Quote:
Originally Posted by sjastro
That's correct. Consider a rod travelling along the direction of the length of the rod.
The rod undergoes length contraction. The diameter of the rod which is a dimension perpendicular to the direction of motion remains unaltered.
The pdf is showing 2 Minkowski diagrams. The length contraction is based on the stationary observer's frame of reference.
In the stationary frame of reference the time and spatial axes are perpendicular or orthogonal. In the sticks frame of refernece which is moving relative to the stationary observer the axes are rotated and are now less than 90 degrees to each other. The faster the stick moves the greater the rotation of the axes. The lines intersecting the ends of the sticks are parallel to the rotated time axis. Since the lines run parallel to the time axes the ends have been simultaneously measured. The sticks are located over the rotated spatial axis.
The projection of the lines onto the rotated spatial axis gives the contracted length.
Regards
Steven
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Cool. Thanks Steven.
I think I'm getting the knack of this !!
I find these spacetime diagrams really help out.
The ones they use to describe black holes are really cool, also.
They can explain lots of things on the one diagram.
Cheers