🕰️ Relativity — Intro#

Scope — How measurements of space and time depend on motion and gravity, reshaping classical notions of simultaneity and distance.

Key concepts#

• Relativity — framework describing how space, time, and motion are interrelated.
• Reference frames — observers in relative motion may measure different times and lengths.
• Constancy of light speed — speed of light in vacuum is the same for all inertial observers.

Seed Q&A triads#

• Q: Why was relativity needed beyond classical mechanics?
  A: Classical mechanics could not reconcile observations involving light and high‑speed motion.

• Q: What is a reference frame?
  A: A coordinate system used by an observer to measure positions, times, and motions.

• Q: Why is the speed of light special?
  A: It is invariant across all inertial frames, forcing revisions to concepts of time and space.

Quick activities#

• Compare how two observers moving relative to each other might disagree on whether two events occur simultaneously.