If we ignore 5GHz WiFi, then both microwaves and WiFi create photons at ~2.4GHz but one of them will boil water in a few seconds but the other doesn't have any effect. So what's the difference?
Is it simply the number of photons created? Is that what the wattage of a microwave measures? If so, what would be the wattage of a wireless router?
Does the enclosed space have anything to do with it?
If it all has to do with power output could I put enough WiFi routers together in a room to cook a turkey (from microwaves and not waste heat)?