E=MC^2 In Every Day Life

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Without Relativity, GPS Would Be Lost

http://insights.globalspec.com/article/156/without-relativity-gps-would-be-lost

If anyone wonders if Einstein’s theory of relativity has any practical application all they have to do is look at the GPS function on their phone.

This article explains how the GPS satellites have sophisticated algorithms that account for a practical application of Einstein’s theory. We don’t think about it much. Some of us have heard about things like red shift and a few people can almost understand why a train whistle sounds different when the train is approaching than it does when receding. But how many of us understand that the speeds and distances involved in GPS satellites would be very inaccurate if they didn’t account for the effects of relativity.

Because of the altitude of the orbit, the gravitational effect on the satellite is different than on the earth and that causes time for the satellite to move a little slower. Also, because a satellite in orbit is constantly accelerating, (a satellite is constantly falling ‘around’ the Earth) time runs a little slower. Other movement factors like the fact that the Earth is moving around the Sun and the Sun is also moving also contribute to the effects on time relative to the satellite.

All of these factors are explained by Einstein’s theories and they must be accounted for in the precise timing of a GPS satellite. So we see examples of Einstein’s theories every time we use a GPS device.

In science fiction writing, I’m afraid many authors disregard these little examples of relativity. True they are tiny when applied to a GPS satellite, but they could be much larger in a practical application within a sci-fi story. Space travel of any major distance at near light speeds would require a total disconnect with people on Earth. If an astronaut made such a trip and returned they would find their contemporaries dead or much older.

This time effect is what would make worm holes such a nice way to travel. A traveler could jump from ‘here to there’ which no loss in time at Earth.

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