lightspeed(1) Shows how objects moving at speeds near the speed of light look like.


lightspeed [-hsa] [object]


Light Speed! is a simulator which can illustrate the effects of special relativity on the appearance of objects travelling at ultra-high speeds. Depending on the particular speed, and one's point of view, relativistic effects can cause the object to appear shorter, longer, brighter, darker, deformed and/or off-color.


To adjust the velocity, use the slider along the right edge of the main window. You can also type in a value, using the entry at the top right (press <Enter> once it is in). To change the units shown, press the button to the right of the entry, and it will cycle through a small list.

The object travels in the positive-x direction, which can be visually checked by activating Objects -> Coordinate axes.

Most interactive control is performed with the mouse. By holding down a particular button, and dragging the pointer around, various camera motions can be obtained:

   Left button:  Revolve camera around view target
   Left button + Shift key:  Revolve view target around camera
   Middle button:  Translate camera left, right, up or down
   Right button:  Dolly in or out

The first and last motions are generally the most useful. Should the camera become difficult to control at any point, it may be re-initialized by selecting Camera -> Reset View.


-h, --help
Print this help screen
-s, --simple
Use simplified interface
-a, --advanced
Use advanced interface (default)
3D file to load on startup (.3DS or .LWO)