[galdosdi]

Because microwaves don't heat matter. They heat* H2O molecules. This one weird fact is responsible for all of the weird differences between how they cook and how other more classic cooking methods work.

We're taught that heating has three styles: convection, conduction, radiation. But AFAIK, microwaving is a fourth and distinct style.

*: Even more specifically, they add rotational momentum to these molecules, which is not the same as heat, but gradually turns into heat (which is translational momentum) as they knock around. This, in addition to the fact that only the water is being heated, and that the microwave waves touch the food in an uneven pattern even if mitigated by a rotating platter, is why stirring or waiting or using "low power" (dithered) is an important part of microwave recipes, as well as why high moisture foods or intentional steaming works so much better in it

[firesteelrain]

Microwaves also affect other polar molecules and ions in food, not just water.

This excitation leads to the generation of heat, which is then transferred through the food via conduction.

Microwaving is indeed considered a form of dielectric heating, which is a subtype of radiation. It’s distinct from conduction, convection, and traditional infrared radiation but still falls under the broader category of electromagnetic radiation-based heating.

[bsder]

> Microwaves also affect other polar molecules and ions in food, not just water.

So why does sugar seem to heat so preferentially?

I always found that microwaving any dish with a "syrup" made it the temperature of hot lava while the rest of the dish was still cold.

[firesteelrain]

Microwaves seem to prefer syrupy foods because syrup typically has a high sugar and water content. Both sugar and water molecules are efficient at absorbing microwave energy, so they heat up quickly. This is why syrupy parts of a dish often get much hotter than other parts when microwaved.

[djmips]

Is that you GPT?

[firesteelrain]

Huh?

[numpad0]

Isn't that because sugar syrups don't boil and get temperature capped at 100C?

[sadhorse]

Microwave heating is not a fourth form of heat transfer as it name implies: microwave radiation. Yes, the heat is not being radiated by a thermal source of microwaves, but it is radiation being absorbed. Hence radiation is the mechanism.

Rotational momentum is also heat as it is kinect energy related to movement, linear or not.

[galdosdi]

I'm speaking from a practical cooking perspective, not a technical physics perspective. The radiation from flames or the sun affects food very differently than microwaves do.

For the same reason, I probably messed up other physics technicalities. It would have been nice if I added a caveat I guess, but so it goes. My mental model may be simpler than the truth, but it's a lot better for achieving practical results in the kitchen than nothing than "microwaves heat stuff up fast", which is what I had before and is a really shit model that fails to explain most of their odd behavior.

[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.