I'm curious about challenges (what's bad with AM broadcast in an unmanned tunnel?) and why the formally verified killswitch was necessary?

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meindnoch an hour ago | parent [-]

A tunnel basically acts as a waveguide. A sufficiently shaped AM transmission can turn the tunnel into a cavity resonator, basically a huge microwave oven. There have been multiple cases where people were cooked alive in mines and utility tunnels, due to faulty AM equipment broadcasting at the wrong resonant frequency.

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samschooler 8 minutes ago | parent | next [-]

I did a more aggressive internet search. This seems not possible given physics, as well as not documented (at least in the US) in the CDC Mine Accidents Database [0], which has been recording mine accidents since before the discovery + invention of AM radio.

[0]: https://wwwn.cdc.gov/NIOSH-Mining/MMWC/MineDisasters/Table

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albumen an hour ago | parent | prev | next [-]

Fascinating. Any references? A cursory web search reveals nothing.

	▲	kurthr 4 minutes ago \| parent \| next [-]
		This is basically hilarious. Leaky Feeders are a few watts. and even a high powered multi-kW AM radio with 200m wavelength wouldn't do much in a rough walled tunnel multiple sq meters in cross section. It's both too large for there to be significant power density, and much less than a wavelength in diameter except in length where the tunnel passively attenuates the signal.
	▲	andrewstuart 9 minutes ago \| parent \| prev [-]
		Fascinatingly false.

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CamperBob2 43 minutes ago | parent | prev [-]

That is hilarious. You win the Internet for February 18, 2006.