Student science experiment finds plants won't grow near Wi-Fi router

[William Seger]

146. There is no known way that microwaves can cause cancer

All things that are known to cause cancer (i.e. certain chemicals, certain viruses, and certain radiation) do so by damaging DNA. X-rays can cause cancer because they can damage DNA by knocking electrons out of molecules, allowing the atoms to recombine as different molecules. But that "photoelectric" effect requires electromagnetic photons with a certain minimum amount of energy, which was the subject of one of Einstein's famous 1905 papers that laid the foundation of quantum mechanics. Ultraviolet light photons have that minimum necessary energy, which is why sunlight can also cause cancer and why "sunblocker" actually blocks ultraviolet. Photons with less energy than ultraviolet light (i.e. visible light on down through infrared, microwaves and radio waves) are called non-ionizing radiation because they do not have enough energy to ionize a molecule by knocking out an electron. It isn't a cumulative effect: A single photon with the required energy can cause an atom to emit an electron, but no number of photons with less energy can do so.

The reason that most scientists do not believe that microwaves can cause cancer is because ultraviolet photons have about 600,000 to 1,000,000 times more energy than microwave photons.

The only know effect that microwaves have on humans is that it heats water molecules, but heating from a cell phone would be immeasurably slight and completely swamped by other sources of heat.