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“Okay,” Uncle Gus agreed. “That’s a great place to start.” The sign over the cars said “ Autonomous Cars.” The cars looked similar to any other car that might be driving around the block. Maybe a little sleeker, a little more streamlined, but not any- thing dramatic. There was a device mounted on the roof of each car, and upon looking inside, Emmett saw a large computer screen near the passenger seat and some strange controls. An engineer was explaining to a group of people how the car worked when Emmett and Uncle Gus came up. “This car uses three things: a laser scanner, a GPS , and a series of cameras,” the engineer said. “These three devices are hooked to the car’s computer and work together to allow the car to navigate safely through complex courses. “Up here on the roof of the car is the laser sensor. This constantly scans the area around the car. The laser hits objects, and bounces back a signal to the sensor to estimate how far away the objects are.” A girl in the audience interrupted, saying, “Isn’t that how a bat does it?” The engineer nodded. “Yes, basically, but a bat uses reflected sound waves in a process called echolocation. They send out ultrasound waves, which bounce off distant objects and travel back to their ears. This tells the bat how far away objects are so they can avoid obstacles or catch the mosquitoes they are after.” “Is that sonar ?” someone asked. The engineer laughed. “Wow. Tough crowd today. Sonar is sound navigation and ranging . It is used to find objects under water. A laser uses light. In fact the word laser isn’t actually a

word. It represents the phrase light amplification by stimulated emission of radiation . In other words, light becomes stronger when it is exposed to electromag- netic radiation .” He pointed at the device on top of the car. “The laser is constantly monitoring the dis- tances between objects and the car. There is a GPS, of course, which pinpoints the exact loca- tion of the car on a map. Other equipment, like cameras, help keep the passengers and others on the road safe.”

autonomous able to act alone and without guidance electromagnetic radiation energy passed through space by electromagnetic waves GPS Global Positioning System, a direc- tion-finding method that uses informa- tion from satellites orbiting the Earth laser an intensified beam of light sonar a system that uses sound to find directions and locations underwater Words to Understand

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