So, thats how back in 1945 Spencer unwittingly discovered that his radar could cook him and his popcorn as well ;-). Anywayz, over half a century on, we're literally swimming in a sea of microwave signals. TV towers, telecom repeaters, cellular networks ... and 802.11 - the relatively humble WiFi.
Cooking food with microwaves was discovered by Percy Spencer while building magnetrons for radar sets at Raytheon. He was working on an active radar set when he noticed a strange sensation, and saw that a peanut chocolate bar he had in his pocket started to melt. Although he was not the first to notice this phenomenon, as the holder of 120 patents, Spencer was no stranger to discovery and experiment, and realized what was happening. The radar had melted his candy bar with microwaves. The first food to be deliberately cooked with microwaves was popcorn, and the second was an egg, which exploded in the face of one of the experimenters.
What prompted my short study and this post was a recent BBC report WiFi: Why Worry?
lots of blog noise and the fact that I have a WiFi router in my house.
I've bulletted the 'givens' as follows:
1. Natural Electromagnetic radiation exists around us, the most obvious being sunlight (visible and otherwise).
2. There have been studies on the thermal as well as non-thermal effects of EM. The relative biological 'danger' depends on (a) The frequency (b) The power (c) Duration of exposure and an implied (d) Distance from source.
3. Following are some stats I could collect:
a. WiFi normally operates at around 2.4 GHz, 100 mW peak power? typically at 50 ft range.
b. A cellphone operates 800 MHz to 1900 Mhz with upto 2W peak and .25W average at typically 0 ft range!
c. A cellphone tower operates at a similar frequency range, power 20 to 30 W continuous at 100 ft plus range.
d. Microwave ovens emit around 1000W peak though human exposure due to typical leaks out of the box are less than .1 W.
On one hand there are many a scare sites that say - "look, if this stuff can 'pop' corn and break down DNA structure of bio materials inside a petri dish - it can fry you too! So cover yourself with anti-EMF paint and wear a Aluminium Foil Deflector Helmet"
Here's a seriously fun study that some MIT dudes conducted with the AFDH.
At the other extreme are many 'studies' (some say - industry sponsored) as well which conclude that normal human exposure to these is 'fine' since they haven't literally found anyone 'directly' fried or even made cancerous directly through WiFi or cellphone! - at least statistically.
So, where does that leave us? The usual middle ground for now - avoid em as much as possible - for instance - by not gluing the cellphone next to ones ears for over a few mins, not fixing the WiFi router under the office chair (does someone do that?) and not drying a cat inside the microwave oven! ;-)