[belorn]

After watching the video I was a bit surprised to not see them explore the possibility that the word "heartbeat" may not refer to an actually human heart, but rather the concept in similar way that computers and servers uses the term heartbeat. The US military can have a low energy transmitter that sends a heartbeat signal, but which methods of sending/receiving isn't disclosed to the public.

I would look if there is anything close to the idea of an "magnetometry" that could be used for communication with an sender and a receiver. Something like say the idea expressed here https://onlinelibrary.wiley.com/doi/full/10.4218/etrij.2023-...