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Natural Sciences · Advanced

Spacetime

Hermann Minkowski showed that Einstein's relativity is really geometry, in a four-dimensional spacetime. Learn to draw spacetime diagrams, find the interval that all observers agree on, map out light cones and cause and effect, add velocities relativistically, see why the travelling twin comes home younger, ride a 1 g rocket to the centre of the galaxy, and fit a ladder into a barn that's too short for it.

7 lessons~35 min0/7 complete
Start courseHelpful background: Special Relativity
1

The Geometry of Spacetime

Diagrams, intervals and light cones.

  1. Spacetime DiagramsDrawing motion through time
  2. The Invariant IntervalWhat everyone agrees on
  3. Light Cones & CausalityWhat can affect what
2

Relativity in Action

Velocity addition and the twin paradox.

  1. Adding VelocitiesRapidity: the hidden way speeds add
  2. The Twin ParadoxThe longest path is straight
3

Journeys and Paradoxes

Rockets to the stars and ladders in barns.

  1. Rocket to the StarsConstant acceleration across the galaxy
  2. The Ladder ParadoxSimultaneity to the rescue