The Sun Sentinel states that microwaves come from several sources, such as speed camera devices, microwave ovens and outer space. Cell phones also generate microwaves with a transmitter chip.
Speed camera devices, usually stationed on roadways, send out microwave pulses that hit an object and then echo back to the device. The length of time it takes for the echo to return to the device shows how far away the object was and how fast it was traveling.
In medicine, microwaves are known for their treatment of cancer. Manufacturing plants use microwaves to generate heat to seal the lids of certain products. Microwaves are even found in homes across the globe. Microwave ovens use microwaves to heat food quickly.
Microwaves also come from the cosmos. The Sun Sentinel explains that in 1965, scientists detected microwaves coming from outer space. This confirmed the Big Bang Theory for many, because within that theory, when the universe was created all matter was extremely hot and cooled over time. As of July 2014, the temperature of the matter allows it to radiate microwaves out into space.
The MIT Technology Review studies the effects of cell phone microwaves on human health. Some researchers have found that the long neurons present in the human body are ideal attractors of microwave photons emitted by cell phones. These microwave photons are believed to cause side effects such as insomnia and headache.