A few years ago, a young man to whom I had just been introduced told me that I had saved his life. I hardly knew who he was. "More properly, GPS saved my life," he continued, "and since you had so much to do with GPS, in a very real sense you saved my life." It turned out that the man had been sailing with friends in the English Channel when fog had suddenly descended. Being in possession of a GPS (Global Positioning System) receiver, the crew members were able to find out exactly where they were and, better still, which direction was home.
Although to describe the event as "life threatening" might have been a bit of a stretch, this episode does at least provide a clear example of how important GPS is in today's world. Born out of the US military's desire to improve navigation, GPS was the world's first generally available satellite-navigation system.
In the October issue of Physics World, Roger Easton tells the story of how he came to invent GPS in the 1960s, and how versions by other countries are in the pipeline.
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