Key Moments
Can a quantum sensor detect your heartbeat from 60 km away?
VeritasiumKey Moments
The CIA's 'Ghost Murmur' tech, claimed to detect heartbeats from 60km away via quantum sensors in diamonds, is likely fiction due to extreme sensitivity requirements.
Key Insights
The magnetic field of the human heart is incredibly weak, about 50-100 picoteslas, a million times weaker than Earth's magnetic field.
Quantum magnetometers using nitrogen vacancy (NV) centers in synthetic diamonds can detect magnetic fields at room temperature, a significant advance over older SQUID technology.
Researchers have detected magnetic fields from neurons, but detecting a rat's heart required a thoracotomy and the sensor to be less than 2mm away.
Detecting a human heartbeat from 50-100 km would require a sensor 18 orders of magnitude more sensitive than current diamond sensors.
The 'Ghost Murmur' story likely originated from a New York Post article, which is known for sometimes publishing unverified or fictional accounts.
NV magnetometers hold promise for navigation systems that don't rely on GPS, which is becoming increasingly vulnerable to jamming and spoofing.
CIA's 'Ghost Murmur' claim: A tale of extreme sensitivity
The story of the CIA's 'Ghost Murmur' technology, capable of detecting a human heartbeat from kilometers away, emerged from a New York Post article following the rescue of a downed pilot. The article suggested that advances in quantum magnetometry, specifically using defects in synthetic diamonds, enabled this detection. However, the extreme weakness of the heart's magnetic field presents a monumental challenge. While the heart's magnetic field is the strongest in the body at around 50-100 picoteslas, it's still a million times weaker than Earth's magnetic field. Early detection in 1963 required highly controlled, shielded environments. This extraordinary claim necessitates immense sensitivity to pick up such a faint signal amidst numerous other magnetic interferences.
The heart's faint magnetic signature
Electrical impulses in the body generate magnetic fields. The heart, with its coordinated muscular contractions, produces the strongest among these, roughly 50 to 100 picoteslas. This magnetic field was first detected in 1963 under very specific, low-noise laboratory conditions, highlighting its inherent weakness and the difficulty of measurement. Even with advancements like Superconducting Quantum Interference Devices (SQUIDs) in the 1970s, which could detect fields as weak as a few femptoteslas, practical field deployment for such sensitive measurements remained elusive due to the need for controlled environments and susceptibility to interference.
Quantum sensors in diamonds: A promising leap
The potential breakthrough lies in quantum magnetometry, particularly sensors utilizing nitrogen vacancy (NV) centers in synthetic diamonds. Pure diamonds are inert to magnetic fields, but introducing defects—like replacing a carbon atom with nitrogen and creating a neighboring vacancy—creates NV centers. These centers trap electrons with spin, acting like tiny bar magnets. Crucially, these NV centers can be manipulated and read out using light and microwaves. The spin state of these trapped electrons is sensitive to external magnetic fields. When exposed to a magnetic field, the energy levels of these electron spins shift, a phenomenon known as Zeeman splitting. By measuring how these energy levels split, one can infer the strength of the magnetic field, offering a solid-state, room-temperature sensing capability that surpasses older technologies like SQUIDs in certain aspects, though not yet in extreme sensitivity for field operations.
The mechanics of NV center magnetometry
NV centers in diamonds respond to magnetic fields through changes in their electron spin states (MS = 0, +1, -1). These states have distinct energy levels. Applying an external magnetic field causes the +1 and -1 spin states to shift in energy relative to the 0 state, a measurable effect called Zeeman splitting. The degree of splitting is directly proportional to the magnetic field strength. By shining light on the diamond and measuring which microwave wavelengths are absorbed or reflected, scientists can determine these energy level separations and, by extension, the strength of the ambient magnetic field. This forms the basis for diamond-based magnetometers.
The unbridgeable gap in sensitivity for long-range detection
Despite the sophistication of NV diamond sensors, the sensitivity required for detecting a heartbeat from kilometers away remains astronomically high. The magnetic field strength from the heart decreases with the cube of the distance. At 100 meters, it would be a factor of a billion weaker than at the chest. At 50-100 km, the field could drop to 10^-30 Tesla. Current state-of-the-art shielded room measurements for similar frequencies reach about 10^-15 Tesla. This implies a need for a device 18 orders of magnitude more sensitive than current diamond sensors, a requirement deemed highly unfeasible. The presence of other magnetic field sources, such as the Earth's own field, animals, vehicles, and the detection platform itself (e.g., a drone), further complicates any long-range detection attempt.
Skepticism and alternative explanations for the rescue
Given the immense sensitivity gap, the 'Ghost Murmur' story is widely viewed with skepticism by experts. The New York Post's reputation for sensationalism and sometimes fictional reporting is noted. Alternative explanations for the pilot's rescue, such as a sophisticated rescue beacon that was used sparingly or other classified intelligence-gathering methods, are considered more plausible. The lack of corroborating evidence and the classified nature surrounding NV diamond research, leading to NDAs for researchers, also fuels speculation but doesn't validate the extreme claim.
Future applications of NV magnetometers
While detecting heartbeats from afar appears improbable, NV magnetometers hold significant promise for other applications. Notably, their ability to sense magnetic fields with high precision makes them ideal for navigation systems. By mapping the Earth's magnetic field, these sensors could provide accurate location data even in the absence of GPS, which is becoming increasingly vulnerable to jamming and spoofing. This potential for robust, GPS-independent navigation is a key area of ongoing research and development for military and civilian uses.
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Relative Strengths of Magnetic Fields
Data extracted from this episode
| Source | Field Strength (Tesla) | Distance from Source |
|---|---|---|
| Human Heart (measured at chest) | 50 picoteslas (5 x 10^-11) | Chest |
| Human Heart | 5 x 10^-20 | 100 m |
| Human Heart | 10^-30 | 50-100 km |
| Most sensitive measurement (shielded room) | 10^-15 | N/A |
Common Questions
Ghost Murmur is the reported name of a futuristic device allegedly developed by the CIA, capable of detecting a person's heartbeat from kilometers away by sensing the magnetic field it produces.
Topics
Mentioned in this video
The name of a purported futuristic device allegedly used by the CIA to detect heartbeats from kilometers away, which the video investigates as fact or fiction.
Stands for nitrogen vacancy center, a defect in synthetic diamonds that traps unpaired electrons and is key to quantum magnetometry.
The phenomenon where energy levels of an atom's electrons split in the presence of an external magnetic field, described by a formula linking split energy to field strength.
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