I saw an article recently which frustrated and annoyed me. In short, the article is a World Health Organization discussion of various studies done to measure the medical effects of cell phone radiation. Some of the studies indicated that cancer rates were higher for cell phone users, and so the WHO was issuing a warning that it could be an issue, saying "be careful of cell phone use or you'll get cancer."
Let me point out that, from a Physicists' point of view, this is ridiculous. No, I'm not talking, "Oh, this is surprising." No, it's worse than that: the idea is laughable. It would take extremely decisive results and well controlled studies for this to have any credibility with me. However, studies are split, at the very worst (you can find a list on Wikipedia, with the vast majority concluding that there are no carcinogenic effects).
But why do I find reports of this incredible? The answer goes back to the basic Physics. In 1901, Max Planck proposed the first component of quantum theory: that light comes in discreet packets, his idea eventually evolving to the modern photon. The idea was cited by Einstein in his explanation of the photoelectric effect in 1905, and has been extensively confirmed since (for crying out loud, it's a key concept in high harmonic generation, which was the main thing my lab at BYU worked on). So it's pretty well established: light is absorbed in packets, and the energy of each packet is proportional to the frequency of the light. Now, the effect that light can have on matter is purely an issue of the absorption of these packets, and all they really do is impart energy, momentum, and angular momentum to matter... that's it.
Now, what causes cancer? There's a lot of things, but one thing is common to all cancers: it requires some sort of chemical, electronic, or structural change to a macromolecule in the cell. That is it. Now, light can cause changes of this sort. In fact, that's how we can see: light with sufficient energy causes pigments in the eye to change, which then acts as a chemical and electronic signal which can be interpreted by the brain. However, a change to the molecule like this requires a certain amount of energy.
Okay, now let's bring it all together. We've got cell phone radiation (which is all electromagnetic radiation, i.e., light), which is at a frequency of around 1 GHz. Visible light, which is near the lower end of light that has enough energy to have these kinds of effects is at a frequency of... wait for it... 500 THz, 500,000 times as energetic as cell phone radiation. What does that mean? Simple: It takes about 500,000 photons of cell phone radiation to equal one visible photon, meaning that you would need about a million cell phone photons hitting the same molecule at the exact same time in order to cause damage. Just so you know, that doesn't happen. The probability of getting two photons to hit the same molecule at the same time is practically zero unless the intensity is unimaginably huge (for cell phone radiation we're talking about a trillion times the intensity of light hitting the earth's surface here).
So what does cell phone radiation do when it gets absorbed? Well, it has enough energy to do one of two things: it might be able to make a molecule spin. Or, more likely, it just gives it a little push, making it move. That's it. Cell phone radiation makes the molecules in your head jiggle a little bit. How much is a little bit? Well, we're talking about a power equal to about 3% of what your body emits in radiation (oh, yeah, I forgot to mention, everything at room temperature is emitting radiation, too... and not just that, but radiation that's close to 100,000 times more energetic than cell phone radiation, so without even talking about the fundamental physics of what light does to molecules we could just do the comparison of "You're standing in a room where you're being bombarded by radiation. If that can't cause cancer, neither can cell phone radiation."). And of course that's not the whole story... there's all the other energy that's going around in your body. So, in conclusion, cell phone radiation heats your head by less than the amount that standing in a hot room does. And it doesn't have the physical ability to do anything else to you.
In conclusion, don't worry about cell phone radiation. It's harmless.
Title: Einstein
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