The birth of quantum theory December 14, 1900

ON this day, German physicist Max Planck publishes his groundbreaking study of the effect of radiation on a “blackbody” substance, and the Quantum Theory of Modern Physics is born. In 1918, Planck was rewarded the Nobel Prize in physics for his work on blackbody radiation. Today, the combination of quantum mechanics with Einstein’s theory of relativity is the basis of modern physics.

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THIS day, the leaning Tower of Pisa, in Italy reopens after a team of experts spent 11 years and $27 million to fortify the tower without eliminating its famous lean.

The lean was discovered as earlier as 12th century, when the Tower of Pisa was still under construction and the foundation began to sink into the soft, marshy ground, causing it to lean to one side. Its builders tried to compensate for the lean by making the top stories slightly taller on one side, but the extra masonry required only made the tower sink further. By the time it was completed in 1360, modern-day engineers say it was a miracle it didn’t fall down completely.

However, the tower was closed in 1990 in order to fortify it.

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ON this day, near Kitty Hawk, North Carolina, Orville and Wilbur Wright make the first successful flight in history of a self-propelled, heavier-than-air aircraft. Orville piloted the gasoline-powered, propeller-driven biplane, which stayed aloft for 12 seconds and covered 120 feet on its inaugural flight.

Orville and Wilbur did not attend college, but they possessed extraordinary technical ability. They built printing presses, opened a bicycle sales and repair shop. Soon, they were building their own bicycles, and this experience, combined with profits from their various businesses, allowed them to pursue actively their dream of building the world’s first airplane.

The historic brothers’ aircraft of 1903 is on permanent display at the National Air and Space Museum in Washington, D.C.