Time
............................................................................................
What time is it?
parameters such as speed and gravitational
A question cannot be simpler. It is 11.00 p.m. field at the location of the observer.
now, at the time of writing. It only involved
checking the clock.
Time dilation
Speed dependence of time is called time
dilation. In special relativity, an observer
What is time?
This is the real question, which scientists and in non-accelerating motion has a well-
physicists have been trying to answer for defined means of determining which event
occurs simultaneously with a given event.
centuries.
An accelerating observer, who is in relative
By simple means, time is the duration motion with the first, will observe different
between two past events. The clock now says events occurring simultaneously with the
it is 11.02 p.m. Therefore, the time passed is given event. This is used to predict 'slowing
2 minutes. During that time this article was down' of time in accelerating motion with
being written, time was felt to be moving respect to another.
smoothly in the background. It neither went
back nor crept forward.
Hafele and Keating Experiment
In 1971, US Naval observatory conducted
In classical mechanics, time is regarded as the Hafele and Keating experiment to test
an absolute characteristic of our universe, time dilation theory and gravity dependence
independent of the location. It is considered of motion predicted by the theory of special
as a straight passage of events that defines relativity.
past, present and future, which is similar to
Four Cesium beam clocks were flown around
real life experience.
the world twice in commercial airline jets and
compared with the ground-based reference
Time & the theory of relativity.
clock of the observatory in Washington.
With the introduction of Einstein's theory of
The clocks actually showed differences
relativity in the early 1900s, the idea of time
in time, which were comparable with the
changed drastically.
values suggested by Einstein's theory of
The theory proved that the time difference relativity. The theory of relativity was proven
between two events totally depends on experimentally.
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University of Peradeniya GAUGE Magazine