Reading 1 of 5
Light Cones: What Can Affect What in Spacetime?
Physics
Why it belongs
Open this readingBegin with the causal structure that sets the trail's foundation.
Reading Trail
Start Exploring Spacetime
Follow a path through light cones, spacetime intervals, cosmic time, and the questions that reshape our picture of the universe.
Begin the trail
The route
Along this trail
Reading 2 of 5
The Spacetime Interval: Timelike, Lightlike, and Spacelike Separation
Physics
Why it belongsOpen this readingTurn that picture into a way of classifying separation in spacetime.
Reading 3 of 5
If Time Is Relative, How Can the Universe Have an Age?
Physics
Why it belongsOpen this readingConnect relativity to a cosmic clock shared across the universe.
Reading 4 of 5
Where Is the Center of the Universe?
Physics
Why it belongsOpen this readingUse cosmology to rethink what a center would mean.
Reading 5 of 5
What Does “Spacetime Is Doomed” Actually Mean?
Physics
Why it belongsOpen this readingEnd at the frontier where spacetime itself may cease to be fundamental.
