童话中的科学

童话中的科学

Kids of any age love to read fairy tales because the storyline never limits the possibility that anything could happen. Curses, spells, and handsome princes reign in worlds beyond the reader’s imagination. But are the most magical moments from some of our favorite stories actually possible? Basic physical principles and recent scientific research suggest that what readers might mistake for fantasies and exaggeration could be rooted in reality. So suspend your imagination for a moment, and look at the following fairy tales as a hard-core scientist might. In the Brothers Grimm story of Rapunzel, a witch holds a beautiful young woman captive in a tower. Rapunzel is blessed with a lovely singing voice and long, long blond hair. One day, her voice enchants a prince passing through a nearby forest. They fall in love, and Rapunzel lets down her hair so that the prince may use it to climb the tower to meet her. This chain of events begs readers to ask a question. Can human hair support the weight of another person? On average one strand of hair can support about three and one-half ounces, or about the weight of two candy bars. Each strand of dark hair is generally thicker, and therefore stronger, than blond hair. But, alas, Rapunzel must make do with blond locks. Given that blondes generally have about 140,000 hairs on their heads, her hair should easily support the weight of many, many princes. However, there is more to this story. If Rapunzel simply let down her hair and the prince started climbing immediately, her hair would not break, but it might rip out. Also, the rest of her body might not be able to support the weight. Thankfully, there are strategies that she can use to help reduce the strain on her head and body. Nathan Harshman, Assistant Professor of Physics at American University in Washington, DC, suggests Rapunzel would be safer and more secure if she tied her hair around something before lowering it. “The whole idea is that you can use the f riction of the hair against itself in the knot, and whatever it is tied around will support the weight of the prince.” That is a much better idea than making Rapunzel’s scalp the anchor point. In the Disney version of Hans Christian Andersen’s The Littl e Mermaid, Ariel asks a witch to make her human because she has fallen in love with a human prince. The witch bargains with Ariel and takes her voice in exchange for performing the transformation. For a considerable part of the story Ariel cannot speak, which is a problem because the prince can only recognize her by her incredibly beautiful singing voice. Later, she recovers her voice and wins the love of the prince . In the story, Ariel loses her voice because of a curse. However, a less skilled sorceress could use a different method to silence a singing mermaid. Scientists have figured out a way to bend sound waves around an object and, can even prevent the escape of all sounds created inside a given area . Recently, Steve Cummer, Associate Professor of Electrical and Computer Engineering at Duke University announced that it is theoretically possible to create such a sound shield. Building on research demonstrating how light waves can be bent around an object to make it appear invisible, Cummer and his