Microwaves Heat from Outside-In, Not Inside-Out

A common misconception is that microwaves heat food from the inside out, but this is false. Microwave radiation (2.45 GHz) only penetrates about 1-2 centimeters into most foods before being absorbed by water molecules. The heat then spreads to the interior through normal thermal conduction, just like conventional heating. This is why thick foods often have hot edges and cold centers when microwaved - the outer layer absorbs the microwave energy and heats up, while the center must be heated by conduction from the outside layers. The myth probably arose because microwaves can heat food much faster than conventional ovens, making it seem like the heating happens throughout the food simultaneously. Understanding this principle explains why stirring food halfway through heating helps ensure even temperature distribution.