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**__The Theory of Relativity: It's Importance and Relevance__**
The Theory of Relativity greatly influences modern life today and is applied, referenced, and used by GPS, NASA, and the military.

Theory of Relativity developed by Jewish physicist Albert Einstein in 1916 -E=mc(squared): reveals equivalence of mass and energy-the speed of light is constant in a vacuum and is an absolute physical boundary for motion-when Einstein applied Theory to gravitational fields, he derived "curved space-time continuum"-first is Special Theory of Relativity-Special Theory of Relativity deals with whether rest and motion are relative or absolute, and Einstein concluded they are relative-second is General Theory of Relativity-General Theory of Relativity deals with particles as they accelerate, specifically due to gravitation-General Theory acts as radical revision of Newton's theory-General Theory reproduces all predictions of Newton's theory, but expands on our understanding of the key principles-Einstein's theories of Special and General Relativity confirmed accurate to very high degree recently -data from confirming Einstein's Theory of Relativity corroborates many key predictions; most famous in 1919 solar eclipse providing evidence that light of stars is deflected by sun __GPS and the Theory of Relativity__ GPS, global positioning satellites, was created by the United States Department of Defense in order to provide the U.S. military with a reliable satellite-based navigation system. The present-day GPS system consists of 24 satellites in high orbits around the Earth, each travelling at 14,000 kilometers per hour at an altitude of 20,000 kilometers. An atomic clock equips each satellite with the time and each clock has an accuracy of one nanosecond, or one one-billionth of a second. Every single GPS device has phenomenal accuracy and precision and can pinpoint a person's location on the earth to within ten meters in only seconds. Obviously, this is an important system for the United States government as well as the rest of the world, and it would not have been possible without the application of Einstein's Theory of Relativity. GPS uses Einstein's Special Theory of Relativity in that since an observer on the ground sees satellites in motion relative to them, ultimately the expectation would be that their clocks would tick more slowly. Using Special Relativity, scientists and engineers predict that the atomic clocks on-board the satellites should fall behind clocks on the ground by roughly 7 microseconds per day. This is found by assuming that the atomic on-board clocks will have a slower ticking rate due to the effects of their relative motion. Einstein's General Theory of Relativity is also applied to GPS, but in a different way. One of the predictions that sprouted from the General Theory of Relativity was that clocks closer to a massive object will tend to tick more slowly than those further away. Therefore, from the viewpoint of the surface of the earth, the satellite clocks seem to be ticking faster than the clocks on Earth's surface. Using the General Theory of Relativity, scientists and engineers have calculated that the satellite clocks should get ahead of the ground clocks by 45 microseconds per day. Using the combination of the two, it was determined from the Theories that the satellite clocks should tick faster than the clocks on the ground by 38 microseconds per day. While this sounds extremely small and meaningless, it makes an enormous difference, especially over time. Scientists and engineers heeded these predictions and ideas and included the effects due to relativity into their creation of the GPS system. Before they launched the satellites, they slowed down the ticking of the atomic clocks to act against the effects predicted in the General Relativity Theory. Also, each GPS receiver has a microcomputer built into it. These microcomputers take into account the calculations dealing with relativity when they calculate coordinates of a location. If the factors provided by the Theory of Relativity were neglected and not taken into account, GPS systems would be wrong after only two minutes and would have accumulating errors of 10 kilometers per day. That means after one month, they would be off by 310 kilometers. None of these factors would have been taken into account without the Theory of Relativity. However, thanks to Einstein and his abstract thinking and postulating, modern-day people have the joy of extremely advanced technology, particularly satellites that tell them exactly where in the world they are. Global positioning satellites would be an epic failure and would have constant calculating errors were it not for Einstein's Theory of Relativity. __NASA and the Theory of Relativity__ The theory of relativity is extremely important to space programs such as NASA. NASA and other programs working with the solar system deal with enormous vast open spaces and lots of time that would be required to cross or traverse those spaces. Obviously, it is important for an organization responsible for sending humans into the solar system to know exactly what they are doing and why. Measurements have to be as precise and accurate as possible. They need to be triple-checked again and again. Measurements need to be both precise and accurate with no mistakes whatsoever. Due to the need to be extremely correct and precise, NASA decided to test Einstein's Theory of Relativity. In 2004, NASA and Stanford University teamed up to come up with a way to test the Theory. They decided to send a probe into outer space that would be equipped with many computers and databases that could take accurate measurements of speed, time, acceleration, position, and many more extremely important measurements. They designed a probe as their relativity experiment and named it Gravity Probe B. On April 20, 2004, NASA launched Gravity Probe B from Vandenberg Air Force Base in California. Gravity Probe B spent 17 months orbiting Earth and collecting data. That data is still under intense review and application to this day with no glaring conclusion yet as to Einstein's theories. However, whatever the final verdict and outcome, NASA is extremely interested in the theories and is willing to work and spend money to find out for sure. Gravity Probe B was equipped with gyroscopes that NASA created to have astonishing precision and accuracy. Each gyroscope is equipped to detect tiny changes of any angle with the accuracy measured to be one ten-thousandth of a degree. That is equivalent to a person looking at a single strand of human hair that is ten miles away. In the end, the overall results of Gravity Probe B's analysis will either agree or disagree with the Theory of Relativity.

Even though it is just a theory and not quite proven enough to be a scientific law, NASA has greatly taken the Theory of Relativity into account many times during many important flights and missions. The two effects that Gravity Probe B's data tested were the geodetic effect and framedragging. In the geodetic effect, Earth is believed to warp the space time in the part of space around it. In framedragging, Earth's rotation is believed to actually drag local space time around with the earth as it rotates on its axis. One main concept of Einstein's General Theory of Relativity is that the universe is actually four-dimensional. It is believed that space and time are inseparable. Also, any huge or massive solid such as Earth is capable of warping time in the space around it just by existing.

__Military and the Theory of Relativity__ The United States military relies heavily on Einstein's Theory of Relativity in many of the important tasks that they do. For starters, GPS, or global positioning satellite, was initially created to benefit the military with up-to-the-second pinpoint tracking of where people and things were. It was not, as many people believe, originally made for automobile drivers who cannot find their way to their destination. It was for the military, so it was important that GPS was accurate and precise. Therefore, when the GPS was created Einstein's Theory of Relativity was taken into effect. Also, the SI second, as determined by the military, takes into account Einstein's relativity. A popular type of time is General Relativity (GR) coordinate time, in which the time is taken by a slow-moving, weak-field metric. This time value covers the entire solar system and applies everywhere. Taking into account Einstein's Theory of Relativity, the actual time elapsed on a moving clock does not solely depend on how many seconds have passed. It also depends on the clock's position and velocity. It also must take into account the clock's position and velocity compared to nearby solid masses. The velocities and positions of the masses themselves are also a major factor of the time elapsed. Ultimately, the elapsed coordinate time as found by using the Theory of Relativity is computed by inputting the aforementioned values and making the necessary adjustments to the proper time as found on the clocks. The military uses the Theory of Relativity to keep time and to navigate, two of the most important things for military personnel. Without time or navigation, the military would struggle to accomplish much of anything.

The Theory of Relativity has a massive impact on modern-day life, and it is implemented by GPS, NASA, and the United States military. Relativity was an enormous theory when Einstein discovered it in 1916, and it impacts human life to this day. Over time, the Theory has not fizzled out or become forgotten. If anything, the Theory of Relativity is respected more nowadays than when Einstein first announced it. It is considered by enourmous corporations and groups when they take on their most difficult tasks. It is not an official law of science, but many people treat it like one. It was implemented in the creation of global positioning satellites, which is most unusual. Many if not all other theories would merely be considered for a project, but only the Theory of Relativity is actually implemented without having enough definite proof to make it a legitimate scientific law. It is not, as many believe, a wild, whimsical guess by Einstein. He was not imagining things or trying to recreate the universe. He was simply making an extremely cognitive observation that those around him were too ignorant to understand. To this day, it is amazing to think that someone could just discover something like the Theory of Relativity. The Theory does apply to modern-day life, it is important, it should not be ignored or disregarded, and it is possibly the most important and vital scientific discovery ever.

__Works Cited__: "Special Relativity." //Virtual Visitor Center//. SLAC. 26 Jan. 2009. http://www2.slac.stanford.edu/vvc/theory/relativity.html.

Ashby, Neil. "General Relativity in the Global Positioning System." University of Colorado. 23 Jan. 2009. http://www.leapsecond.com/history/Ashby-Relativity.htm.