‘History’s most precise experiment’: How Henry Cavendish weighed the Earth with just two lead balls in a closed room

Scientists long pondered Earth’s weight, an impossible task with conventional scales. In 1798, Henry Cavendish, using a modest torsion balance with lead balls, ingeniously measured the faint gravitational pull between them. This groundbreaking experiment revealed Earth’s density, finally allowing its mass to be calculated, a feat still admired for its precision and ingenuity.