Einstein & Cell Phones
From Bob Park's "What's New", a pedantic opportunity for me. First: cell phones & brain cancer (cue ominous music):
BRAIN CANCER: OF COURSE CELL PHONES ARE DANGEROUS!
Cell phones may lead to neural atrophy as mindless chatter is substituted for coherent information, but they don't cause brain cancer. This week, however, a doctoral thesis at a university in Sweden suggested that cell phones are linked to some brain cancers. It went around the world in Science Daily on Wednesday. This imaginary link is "discovered" about every five years or so. Photons induce cancer by the photoelectric effect, breaking chemical bonds and creating mutant strands of DNA.In 2001, I was invited to write an editorial on cell phone hazards for the Journal of the National Cancer Institute (JNCI, Vol. 93, Feb 7, 2001, p. 166). I pointed out that the photoelectric effect would require photon energies at the extreme blue end of the visible spectrum, which is why it's the ultraviolet rays in sunlight that cause skin cancer. Microwave photons are about 10,000 times less energetic.
In a classic 2001 op-ed, LBL physicist Robert Cahn observed that Albert Einstein discovered in 1905 that microwaves couldn't cause cancer. The cell phone scare was launched in 1993 on the Larry King Live Show, which is not peer reviewed. It almost strangled the infant cell-phone industry in its crib, but researchers found nothing.
[Robert L. Park, "What's New", 13 November 2009.]
My bold, of course. The first time I read this I didn't even think that it might sound a bit unbelievable to credit Einstein with the discovery that cell-phone RF cannot cause cancer, but that's because I knew what he was referring to: the "photoelectric effect".
In that remarkable year 1905, Einstein published papers on three topics: special relativity, Brownian motion, and the photoelectric effect. When Einstein was awarded the Nobel Prize in Physics for 1921 (which he received in 1922; see here), the citation read:
"for his services to Theoretical Physics, and especially for his discovery of the law of the photoelectric effect" [source]
It had been known for some time that when ultraviolet light fell on certain metals, an electrical current was produced, i.e., electrons were energized enough to be ejected from the metal atoms. There was, however, a profound mystery involved. It was obvious that it was the energy of the light falling on the metal that produced the effect, but for any effect to be seen the energy of the light had to be above a certain threshold. This defied expectations that lower-energy light should produce the effect provided the light was intense enough.
Einstein's answer to the quandary was to use the idea that light traveled in discrete bundles of energy (photons), where the energy of each individual photon depended on the wavelength of the light (shorter wavelength = more energetic photons; ultraviolet photons are more energetic than infra-red photons).
To produce an electron through the photoelectric effect, individual photons must each have enough energy to kick the electron out of the atom. If individual photons have less than the ionization energy then no photo-electrons are produced regardless of the intensity of light (i.e., the number of photons falling on the metal).
The key phrase going through Park's head when he wrote the bit above, then, was something like "microwave radiation is non-ionizing", meaning that individual photons in the radio-frequency stream to and from cell phones have less energy than it takes to ionize (kick an electron out of) atoms in DNA molecules. In other words,
Radiowave energy at the power level used by most cell phones, is not ionizing, and our understanding of cancer is that, in general, ionizing radiation is what is required for radiation to cause or contribute to cancer. [source, with more lengthy discussion]
No matter the intensity of the radiation coming out of the cell phone, no matter its proximity to your brain, the individual photons are not energetic enough to ionize atoms in your body. In fact, the photons' energy is about a million times smaller than it must be to cause ionization.
This is the situation in the heads of scientists who so readily poo-poo the notion that cell phone radiation (oooh, radiation!) is cooking your brain (not true) and causing cancerous tumors. There's no chance of ionization going on, ionization is thought to be a necessary factor in radiation-induced cancers, so there's no plausible mechanism.
Happily, I was able to locate that editorial by Robert Cahn mentioned by Park: "Einstein, Your Cell Phone and You", San Francisco Chronicle, 3o August 2000. Even more happily, it's brief, easy to read, and explains the whole thing much better than I did.
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on Thursday, 19 November 2009 at 00.43
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I'm obviously not a distinguished expert in this. Nor am I a heavy and enthusiastic cell phone user. I do maintain a reasonable, somewhat skeptical curiosity.
One question that comes to mind concerns timing and circumstance. A recent New York Times article pointed out how cancers occur with alarming frequency in humans, but most of the time they're taken care of by the body's own defenses: antibodies. Could it be that for some subtle, as yet not understood reason, exposure to micowave energy just at the time antibodies set upon a neoplasm inhibits the antibodies' ability to stop neoplastic growth? Could the walls/coatings of either cell type undergo an unhelpful change because of microwave energy?
That's just one question. There are surely others. Then answer, I think, will first be arrived at through statistical data on cell phone users over time. But laboratory studies seem to be in order at some point.
So in a larger sense, what I'm asking is, do we know with perfect certainty that only ionizing radiation plays a role in cancer? I'm not so sure.
on Saturday, 9 July 2011 at 12.56
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Okay people:
for electromagnetic radiation, wavelength (think of it as the size of the wave in this case) is inversely proportional to frequency (which is directly related to energy). So electromagnetic waves with a low frequency have a large wavelength (i.e, width) and vice versa. This is why your microwave has a grating in front of it. Visible light has a high enough frequency (and so a low enough wavelength) to pass through the holes, allowing you to see your food. However, microwaves have such a low frequency (and high wavelength) that they actually CAN'T FIT through the holes. your mother is trying to be helpful when she says "don't stand in front of the microwave!" But unless the screen is broken, the microwaves can't reach you. Even if they could, because they're non-ionizing, they could only (surprise surprise) heat things. still no cancer, and microwaves are at a higher frequency than radio waves. If microwaves can't penetrate those holes, then radio waves (an even lower frequency) can't either. If they can't get through holes of that size, what makes you think they can get through your skin? Answer: they can't. If you can't see through your skin, then you can guarantee that electromagnetic radiation of a frequency lower than that of visible light (i.e infrared, microwave and radio) can't either. It can't screw with your immune system because it can't get in your body. It's a physical impossibility spread by a huge misunderstanding of what radiation actually is. The absolute ONLY thing that non-ionizing radiation can do to you is heat your skin. And with radio waves, they carry such little energy that you don't notice the heating effect at all. It's too small. If heating the skin could cause cancer, you'd be killed by your stove long before you'd have to worry about cellphones.