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Spacetime diagrams
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Plots of ct versus x show light cones and worldlines.
Plot ct versus x: worldlines trace motion, light moves at 45°, and the lines of constant time of a moving frame tilt. They make simultaneity and causality visual.
A stationary object has a vertical worldline.
Slopes steeper than 45° are physical for matter.
In more detail
Spacetime diagrams plot time against position to show the paths of objects and light. Light paths form diagonal lines at 45 degrees in units where c equals one.
Real-world uses
- Relativity courses use spacetime diagrams to explain simultaneity.
- Physicists visualise particle decays using these diagrams.
- Physicists draw spacetime diagrams to show how events and light signals are related in different frames.
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Frequently asked questions
What is a worldline?
The path of an object through spacetime.
Why do light paths form diagonals?
Because light moves at c, so its path covers equal space and time increments.
What is a worldline?
The path an object traces through spacetime, showing where it is at each moment of time.
Related topics in Relativity
Velocity addition · Muon decay evidence · Twin paradox · Spacetime interval · Light cones and causality · Proper time