25 Famous Experiments

Eratosthenes used geometry and the sun's angle at Syene and Alexandria to estimate the earth's circumference, with 7 degrees 4 minutes indicating about 1/50 of the globe.

Galileo shows that falling bodies reach the ground at the same time regardless of mass under gravity. The lecture traces incline experiments and the moon hammer-feather test confirming mass independence.

Roemer first proved that light has a finite speed by timing Io's eclipses and emergences, revealing a cumulative delay over orbits corresponding to about 220 million meters per second.

Follow how James Lind's 1747 clinical trial showed oranges and lemons cure scurvy during long sea voyages, linking vitamin C to gum health and survival.

Lavoisier challenges the phlogiston theory by showing a breathable gas in air, later named oxygen, that supports combustion and respiration, building on Priestly's combustion observations.

Trace how Alessandro Volta created the first battery from early electricity work and the animal electricity debate, using a zinc-silver pile with an electrolyte to form anode, cathode, and discharge.

Edward Jenner demonstrated that cowpox vaccination provides immunity to smallpox, introducing the world's first vaccine and earning him the title of father of immunology.

Explore how Thomas Young challenged Newton’s corpuscular theory by revealing light's wave-like interference in the double slit experiment. Learn how diffraction, reflection, refraction, and interference demonstrate light’s dual nature.

Hans Christian Ørsted demonstrated that an electric current creates a circular magnetic field, establishing the link between electricity and magnetism and underpinning the foundations of the modern digital world.

Lucretius described dust dancing in light, and Robert Brown first observed pollen grains jittering in water; Einstein later linked this random motion to moving atoms and molecules in fluids.

Explore how Faraday demonstrated electromagnetic induction by a changing magnetic field inducing current in a conductor, using a moving magnet and a coil connected to a galvanometer.

Explore how the Doppler effect changes perceived pitch as ambulance sirens approach and recede, due to shifting frequencies and wavelengths of sound waves.

Léon Foucault demonstrates Earth's rotation with a heavy pendulum, showing its plane of oscillation stays fixed as the earth rotates beneath it, varying with latitude and poles.

Explore the concept of evolution, from Greek ideas to Lamarck and Darwin. Learn how natural selection, overproduction, variation, and the struggle for existence drive descent with modification.

Gregor Mendel's peas experiments reveal Mendelian inheritance, showing how alleles segregate and assort, with dominant and recessive traits, produce a 3:1 phenotypic ratio in F2.

Explore the history of spontaneous generation, from ancient beliefs and Redi's meat experiments to Pasteur's swan-neck broth proof that life arises from existing life.

Darwin and his son showed phototropism arises from light perception at the shoot tip, guiding stem bending toward light via auxin-driven growth.

Explore how Maxwell linked electric, magnetic, and light waves into one theory and how Hertz experimentally confirmed electromagnetic waves, laying the groundwork for radio and wireless communication.

Pioneering serum therapy, researchers Behring and Kitasato immunized animals to produce antitoxins against diphtheria and tetanus, demonstrating effectiveness in early human trials.

Explore the discovery and impact of radioactivity, tracing how polonium and radium emerged from uranium research, led by Marie and Pierre Curie, and their Nobel Prize legacy.

Explore how classical conditioning links neutral stimuli like a bell or lab coat to unconditioned stimuli such as food, triggering conditioned salivation in dogs and humans.

Heike Kamerlingh Onnes discovers superconductivity in mercury, revealing zero electrical resistance below a critical temperature; he later shows lead also superconducts, and that magnetic fields destroy the effect.

Alexander Fleming discovered penicillin after mold contaminated a culture, and in the 1940s researchers scaled its production to create a life-saving antibiotic.

Frederick Griffith demonstrated the transforming principle by transferring genetic material from heat-killed smooth pneumococcus to rough strains, enabling transformation and capsule formation.

Karl von Frisch reveals how the waggle dance communicates food sources and nesting sites among honeybees, encoding direction, distance, and resource quality through two dance phases, with sun cues.