Time Dilation in a Gravitational Field (Essay Sample)

TIME DILATION IN A GRAVITATIONAL FIELD
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Time Dilation in a Gravitational Field
Time dilation refers to the difference between a measured time interval of an event and its proper time interval. It arises when there is a difference in gravitational field strengths or relative uniform motion between observers. An observer in motion records a longer time interval for a particular event than a stationary observer. Similarly, an observer in a strong gravitational field records a longer time interval for an event than another observer in a weak gravitational field.
Time dilation caused by gravity is a phenomenon in which time passes at different rates as measured by two observers located in different gravitational potentials. The observer located in a strong gravitational field, where the events occur, measures a greater time interval while another observer in a weak field records a shorter interval. Indeed, if one observer is on the earth surface while another is in the International Space Station, the observer on earth would perceive a particular event as if it takes a longer duration. This is because of the way clocks run at different altitudes, where the strength of the force of gravity varies.[Peter Collier, A Most Incomprehensible Thing: Notes Towards a Very Gentle Introduction to the Mathematics of Relativity (Harlow: Incomprehensible Books, 2013), 270.] [Jack Stanfield, Modernity, a World of Confusion: Reality and Choice (S.I.: Xlibris Corporation, 2013), 100.]
A clock runs faster at a high altitude than in a low altitude because of the effect of gravity. The force of gravity induces a refractive index analogous to the one encountered by light traversing different media. This refractive index slows down a clock at a place where the gravitational field strength is high. However, in a place where the force of gravity is weak, the effect reduces considerably. Thus, two observers located at different altitudes essentially use clocks running at different rates to measure the duration of events. Since a fast-running clock indicates a longer duration for a particular event, time appears to pass faster to an observer at a high altitude.[Ta-Pei Cheng, Einstein's Physics: Atoms, Quanta, and Relativity - Derived, Explained, and Appraised (Oxford: Oxford University Press, 2013), 190.]
Time dilation due to gravity has been tested twice at macroscopic level. The first experiment was carried out by Richard Keating and Joseph Hafele. In the experiment, the two scientists flew atomic clocks in commercial airlines, one in the eastern and another in the western direction. They had predicted that the clock flown westwards would gain more time than the one flown eastwards because of the effect of earth’s rotation. During the analysis, the effects of the planes’ ascending, descending, and earth’s rotation were considered. Hafele and Keating discovered that time had dilated by 47 ns. This result was within 10% of Einstein’s prediction of time dilation, a considerably large error.[Friedel Weinert, The March of Time: Evolving Conceptions of Time in the Light of Scientific Discoveries (New York: Springer Science & Business Media, 2013), 73-74.]
Although the first test had a large experimental error, it provided a strong basis for the second experiment. The second experiment involved an atomic clock flown round Chesapeake Bay. It was done by scientists based in the University of Maryland. They flew a plane at a fixed altitude of 10 kilometers for 15 hours. Since the experiment was carried out with a high degree of accuracy, the results were very reliable. They verified time dilation within 1% of Einstein’s prediction. Thus, the scientists confirmed that gravity dilates time.[David Halliday, Robert Resnick, and John Walker, Fundamentals of P...