October 3, 2022

The GPS is one of many that the current world relies on. From transportation to delivery services, almost everyone benefits from it in some way or the other. The GPS itself is based upon GPS satellites that orbit the Earth about 20,200 km (or about 12,600 miles) above the surface at a speed of about 3.9 km per second. Due to this, a certain effect called time relativity comes into play. Albert Einstein originally discovered time relativity in his 1905 paper titled “theory of special relativity”.

Time relativity states, “The quicker an object moves through space, the slower it moves through time relative to an observer”. Although this might initially be a bit confusing, we can imagine an experiment to make it more clear. Say you have twins, born simultaneously. One twin is kept on Earth, leading a normal life and the other is put on a spaceship. This spaceship is moving at 99% the speed of light towards outer space. When the twin on Earth turns about 80, the twin in space will turn 1. The more mind-blowing thing about this is that neither of the twins will experience time differently, they will both experience seconds, minutes, hours, days, months, and even years the same as everyone else.

How does time affect everyday life?

Although this might seem like a very foreign concept that does not affect everyday life, it very much does. The previously mentioned example of GPS satellites is a very good example of this. Due to their very fast speed (3.9 km/s), they are often subject to time being slowed at about 8 microseconds per day. Although you may be confused as to why such a small number would matter, these imperfections are what cause google maps to tell you you are on top of a mountain in Japan when in fact you are in a convenience store in the UK. To correct this, a prewritten formula is applied during data transmission to get the timings perfect according to time on Earth. 

Another example of this could be astronauts, like in the movie Interstellar. Interstellar was based on the concept of  “Gravitational time dilation”, which is slightly different from time dilation. Because gravity can bend the fabric of spacetime, it can bend time itself. The closer someone is to a mass of gravity, such as a planet, the quicker time passes. In Interstellar, the astronauts land on the planet called “Miller’s planet”. Miller’s planet is on the edge of a black hole, close to the event horizon and in orbit. Black holes have gravity so strong that even light cannot escape them. This means that time on the planet was so fast that 1 hour on miller’s planet is 7 years on Earth, which results in 1.25 seconds on the planet being 1 day on Earth. 

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