Skip to content
World 6 · Surfaces: twists, holes and curvature · 9 min · PRO

Total curvature counts holes

Euler characteristic and Gauss–Bonnet

PRO · Vector Lab

World 6: Surfaces: twists, holes and curvature is part of PRO

The first world of Vector Lab is free. PRO opens the other 21 lessons in 6 worlds — simulations, quizzes and all.

  • One side or two?
  • Bending you can measure from inside
  • Cut the Möbius strip
  • Light cones and the order of events
  • A moving clock runs slow
PRO includes
  • All 26 labs — every world, every lesson
  • Practice exams and certificates

$8.33/mo, billed yearly ($99.99) · or $39.99 monthly

Unlock Vector LabTry the free world
← Cut the Möbius stripLight cones and the order of events →

Report a mistake

What is wrong?
0 / 2000 · at least 10 characters
Sent along with your report
  • Page
  • About Total curvature counts holes — Vector Lab · vectors/surface-gauss-bonnet
Plus your browser type. Reports go to our support system; see the privacy notice.