I'd poured myself some coffee and forgotten about it, so I nuked it to reheat it and when I opened it up there was a little ant on the outside of the mug crawling around fine as can be. This got me thinking about microwave ovens and how they function and I wanted to see if my guess was right, and I'm still not sure because apparently its a recurring phenomena many have asked about and there are various conflicting answers. However here's a fairly good one, I thought, and educational about microwaves too.

To understand the reason why an ant survives in a microwave oven is to understand the way a microwave oven works. A microwave oven emits a form of energy called ‘standing waves”. That is to say that evenly spaced, stationary waves of energy bombard the turntable (or plate) in a vertical fashion so that only specific areas of the turntable are struck by the waves. Everything inside the microwave is not necessarily exposed to the waves, especially when the turntable is motionless. This is why you notice that certain portions of your food are well heated while others remain cold whenever the turntable is not moving. The sole purpose of the moving turntable is to ensure that all areas of the food pass through the stationary ‘standing waves”. Increasing the intensity of the microwave oven doesn’t turn up the heat, it activates more ‘standing waves” in a given area of space.

The physical size of an object has little to do with its susceptibility to microwave generated heat. In fact, chemists use microwave technology to heat sub-micron particles. The ant’s size only comes into play because he is able to navigate between the ‘standing waves’ by sensing the areas where there is high volume heat and low volume heat. You can visualize the patterns of low heat v. high heat by filling a paper plate with marshmallows and putting them in the oven with the turntable turned off. After a few seconds you will see a pattern of melt or blistering on the marshmallows that are exposed while the others seem unaffected. Additionally, the intensity of the waves is greater in some areas than in others. You can see this by putting a pat of butter on the surface of the turntable and another on the bottom of an overturned paper cup. The one on the cup will melt long before the one on the turntable, because the wave intensity is lower near the bottom and sides of the oven than it is at various points elevated just above the turntable (where food heaped on a is plate usually located).

A single ant, or even a few ants, can simply walk around between the waves of energy, making their way from one safe area to the next, and avoid getting nuked. If, on the other hand, you put a thousand ants in your microwave and agitate them so that they are running around in a panic, you will, without a doubt, see many of them turned to toast.