center. And just like for individual electrons, this bar magnet is also sensitive to external magnetic fields. So now that we've created a diamond that responds to magnetic fields, the challenge is, how do we measure this response to detect a heartbeat?
Okay, so I reached out to experts to try and figure this out, but basically out of the 20 or so emails that I sent, I only got a few responses, but then I got an impromptu call from one of these experts who said that many of these researchers in the NV diamond area. This is getting a lot more interesting. But with how secretive everyone was being, I had to use publicly available research.
And I think the key idea is to figure out how diamonds respond to magnetic fields, you have to use light. When you shine light at an atom, the atom can either absorb the light or ignore it. An absorbed photon of light will excite an electron within the atom to a higher energy level. You can think of these energy levels as discrete platforms that the electrons can jump between, just like in a video game. All atoms of the same element, for example, carbon, have the same energy levels when the atoms are far enough apart. But when you bring them together, like inside a diamond lattice, their energy levels shift. They come together to form a series of closely spaced energy levels or an energy band.
Now, an electron will only ever absorb a photon if the photon has enough energy to move the electron across the gap to a higher band. This gap between the last electron occupied band and the first empty band above it is called the band gap. In a pure diamond, it's big. It's around 5.5 electron volts, which means that only ultraviolet photons have enough energy to excite the electrons. All lower energy light, including visible light, will mostly be ignored by the diamond and just pass through. This is why a perfect pure diamond is transparent. It doesn't absorb any of the light, but if you start adding defects, they disrupt that organized lattice. The defects unlock different energy levels. Secret platforms within this band gap for nearby electrons to jump to.
A boron defect, for example, creates a low energy level at only 0.37 electron volts. This is a platform that electrons can jump to by absorbing infrared or red light. And with enough boron defects, a significant amount of red light gets absorbed this way. The rest of the visible spectrum mostly makes it through. So without this red, the diamond appears blue.
Similarly, a nitrogen vacancy defect unlocks other secret platforms. And these can help us detect how the NV center responds to a magnetic field. At first glance, it looks like the nitrogen vacancy generates a few unique levels, and these are exclusive to the two unpaired electrons trapped within the defect. But if you look closer at, for example, the lowest level, you'll notice that it actually contains three closely spaced but separate energy levels. The second and third levels are actually at the same height, but will draw them separately. And the fact that there are three isn't a coincidence. Remember, the NV center can adopt one of three ms numbers, 0, -1, or 1, depending on how the spins of the two electrons inside are arranged.
If you think of the two spins as bar magnets, the most relaxed, lowest energy way for them to sit is this, one pointing up and the other down. This is analogous to the ms = 0 state, which is why it has the lowest energy. Forcing both magnets to point down together or up together, like the ms = 1 or -1 states requires more energy. They oppose you. So these two states are at an equal, slightly higher energy sub level. These differences are tiny. Jumping from the 0 to the +/-1 levels requires only a small amount of energy. A microwave photon of 10.4 centimeters will be enough.
Now, these secret energy platforms of NV centers were mapped out by the '90s. But for a long time, no one thought to use them as magnetometers. There was a decade before the light bulb went on for a bunch of us to think about them as sensors. It takes a mindset switch to think differently. And once you do, you realize, "Oh my goodness, this could be useful."
So let's apply a magnetic field to this diamond and see what happens. If we slowly turn up the field strength, you'll see that the +1 and -1 levels are starting to shift. To understand why, we can use a compass needle as an analogy. Naturally, a compass needle will align itself with the magnetic field of the Earth. And this is the lowest energy relaxed state that the needle can be in. And it's analogous to the behavior of the system in the ms = -1 state, which is why its energy level drops slightly. But if ms = 1, the system flips. This would be like taking an external magnet and applying it to this compass needle, flipping it 180 degrees. And then if I'm careful in retracting this magnet, I can actually get the needle to stay in this place. And this is the highest energy this needle can have sitting in this unstable position. Now if I tap it, it will actually go back. It's possible, but it's a higher energy state. So the ms = 1 level slightly rises. And if ms = 0, it doesn't react to the field, which is why this level hasn't changed.
Now, if you keep turning up the magnetic field strength, you'll notice that the levels get further and further apart. This phenomenon is called Zeeman splitting. It's described by a simple formula that gives you a direct link between the energy split and the magnetic field strength. So in the presence of a periodic magnetic field like that generated by the heart, we would theoretically see a rhythmic separation of these lines. And these two energy levels absorb light at two different microwave wavelengths, which change depending on the strength of the field.
So what we can actually measure is which microwave wavelengths the diamond is absorbing. When there's no magnetic field, the levels are fused and produce a single absorption line at the wavelength of 10.4 centimeters. But when there's an external magnetic field, they produce two separate absorption lines. Now, we've simplified it a bit, but by measuring how spaced apart these lines are, you get the field strength. This is how an NV diamond magnetometer works.
Was the diamond magnetometer ever used to detect a heartbeat? So what has been done for sure is, you know, for certain is detection of magnetic fields generated by neurons. Yeah, I mean, which is to some extent connected to the heartbeat question. Neuron activity, to my knowledge, has been first seen in 2015. Okay, well, that's, wow, that's impressive.
So could it pick up a heartbeat from kilometers away? Well, in 2022, researchers were able to pick up the magnetic field of a rat's heart, but it was done using a thoracotomy, which means the rat's chest was open and the diamond was less than two millimeters away from the heart. Okay, but the human heart produces a stronger magnetic field. And the tech, the CIA might have deployed, could be decades ahead of what is publicly known.
You're former CIA operations officer and you've worked in the Middle East, right? So what was your first reaction to this news? Well, the fact that the CIA's involved in leveraging technology is consistent with their mission and their charter. But I defer to smarter people in engineering and science like yourself to figure out the exact technique that might be used. But the processes, of course, are consistent for what we've done.
We can't say for sure whether the CIA has this tech, but we can use physics to estimate how sensitive it would need to be. Well, the strength of a magnetic field falls off with the cube of the distance from the source. So if the magnetic field of the heart when measured at the chest is 50 pico Tesla, or 5 times 10 to the -11 Tesla, well, then just 100 meters away, this falls off by a factor of a billion to 5 times 10 to the -20 Tesla. And at 50 to 100 kilometers, this could drop to as little as 10 to the -30 Tesla.
The most sensitive measurement ever made at the frequencies that the human heartbeat work at is at the 10 to the -15 Tesla level. And that's in a shielded room. So you'd need a system that is 15 orders of magnitude more sensitive than the superconducting quantum interference devices and 18 orders of magnitude more sensitive than diamond NV sensors. 18 orders of magnitude is a lot, sounds quite unfeasible.
It's not like the hills of Iran are devoid of animal life. They also have heartbeats and possibly larger hearts than humans. There's also the magnetic field of the drone or the helicopter the device might be mounted on. And, finally, there's the fact that a magnetic field of 10 to the -30 Tesla is weaker than a magnetic field an electron will give you a meter away.
The New York Post is notoriously a very good place for amusing fiction. On the day before we saw this article, we also saw an article about how they had a technology where it was a beeper, and that was one way that they were able to detect him. And these are things that we know about already. We also know that there may well have been other intelligence methods used, but this isn't really necessary. And then that brings you to the point of like, why would they make this up? I think New York Post is known to print a lot of stuff. I'm not a real fan of the credibility of the press to report things, having seen reality and then seeing what the press reports.
How about deception stories and like false narratives published by not only the CIA, but other agencies? Is this often the case? If you look historically, the idea of fooling your enemy, particularly when you have some vulnerability to protect, goes back thousands of years.
During World War II, German bombers frequently attacked Britain at night. And to retaliate, the British would fly up to intercept and somehow kept finding these bombers in the dark and would attack them. Now, UK officials told the press that the pilots were able to do this because they ate a lot of carrots, which was improving their vision at night. But some experts believe that this was actually a cover story meant to distract the Germans from the fact the British installed radars on their planes. Is that where the idea that carrots give you good eyesight comes from? I think so. I think this is the original, yeah, the original myth. That is crazy. Yeah.
But, okay, there's one thing that still bothers me. If this is likely fake, then why is everyone saying no comment and declining to talk? There must be something here, you know? Well, these NV centers and diamonds are also used for quantum computing. But the more interesting, probably confidential way they could be used is as navigation devices. The Earth's magnetic field creates a unique pattern all across the globe. Then to place an object into this map, and if you know all of these perturbations and inhomogeneities, you can infer where you are without having any GPS reception anymore. With the rise of GPS spoofing and jamming over the last couple of years, that could be incredibly powerful.
So NV magnetometers do exist with these synthetic diamonds, and they do have potential military applications. It's just that detecting heartbeats kilometers away probably isn't one of them.
I wanna give a shout-out to a great Scientific American article on this story by Deni Béchard that initially expressed skepticism in Ghost Murmur as a potential technology. It's a great read and you check it out.
