Quarta-feira, 14 de Março de 2012
EINSTEIN E OS TELEMÓVEIS
O físico Robert Park, na sua coluna "What's New" continua a lembrar o que Einstein nos revelou sobre a luz (efeito fotoeléctrico) e o que isso implica para desmitificar muitos boatos que correm sobre as microondas dos telemóveis:
"1. SMART METERS: AND IGNORANT JOURNALISTS.
Several years ago, I signed up for "Google Alerts" about the purported link between "cell-phone radiation and cancer." It's a great service. I get hundreds of Alerts about cell phones, almost all of which are dead wrong.
That's fine; what I'm trying to figure out is why reporters so consistently get it wrong. I tried doing an additional search for "Einstein." It was, after all, Einstein's Nobel Prize winning 1905 paper on the Photoelectric Effect that introduced the concept of wave/particle duality. Einstein described electromagnetic radiation as discrete packets of energy (now called "photons") equal to the wave frequency times Planck's constant.
Photoemission is thus possible only for photons of energy greater than the ionization threshold (about 5 eV for metals). That's in the ultraviolet region of the radiation spectrum, starting at the blue limit of the visible spectrum. Ultraviolet radiation can create mutant strands of DNA that are the seeds of skin cancer. That's why you should avoid tanning salons. You should also avoid sticking your head in microwave ovens with the interlock disabled. Microwave photons from cell phones, microwave ovens, smart meters, and Wi-Fi all have energies about a million times too low to create mutant strands of DNA. Better you should worry about the impending solar maximum. Microwaves can cook your goose, but you will die cancer free.
2. BAD CONNECTION: THE ENVIRONMENTAL HEALTH TRUST.
The most recent book warning about cell-phone hazards is "Disconnect," Devra Davis (2010, Dutton). Does Disconnect mention Einstein? Well," it quotes him at the start of chapter 11, "The right to search for truth implies also a duty." That's it. It makes no mention of his work, but last week something called "The Environmental Health Trust" issued a press release urging the United States to require health warning labels on cell phones. The President of the Environmental Health Trust is Devra Davis. The press release called for donations to support its work."
Robert Park