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.
Next: Relative Velocity Time Dilation
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