Yep. Water molecules resonate at 2.4 GHz (so that's what microwaves emit), which is also the unlicensed radio spectrum that bluetooth and a lot of other consumer radio devices operate on.

Not sure which is the chicken and which is the egg here.

But the observatory had either a well-shielded microwave or break room was in an adjacent building or something (they did consider "ya know, microwaves make RF emissions, and we're running a sensitive RF measurement facility here"). It was just when the door was opened that the energy emissions exceeded the design specifications. Classic human factors always find a way around your design.

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ianburrell 6 days ago | parent [-]

The microwave came first. The 2.4GHz ISM band was reserved because of microwave interference. It turned out to be perfect for short-range low-power radio because microwaves don't run all the time, and don't go far outside the house.

Microwaves have gotten better shielding. My old one used to take out Wifi and Bluetooth standing next to it, but my current one doesn't cause problems.

	▲	paulgerhardt 6 days ago \| parent [-]
		Well it was radar. The first Raytheon microwaves were really pushing for 3GHz not 2.4GHz. If you like to play Connections, the reason for that is the first mass produced magnetrons were made by gun manufacturers like Colt and Smith & Wesson and the tooling for gun bore holes and magnetron cavities lined up at 3GHz. The official FCC minutes from 1945 [1] indicate that publicly they were marketed for heat therapy massages not food, with a weird wink, wink that if they could get a carve out for using for medical reasons they could also sell it to the Navy for reheating food as well. The ISM carve out came after by a couple of years in 1947 because Raytheon had got an exception for this machine, not the other way around. The whole origin story of why this particular slot of spectrum is full of carts before horses. That water oscillation thing is a common misconception - water oscillates at much higher frequencies [2]. [1] https://www.worldradiohistory.com/Archive-FCC/FCC-Annual-Rep... [2] https://www.sciencedirect.com/science/article/abs/pii/S01691...