Physics

Front 1

The Principle of Relativity

Back 1

– 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

Front 2

Principle of the Constancy of the Speed of Light

Back 2

– 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.

Front 3

Time Dilation

Back 3

• 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:

Front 4

Proper Time (TS)

Back 4

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

Front 5

Length Contraction

Back 5

• 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.