Note by @fastfinge

@alexisbushnell Okay, I don't have links to hand, but I'm a licensed ham radio opperator, and this is the kind of theory we learn. The danger from a microwave comes if it is failing to keep the actual waves inside. Microwaves are designed with an enclosure that blocks most of the energy from them. However, you might notice that when you run your microwave, your wifi and cell signal degrades. This is because your wifi/cell and a microwave use similar frequencies. But your wifi just uses a millionth or billionth of the power. So when those waves start leaking out of your microwave, they can drown out the wifi completely. The danger comes from just how much energy is leaking. You can stick a wifi antenna directly in your mouth for hours while it transmits, and nothing bad will happen to you. But if it was putting out the same power of a microwave, you would be cooked. In general, the test I use is this: place your cell phone inside the microwave, and close the door. DO NOT! TURN ON THE MICROWAVE OBVIOUSLY! Now, with the door completely closed, try to call your cell phone from another phone. If it rings while inside the microwave, I'd worry a bit. If it doesn't, I wouldn't. This works because your cell tower is transmitting at low power, and is far away from you. So if your phone can talk to the tower from inside the microwave, it means it's probably leaking more energy than you would really like.