<    1    >

### Event

Each point in a space-time diagram is called an event.

##### Frame of reference at rest

Minkowski diagrams provide an illustration of the properties of space and time in the special theory of relativity. The distance is displayed on the horizontal axis and the time on the vertical axis.

The time axis does not show t, but ct, where c is the speed of light. Thus one second corresponds with 299 792 458 m. For a lightparticle passing the origin of the coordinates to the right applies x = ct, and this yellow worldline makes an angle of 45°, because the same scale has been chosen for both coordinate axes.

##### Frames of reference in motion

In the drawing below there are three frames of reference.

The black frame is at rest. The primed frame moves at 40% of the speed of light, and the double primed frame at 80%. Note the scissors-like change as speed increases.

##### History

The Minkowski diagram was developed in 1908 by the German mathematician Hermann Minkowski.