When you shove a Sainsbury’s ready meal into the microwave for  5 minutes after a long day, you do not often consider how on earth one works. The natural assumption would be that it works in a way very similar to an oven, where the entire space is heated up leading to your Chicken and Bacon pasta bake also warming. But if that's the case why is there such a huge difference between the time taken to heat something up in the microwave and to heat something up in the oven. Maybe its due to the size of the area that needs to be heated up, but it only takes about 5 minutes to preheat an oven so that doesn't explain it. Well it is in fact due to the fact they use a completely different mechanism to heat up your food.

As the name implies a microwave makes use of microwaves to warm your ready meals. A microwave is a wave on the electromagnetic spectrum and can transfer energy. The wavelength of microwaves used in microwaves is one that can be absorbed by water in your food, which then subsequently absorbs energy and becomes warmer. And when the water in your food becomes warmer so does your food.

This was discovered when an engineer at Raytheon in 1946 named Perry Spencer was playing around with a magnetron , something that shoots out microwaves, and a snack of his was melted. A year later Raytheon built the "Radarange", the first commercially available microwave oven. It was almost 1.8 metres tall, weighed 340 kilograms and cost about US$5,000 ($56,000 in 2018 dollars) each.

Curiously, Raytheon today is not known as the builder of microwaves (though they used to build some fridges as well) but is perhaps best known as the US military contracting company that built the patriot missile.