What is Time Dilation?


"We take for granted that time ticks by at the same rate for everyone. But Einstein's special theory of relativity shows that this assumption is not strictly true. The classic case of time disparity involves twins - one of whom leaves Earth and travels round-trip to a star at nearly the speed of light, arriving back much younger than his bother. This aging difference is noticeable only when long distances are traveled at speeds approximating the speed of light" (Lasky).

Let's begin with a hypothetical situation. Somebody is on a super airplane that has the ability to travel at 299,792,457 meters per second (one meter per second less than the speed of light). Suddenly this person gets the urge to go to the bathroom. They get up and begin walking towards the bathroom(located towards the front of the ship). As soon as they go any faster than 1 meter per second the universe itself collapses, because the speed limit of the universe was surpassed. Clearly nothing can travel faster than the speed of light, and this is the very reason time dilation must exist. The aforementioned example involves time dilation due to a difference in velocities, but the same principals are at play for gravitational time dilation. Without a slowing of time something could accelerate towards a black hole at with an acceleration caused by the black holes gravity. The larger that acceleration due to gravity gets, the quicker the speed of light can be reached. Time itself must be slowed in order to prevent things from going faster than the speed of light. A speed buffer of sort exists to ensure that nothing can travel faster than the speed of light, this buffer is time dilation.

To be more specific, time dilation is the difference between the amount of time an event takes from two different reference frames. A clock on the International Space Station will run slightly slower than an exact copy of the same clock back on Earth. The difference has nothing to do with the clocks themselves, but with how space-time works. Time dilation is experienced by everything, from subatomic particles to planets and all other objects contained within the universe. Time dilation is important for many real world applications such as keeping time between Satellites and the Earth consistent. Neil Ashby goes into depth about the importance of time dilation in his article "Relativity in the Global Positioning System". "The Global Positioning System (GPS) uses accurate, stable atomic clocks in satellites and on the ground to provide world-wide position and time determination. These clocks have gravitational and motional frequency shifts which are so large that, without carefully accounting for numerous relativistic effects, the system would not work" (Ashby). Two types of time dilation exist; time dilation onset by a difference in relative velocity, and time dilation brought about by the effect of gravity.



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