Ghost Murmur and the Heartbeat: Can the CIA Really Track Your Heart Rate from Miles Away?

Overview

Veritasium examines a sensational claim that the CIA used a device nicknamed Ghost Murmur to detect a rescuer’s heartbeat from kilometers away, evaluating the physics of heart-generated magnetic fields and the feasibility of NV-diamond magnetometers.

Key insights

• The heart’s magnetic field is extremely weak, on the order of 50–100 picoteslas, making distant detection challenging amid background noise.
• Diamonds with nitrogen vacancy (NV) centers can function as room-temperature magnetometers by reading spin-state changes via light, but face practical limits in the field.
• Public reporting of such tech is contested, with skepticism about verified sources and NDAs surrounding researchers.
• NV magnetometers have real potential for navigation without GPS, but detecting a heartbeat kilometers away remains speculative.

Overview and the Core Claim

In this video, Veritasium dissects a New York Post report claiming that the CIA employed a futuristic device, Ghost Murmur, to locate a downed officer by sensing the magnetic field of his heartbeat from kilometers away. He emphasizes the need to separate sensational headlines from physics-based possibilities, noting the human heart’s field is incredibly faint and that any solution would have to distinguish it from background signals, vehicles, and animals in a desert environment. The discussion frames the central question: could a magnetic heart signal be detected at long range in real-world conditions, or is the claim closer to science fiction?

“Ghost Murmur.” - Veritasium

The Heart’s Magnetic Field: What We Know

The heart generates magnetic fields because it uses electrical impulses to coordinate its pumping action. The magnetic field strength at the chest is typically cited around 50–100 picoteslas, which is billions of times weaker than Earth’s own field. Early measurements required highly controlled environments with long integration times, far from the dynamic noise of moving aircraft and desert radio signals. Veritasium walks through why such weak signals are easy to obscure and why field measurements demand isolation from motion and interference. The video also compares historical detection capabilities, such as 1963 heart-field measurements and later SQUID-based magnetometers, which still face significant practical constraints for real-world, in-field use.

“The heart muscles fire in a coordinated way, the magnetic field they produce is around 50 to 100 picoteslas.” - Veritasium

NV Centers in Diamonds: From Energy Levels to Magnetic Sensing

The core physics rests on diamonds that contain nitrogen vacancy (NV) centers. These defects trap two unpaired electrons whose spins form a mini two- or three-level system (Ms = 0, ±1). When exposed to magnetic fields, the energy levels split (Zeeman effect), shifting microwave transition frequencies. By shining light and monitoring the absorption of microwaves, one can infer the magnetic field. Veritasium explains how NV centers turn a solid into a practical magnetometer, with room-temperature operation and solid-state robustness, in contrast to older, more fragile magnetic sensors. The discussion clarifies how optical readout translates spin state into a measurable signal, enabling magnetometry outside shielded labs, at least in principle.

“These NV centers become particularly useful when they trap two unpaired electrons.” - Veritasium

Is Heartbeat Detection from Kilometers Away Feasible?

Veritasium surveys public skepticism about the claim by evaluating signal strength decay with distance, which follows an approximate inverse-cubed dependence for magnetic fields. He discusses the necessary sensitivity to detect 10^(-15) tesla–level signals in free space and the gap to reach 10^(-30) tesla distances that would be required for kilometer-scale detection in a desert. The video compares publicly known measurements (neuronal magnetic fields, rat heart signals at very close range) with the speculative leaps needed for a heartbeat to be read kilometers away. He also emphasizes that the New York Post article is an unverified source, urging caution about sensational tech reporting.

“The strength of a magnetic field falls off with the cube of the distance from the source.” - Veritasium

Practical Considerations and Real-World Applications

Beyond the heartbeat question, the NV-diamond magnetometer has a plausible role in navigation without GPS using the Earth’s magnetic field and known inhomogeneities. Veritasium discusses alternatives and limitations, including background noise from animals, vehicles, and the environment, as well as issues of NDAs and transparency in research. He also touches on quantum sensing’s broader potential, noting that diamond NV sensors remain a topic of active research and that strong claims about battlefield-scale heart detection are likely overstated given current physics and engineering constraints.

“Earth’s magnetic field creates a unique pattern all across the globe.” - Veritasium

Conclusion: What It All Means

In closing, the video acknowledges NV-diamond magnetometers are real, with legitimate military applications like navigation and field sensing, but the specific claim of tracking a heartbeat from kilometers away is, at best, speculative and unproven in public sources. Veritasium cites Scientific American coverage and argues that the science supports cautious optimism about magnetometry in general, while remaining skeptical about extraordinary claims lacking independent verification.

“18 orders of magnitude is a lot, and that seems unfeasible.” - Veritasium