#OnThisDay Sept 23, 1877, Urbain Le Verrier passed away.
He was the brilliant French mathematician who predicted the existence of Neptune using mathematics—before it was ever observed through a telescope! 🔭
Let’s explore his genius and legacy. 🧵 In the early 1800s, astronomers noticed strange deviations in Uranus’s orbit that Newton’s laws couldn’t explain.
Was Newton wrong—or was something else tugging at Uranus?

#OnThisDay Sept 22, 1776é American patriot Nathan Hale, a 21-year-old captain in the Continental Army, was executed by the British in New York City for espionage during the Revolutionary War.
Read full 🧵 👇 Hale had volunteered to go behind enemy lines to gather intelligence on British troop movements during the New York campaign. Disguised as a Dutch schoolteacher, he operated on Long Island.

#OnThisDay, Sept 20, 1952 — Alfred Hershey & Martha Chase published an experiment that transformed biology. 🧬
They showed that DNA, not protein, is the genetic material — using just a virus, a blender, and clever labeling.
Read full 🧵 👇 The Big Question (1950s):
What carries genetic information?

Proteins: complex, diverse, seemed a better candidate.

DNA: simple, repetitive, thought too “boring.”
Most scientists bet on proteins.

#OnThisDay in 1849, Harriet Tubman, the American abolitionist later known as the “Moses of her people,” made her first attempt to escape slavery from a plantation in Maryland.
Read full 🧵 👇 Tubman was born into slavery as Araminta Ross around 1822. Facing the constant threat of being sold, she decided to take the dangerous journey north toward freedom.

#OnThisDay September 12, 1958, Jack Kilby at Texas Instruments demonstrated the first working integrated circuit — a tiny invention that laid the foundation for modern electronics and computing.
Read full 🧵 👇 At the time, electronics faced the “tyranny of numbers.” Circuits required thousands of individual components (resistors, capacitors, transistors) soldered together, making devices bulky, costly, and prone to failure.

#OnThisDay September 9, 1947, engineers at Harvard University discovered something unusual inside the Harvard Mark II computer. Not a coding mistake, not a glitch… but a real bug.

Read the full thread to know the story of the first computer bug ... While running diagnostics, the machine suddenly malfunctioned. Upon inspection, engineers found a moth trapped inside one of the computer’s relays. The insect had literally caused the failure.

#OnThisDay September 4, 1998, Google was founded by Larry Page and Sergey Brin, two PhD students at Stanford University. What began as a research project became one of the most influential tech companies in history.
Read full 🧵 👇 Larry and Sergey’s mission was simple yet ambitious:

“To organize the world’s information and make it universally accessible and useful.”
Their search engine quickly outperformed existing ones by ranking pages based on links (PageRank).

#OnThisDay August 8, 1902, Paul Dirac was born — one of the greatest theoretical physicists of the 20th century.
He predicted the existence of antimatter and reshaped quantum theory with a blend of logic and beauty that stunned the scientific world.
A thread 🧵 Dirac was known for his mathematical elegance and minimalism — both in his equations and in speech.
His 1928 Dirac Equation unified quantum mechanics and special relativity, and predicted a particle identical to the electron but with a positive charge — the positron.

#OnThisDay July 29, 1818 — French physicist Augustin-Jean Fresnel submitted his "Memoir on the Diffraction of Light" to the French Academy of Sciences.
It would become one of the most influential papers in the history of optics. 🧵⬇️ At the time, the particle theory of light, championed by Newton, still dominated. Fresnel, however, built on Thomas Young’s earlier work to argue forcefully for wave theory—using mathematics, experiments, and brilliant insight.