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.
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.
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...
Press `STOP` first, got it.
> The U.S. Environmental Protection Agency says most granite countertops are safe, adding little to a house's radon level. It depends on the rock that is used, the agency says, recommending that homeowners concerned about radon get their countertops tested."
https://www.naturalstoneinstitute.org/designprofessionals/ra...
I live in a high-radon part of the world (Appalachia), and there are so many more benefits to having an ERV[0] than just getting rid of toxic gasses (handles farts, too!). Worth every penny — one will remove stink from the entire 1000sqft house (including indoor cat litterbox), with partial heat/humidity recovery.
[0] Energy recovery vent, e.g. https://www.homedepot.com/p/Panasonic-WhisperComfort-60-20-5...
They finally traced it to people using the microwave in the break room in a very specific way. Some people liked to open the microwave door before the timer went off. The microwave stopped, of course, but there was a split second where it was still emitting while the protective cage was opened, and the energy that leaked out during those couple of ms were enough to screw with the observatory equipment.
Aliens? Nope, just some tired grad student reheating their coffee.