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5 Cards in this Set

  • Front
  • Back
The Principle of Relativity
– All the laws of physics are the same for uniformly moving observers, called inertial observers.
– A system moving with a constant velocity is an inertial system.
– There is no such thing as absolute rest or absolute motion:
– Consequence: Motion is Relative, not absolute
Principle of the Constancy of the Speed of Light
– Light propagates in free space with a speed c that is independent of the motion of the source.
– The speed of light measured wrt an inertial system must be the same for all such systems.
– Consequence: Time is Relative, not absolute.
Time Dilation
• Time on a clock that is moving wrt an observer is seen to run slower than time on a clock that is at rest wrt that observer:
Proper Time (TS)
the time interval measured by an observer who sees the event begin and end in one place.
• It is always the shortest time interval.
• Observers in motion will measure longer time intervals
Length Contraction
• A moving observer measures an object to have a length along the direction of motion that is shorter than the length measured by an observer at rest wrt the object.
• This is called length contraction and it is mathematically identical to the the Lorentz-FitzGerald Contraction discussed earlier.