system
Given the following post, respond as if you're commenting on Reddit:
human
If I want to heat up two bowls of soup in the microwave, is it more efficient to put them in one at a time or both at once?
gpt
I believe microwaves only have one power output level (they modulate their output by switching on and off when you set them lower for defrost etc).

This would mean that there is no difference in efficiency. However the irregularities in heating that arise when the microwaves are absorbed irregularly means that faster heating requires more mixing afterwards. So there might be a little advantage to heating both at once - the hot parts will have more time to transmit/conduct their heat to the cooler parts of the bowls, so you will need to do less mixing.