Introduction:

The microwave oven is one of the most widely used things in America and the World. Microwaves was discovered by accident in 1946 when Dr. Percy LaBaron Spencer was working with a magnetron and noticed that his chocolate bar had melted and it was caused by microwaves, this amazing discovery this lead to the invention of the microwave oven!

One of the first microwaves made for you home
Disocovery:

The discovery of microwaves and later the invention of the microwave oven was all because of a chocolate bar that melted in the pocket of Percy Spencer while he was standing in front of and operation magnetron. When he noticed that his chocolate bar had been melted he instantly made the connection between the magnetron and the chocolate bar. After he made the connection he grabbed some un-popped kernels of corn and turned up the power of the magnetron and put the kernels on the table and watched, as the started to pop this would turn out to be the world’s first batch of popcorn. His first attempt at trying to put this knowledge to use was almost a disaster because it was about five and a half feet weighed over 700 pounds and cost about $5000 and put out 3000 watts of power (5x as powerful as a regular oven today) and this was just too bulky and expensive for anyone to buy at the time. But this massive microwave worked like a charm, if you wanted a nice steak and baked potato dinner you could have your steak in 50 seconds and your potato in 2 minutes. It took 20 years before the company Raytheon realized that you didn’t need such a powerful magnetron to cook your food. This lead to smaller and more compact microwaves and as they got smaller and more advanced the prices went down and more and more people bought them.

-How it works
Unlike a conventional oven that cooks food from the outside in a microwave oven cooks the food from the inside out. The difference between a microwave oven and a conventional oven in that in a conventional oven you heat up the air around the food item which cooks the outside of the item and moves to the middle by conduction this is why there is a crust on the outside and it is moist on the inside of the things that you cook in a conventional oven lie cakes and bread. As apposed to the conventional oven the microwave oven produces microwaves that travel inside the food item and excite the water and fat molecules cooking the item evenly. Because the microwave oven cooks food this way some of the microwaveable pastries come with a sleeve around it, which heats up and crisps the outside of the pastry.
A shetch of how the inside of a microwave by Percy L. Spencer
Biography:

Spencer was born in Howland, Maine. His father died in 1897, and his mother left him a short time later. He lived with his aunt and uncle after that. He never graduated from grammar school, but went to work in a mill as an apprentice at age 12, before joining the U.S. Navy in 1912 to learn wireless telegraphy. He joined the Raytheon Company in the 1920s. He became Senior Vice President and a member of the Senior Board of Directors at Raytheon. He received 150 patents during his career at Raytheon; a building there is named after him. Spencer was married and had three children, James, John, and George.

Impact on the world and humanity:

In 1976, a reported 17% of all homes in Japan were doing their cooking by microwaves, compared with 4% of the homes in the United States the same year. Before long, though, microwave ovens were in the kitchens in over nine million homes, or about 14%, of all the homes in the United States. In 1976, the microwave oven became a more commonly owned kitchen appliance than the dishwasher, reaching nearly 60%, or about 52 million U.S. households. In the United States now almost 95% of kitchens have one microwave and almost 9% have two or more microwave ovens in their house. America's cooking habits were being drastically changed by the time and energy-saving convenience of the microwave oven

Journal Article Summary:

http://www.jada-plus.com/cgi/content/abstract/110/2/194

Fungi, viruses, and aerobic and anaerobic bacteria, including spore formers, can easily be killed in a conventional microwave oven with proper modifications. Only if the items that are beign sterilized are rotated in a 3-dimetional manner when being microwaved.

References:

http://home.howstuffworks.com/microwave2.htm
http://www.smecc.org/microwave_oven.htm
Video:
http://www.youtube.com/watch?v=4h1ESUz2H3E
Pictures:
http://www.smecc.org/microwave_oven.htm