## SCIENCE-FOR-THE-PEOPLE@LIST.UVM.EDU

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Tue, 31 May 2011 14:18:57 -0400

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 ```Will some physical scientist help me clarify the question of whether microwave radiation COULD cause cancer? Robert L. Park, to whom I am grateful for much enlightenment on many matters, tirelessly reiterates that the only known way for electromagnetic radiation to cause cancer is by breaking a bond in DNA, and this requires a photon of much higher frequency than microwaves have. This seems to me to be relevant but incomplete, for reasons I will give, but Park didn't reply to my query on the point (probably misidentifying me as a microwave-alarmist), so I'm looking for help from others.   What we must talk about is a high-amplitude wave at a frequency too low to break organic bonds, by a factor of a few million. Right? Park says it doesn't matter how high the amplitude is: strengthening the microwave signal is (in his metaphor) just increasing the number of rocks you try to throw across the Potomac, this doesn't get any of them across the river because EACH ROCK has too low an energy. I object that this isn't the whole story, because a periodic wave is not exactly sinusoidal, the sine wave at its fundamental frequency comes accompanied by harmonics at multiples thereof. In quantum terms, that means that the electromagnetic signal consists of photons at the energy belonging to the fundamental frequency, accompanied by a cloud of photons at multiples of that energy. Now (as I have explained to many undergraduate classes) the higher the harmonic the lower the amplitude: for the n-th harmonic, the amplitude goes down like 1/n, meaning that the power goes down like 1/n^2. By the time n is around a million, this factor is around a trillion. But not zero. (True, a very smooth wave has weaker higher harmonics.) In order to be sure a very very strong microwave signal could not break a chemical bond, I would have to know quantitatively HOW strong.   Maybe somebody here will tell me the numbers on this, I haven't looked them up. It seems evident even without having the numbers that putting a mobile phone to my ear will not endanger me. Thus I am as mystified as Park by the new, more credible study pointing to some correlation with cancer. But it also seems to me that further discussion of the matter ought to include the little wrinkle of HIGHER HARMONICS.   Chandler ```