[HPsquared]

I suppose there's nothing stopping other forms of radiation like the visible spectrum. How about intense blue light? Could it penetrate better than microwaves?

[throwaway342kk]

https://news.ycombinator.com/item?id=29042728

[datameta]

Due to the higher frequency it wouldn't penetrate as well. But it is fun to think about the other EM sources used for cooking.