Q: Before wires and electricity, all real-time communication across distances was wireless, such as signaling by bonfires, smoke signals, semaphores. So how did we get from wireless to wired and back again to wireless today?
A: Wired pioneer Samuel
Mo rse developed telegraphy in 1837, and by the time Alexander Graham Bell invented the telephone in 1876, "wires had already crossed the American continent and the Atlantic Ocean," says Robert Lucky in "IEEE Spectrum" magazine. Twenty years later came Guglielmo Marconi's "wireless" radio, used initially in ship-to-ship and ship-to-shore transmission and that played a critical role in the rescue of the Titanic survivors in 1912. But the real "killer app" for wireless turned out to be commercial broadcasts of radio and TV, though virtually all interpersonal communications remained wired (telephone).
Then, with the rise of the cable industry toward the end of the 20th century, "even television transmissions moved from air to earth." Yet today our phones, our "smart appliances," even our computer mice are wireless. This revolution is also sweeping the Third World, where wired infrastructure is cost-prohibitive. As Lucky concludes, "The curious thing is that in the last century, broadcast was all wireless and personal communication all wired; now it is exactly the reverse--but stay tuned.
Q: Why do three-dimensional TVs sometimes seem unsettling, even causing headaches in some viewers?
A: First some background: The concept of 3D dates back to physicist Charles Wheatstone's "stereoscope" of the 1830s, where one image is presented to the right eye and the other to the left eye, explains Byoungho Lee in Physics Today. Then the brain wraps this "binocular disparity" into a single image that gives the illusion of depth, like the popular View-Master of some years ago. Despite technological sophistication, today's 3D TVs still rely on Wheatstone's concept. But unfortunately for viewers, the brain also makes use of the angles the eyes have to rotate to bring an object into central view; and the degree the lenses have to change shape for focusing. Since the flat TV screen is at a fixed distance from the eyes, these special adjustments are lacking, so the brain gets contradictory information. With prolonged viewing, Lee concludes, this can lead to disorientation, discomfort and even headaches.
Q:You might not be quite ready "to befriend a shark," as "Mental Floss" magazine puts it, but what are some good reasons to reconsider your view of the creatures?
A: Even if the movie "Jaws" runs in your nightmares, you're a lot less appetizing to sharks than you think, according to the magazine. The number of U.S. fatalities from sharks from 1990-2006 was 11 (compared with 16 U.S. fatalities from collapsing sand holes), with the chances of dying in a shark attack about 1 in 3,750,000, or about 1/10th that of dying in a fireworks accident. Actually, in the year 2012, there were 80 totally unprovoked shark attacks around the world, compared to an estimated 30,000,000 sharks killed each year by people!
Even if a shark decides to chomp you, you can fight back, the magazine continues.
"Forget that old saw about punching it in the nose. The International Shark Attack File recommends borrowing a page from a pro-wrestling villain and gouging its eyes or clawing at its gills, which are more sensitive than its nose." Or you could try befriending some dolphins, which have been known on at least two occasions to come to the aid of swimmers by forming defensive rings around these would-be shark victims.
"Just like in your favorite documentary,'Flipper!' "
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