|I recently place a green tomato in the microwave oven. I forgot to turn on the microwave and in the morning the tomato was ripe. Can you explain this? — KH
No. When a microwave oven is off, the cooking chamber contains nothing special at all—just some trapped air and perhaps a little light that enters through the window. Even when it is operating, a microwave oven never produces any ionizing (high energy) radiation so there are no long-term effects such as radioactivity present in the cooking chamber when the oven is off. The tomato was simply sitting in a sealed metal box overnight. Since some fruits ripen faster in sealed environments, perhaps that accounts for your observation.