Flat Earth Theory

Claim: The Earth is a flat disc, not a sphere, and space agencies, governments, and scientists worldwide conspire to hide this "truth," often through faked satellite imagery and space missions.

Origins: Modern Flat Earth belief traces to 19th-century English writer Samuel Rowbotham; it saw a resurgence in the 2010s via YouTube and social media communities like the Flat Earth Society.

Why it's false: The Earth's roundness has been established since antiquity — Eratosthenes calculated its circumference around 240 BCE using shadow angles. Modern evidence includes: ships disappearing hull-first over the horizon, different constellations visible from different latitudes, time-zone differences, circumnavigation, GPS satellite systems, and direct photographic/video evidence from thousands of independent sources including amateur high-altitude balloons.

Status: Universally rejected by science; considered a striking case study of how algorithm-driven social media can revive long-debunked ideas.