As stated in the wikipedia article, the microwaves penetrate to a depth of about 1cm (give or take, depending on the food). So, in a sense, it can be argued that the microwaves heat from inside, though in reality, not very far inside.

The trouble is that microwaves work mostly by heating liquid water. Ice is not liquid water and absorbs microwaves relatively poorly. The already melted parts tend to heat up faster while the still frozen parts heat up very little. This, in addition to the limited penetration, is how you wind up with food that is napalm hot on the outside and still frozen in the middle. If you are trying to defrost something or cook it from frozen, you are much better off using a lower power setting. The peak power output is actually the same, but it gets turned on and off (you can hear it cycling) so that the warm areas of the food have more time to transfer some of that heat to the still cold areas through good old fashioned conduction. Incidentally, this is the same reason that the instructions for many pre-made items tell you to let them sit for 1 or 2 minutes before taking it out of the microwave.

(Some?) Panasonic microwaves claim to be able to lower microwave power linearly without the on/off power cycling. I'm mildly curious if their marketing claims of superior cooking hold up.

http://www.panasonic.com/in/consumer/home-appliances-learn/t...

Indeed, and they seem to make a difference: http://thesweethome.com/reviews/best-microwave/

Wait a second. The Wikipedia page first says that microwave do not cook from the inside out because the microwaves do not penetrate beyond 1 cm. but then it says that microwaves really cook by oscillating the magnetic field which jostles around dipoles like the water in food.

So does the magnetic field only penetrate very close to the skin, or are all the water molecules inside the food being excited, resulting in the food being cooked indeed from the inside?

? Cut a thick piece of meat that's been microwaved. You see complex red/brown variation, because microwaves penetrate. Its not all cooked from the inside, but its different from a conventional heat oven in that there's some cooking from the inside.

Its easy to write sophomoric puff pieces about how we had it all wrong. Just assume an Aristotelian posture of black/white 'facts' and show its actually grey. Voila!

On the other hand you really can get severe burns from the filling of a microwaved jelly donut even if the dough part is cool enough to hold. It's true the microwaves don't heat "from the inside out", but it's also true microwaves heat some materials dramatically better than others.