Physics in the Real World

Physics in the Real World — page 3 — D G APH 2008

Physics in the Real World — page 4 — CHAPTER ONE DISAPPEARING ACT In a laboratory a physicist can make things disappear He lines up four lenses They are like those found in eyeglasses But these lenses do not help a person see Instead they bend light around an object This makes that object appear invisible The physicist looks through the lenses It seems as though the object is not there at all P h y s i c s m a k e s i n c r e d i b l e t e c h n o l o g i e s s u c h a s i n v i s i b i l i t y possible 5

Physics in the Real World — page 5 — Professor John Howell and graduate student Joseph Choi developed this method of invisibility They did their research at the University of Rochester in New York The device cost them just 1,000 and they believe it can be made even more cheaply IN THE REAL WORLD Acoustic Cloaking Physicists are also looking for ways to hide objects from sound Such technology could fool sonar Sonar works by sending out a burst of sound When that sound strikes an object the sound wave bounces back The sonar system listens for the echo The timing of the echo tells the system how far away the object is Scientists can redirect these echoes This makes the object invisible to sonar Invisibility has long been a dream of science fiction writers Physicists are making those dreams come true Invisibility could have many uses The military could use it to hide troops It could also help in fields such as medicine A surgeon 6

Physics in the Real World — page 6 — Mirror Viewer L t h g i Cloaking Region Mirror Mirror Mirror Invisibility Technology This diagram shows how one simple method of invisibility works How does this help you better understand the cloaking technology What other uses can you think of for invisibility could see right through her hands into a patient’s body However this technology is difficult to use It is hard to make an object invisible from every angle Making moving objects invisible is also tough More work is needed to develop useful invisibility Many physicists are trying to solve this and other problems 7

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