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From lenses to GPS: precision science drives the world

2018-06-29 439

In October 1957, the former Soviet Union launched the Sputnik 1 satellite (Sputnik 1, the first human satellite). Within a few days, several experts, including William Guier and George Weiffenbach from Johns Hopkins University, tracked the satellite by monitoring radio signals. By launching the experience of tracking missiles at sea, they realized that by monitoring the Doppler shift of the radio signals emitted by the satellite during motion, one can not only determine whether the satellite is moving forward or backward relative to the signal receiving station, but also Its relative position to the signal receiver.

They proved this discovery, but in the near future they were called to the office by the boss. Their boss explained that if the person on the ground can determine the position of the satellite by precisely monitoring the frequency of the satellite, then vice versa: a radio signal from a satellite operating in a known orbit can be on the ground or People at sea determine their position with great precision. The initial error value was about 300 feet, but eventually it could be reduced to about 60 feet. This discovery led to the establishment of the US Navy's Meridian satellite navigation system (Transit), and also laid the foundation for the formation of the Global Positioning System (GPS) decades later. Today, GPS has been able to locate your car with a few feet of error. With specific GPS components, GPS can also activate the plotter to locate anywhere on the planet with a few millimeters of error (although this process may take some time).

Simon Winchester's new book, The Perfectionists: How Precision Engineers Created the Modern World, focuses on similar stories. In the book, the author explains how the pursuit of precision has repeatedly led the advancement of technology. To enable the US Navy to accurately locate missiles with nuclear warheads, Johns Hopkins' Applied Physics Laboratory and Meridian Satellite Navigation System reduced the positioning error to within a few hundred feet. In order to make the delivery of traditional bombs more precise, GPS needs to be more precise; in order to identify different plots, the plotter needs higher precision; in addition, photographers and scientists also have their own instruments. The higher the accuracy requirement. The pursuit of precision has appeared both at the mathematical and physical levels - it is the more precise mathematical operations that make the Meridian satellite navigation system and the global positioning system work, and the hard materials such as metal and glass with higher precision have become more versatile. control.

"perfectionist" 

In this book, Simon Winchester introduces the different stages of human pursuit of precision: in 1776, British industrialist John Wilkinson developed a steam engine with an accuracy of one-tenth of an inch; In the Laser Interferometer Gravitational-wave Observatory in Washington State, the tolerances of scientific instruments have been extremely small - in 2015, the instruments here successfully detected gravitational waves. In addition, the author also mentioned the precisely adjusted Rolls Royce engine, Leica camera and the expensive Leica lens. Of course, there is also the Hubble Space Telescope, whose carefully tuned lenses were found to have major problems immediately after launch. In the author's words, its lens "has been carefully adjusted to a fault condition." However, the Hubble telescope was later properly repaired and is now widely regarded as one of the greatest scientific instruments of all time. Its popularity is almost equal to that of Einstein and Shakespeare.

According to Simon Winchester, smartphones are not only the most popular precision instruments in the world, but also the most sophisticated instruments that people can access in their daily lives. This title is hard to come by because mobile phones are not mechanical devices but electronic devices. equipment. The components inside the phone are compactly welded together and there is no room for movement. The case of the Samsung Galaxy Note 7 phone proves that high precision sometimes becomes a problem. The battery tends to inevitably swell slightly, but the phone's internal design is too compact, leaving no room for battery expansion. Therefore, this phone may catch fire and explode after charging a large amount of electric energy.

According to the different stages of human pursuit of precision, the book is written in a very logical way; for the pursuit of precision, it is clear and accurate. Grinding out near-perfect optical lenses and creating highly accurate timing devices requires decades of continuous improvement of the machine itself; accuracy is a step-by-step process, and every important development in this area is often It took many years.

Simon Winchester also issued a warning: There is a belief that the more precise the better, the pursuit of precision is almost cult, but it is not necessary, because the certain precision is sometimes sufficient to meet the demand, and the cost is lower. Throughout the book, the author tells about the various precision equipment and instruments he has encountered over the years: in England in the 1950s, his father showed some of the precision instruments made of metal to the children who were still in his childhood - that It is a set of tools for calibration. In his early 20s, he worked at a marine research company serving the oil industry, where he was responsible for pinpointing a drilling facility at the bottom of the English Channel. After referring to the radio positioning device, he successfully inserted the pillar of the giant device into the sludge with an error of less than 200 feet. Eventually, the device successfully landed in the expected position. The company's people told him that as a newbie, his first homework was done quite well. Today, his performance is probably ridiculous, because the error distance between the actual placement of such drilling equipment and the planned location is now only a few centimeters. He said that the accuracy improvement in this case will not bring much change, but the pursuit of precision has made the oil industry really go to this step today.

This theme is hard to tell, because high precision is the common pursuit of many aspects of manufacturing and technology. Therefore, Simon Winchester had to make a choice in the book. He also pointed out one aspect that the book could not reach - confidential intelligence gathering equipment. Accuracy is also important for the advancement of such equipment. While William Guier and George Weiffenbach are working on physics labs to provide satellites that provide precise positioning for the US Navy, other scientists and engineers are developing their own technologies at the Naval Research Laboratory in Washington. -- Use satellites to locate Soviet radars and other launchers, or capture weak radio signals from Soviet intercontinental ballistic missiles during flight tests from a strong electromagnetic signal environment.

The field of precision science is very broad, and it is difficult to see the whole picture of it - but this situation is sometimes caused by the will of the government.

The author, Dwayne Day, is active in Washington, DC and is an expert in civil space and aviation. His other writings also cover the history of human beings gathering intelligence from space.