1822day.year
French physicist Augustin-Jean Fresnel, in a memoir read to the Academy of Sciences, coins the terms linear polarization, circular polarization, and elliptical polarization, and reports a direct refraction experiment verifying his theory that optical rotation is a form of birefringence.
In 1822, Augustin-Jean Fresnel introduced the concepts of linear, circular, and elliptical polarization and demonstrated optical rotation as a form of birefringence.
On December 9, 1822, French physicist Augustin-Jean Fresnel presented a groundbreaking memoir to the French Academy of Sciences. He introduced the terms linear, circular, and elliptical polarization to describe the various vibrational modes of light waves. Fresnel conducted a pivotal refraction experiment proving that optical rotation in crystals arises from birefringence. His findings provided compelling support for the wave theory of light over the prevailing particle model. The work revolutionized the study of optics and laid the theoretical foundation for modern photonics. Fresnel’s insights continue to underpin contemporary research in polarization and optical technologies.
1822
Augustin-Jean Fresnel
Academy of Sciences
linear polarization
circular polarization
elliptical polarization
optical rotation
birefringence
1868day.year
The first traffic lights are installed, outside the Palace of Westminster in London. Resembling railway signals, they use semaphore arms and are illuminated at night by red and green gas lamps.
On December 9, 1868, London saw the installation of the world's first traffic lights outside the Palace of Westminster, using semaphore arms and gas lamps.
Innovator John Peake Knight designed the traffic signal system based on railway semaphore technology.
The device featured pivoting arms to control vehicle movement by day and red and green gas lamps by night.
Installed near the Houses of Parliament, it aimed to reduce accidents between horse-drawn carriages and pedestrians.
Despite its promise, the gas-lit semaphore signals were removed after a year due to a gas leak-caused explosion.
The concept, however, paved the way for modern electric traffic lights introduced decades later.
This pioneering experiment marked a significant moment in urban transport management.
1868
traffic lights
Palace of Westminster
railway signals
semaphore
gas lamps
1968day.year
Douglas Engelbart gave what became known as "The Mother of All Demos", publicly debuting the computer mouse, hypertext, and the bit-mapped graphical user interface using the oN-Line System (NLS).
Douglas Engelbart presents the 'Mother of All Demos', introducing the computer mouse, hypertext, and graphical user interface.
On December 9, 1968, at the Fall Joint Computer Conference in San Francisco, Douglas Engelbart unveils revolutionary computing concepts.
His 90-minute demonstration showcases real-time text editing, hypertext linking, and the first computer mouse.
Using the oN-Line System (NLS), Engelbart navigates windows and displays a proto-graphical user interface.
The demo also introduces collaborative tools like screen sharing and video conferencing.
It lays the groundwork for modern personal computing, influencing companies like Apple and Microsoft.
Often called 'the Mother of All Demos', it marks a turning point in human-computer interaction.
1968
Douglas Engelbart
The Mother of All Demos
computer mouse
hypertext
graphical user interface
oN-Line System (NLS)
1979day.year
The eradication of the smallpox virus is certified, making smallpox the first of only two diseases that have been driven to extinction (with rinderpest in 2011 being the other).
The WHO officially certified the global eradication of smallpox, marking a historic victory in public health.
On December 9, 1979, the World Health Organization declared smallpox eradicated worldwide.
Smallpox became the first human disease to be eliminated through a coordinated global vaccination campaign.
The last natural case was reported in 1977 in Somalia after intensified surveillance and ring vaccination.
Over 50 million health workers participated in the effort, spanning dozens of countries.
Strategic containment and rapid response teams were crucial to interrupting transmission.
This achievement demonstrated the power of international collaboration in disease control.
Smallpox remains one of only two diseases eradicated, alongside rinderpest in 2011.
1979
smallpox
virus
rinderpest
2006day.year
Space Shuttle program: Space Shuttle Discovery is launched on STS-116 carrying the P5 truss segment of the International Space Station.
Space Shuttle Discovery launched on STS-116, delivering the P5 truss segment to expand the International Space Station.
On December 9, 2006, Space Shuttle Discovery lifted off on mission STS-116 from Kennedy Space Center.
Its primary goal was to install the P5 truss segment on the ISS's starboard side.
The P5 segment served as a spacer, enabling extension of the station's solar arrays.
Astronauts performed multiple spacewalks to attach the truss and reroute power cables.
An unexpected thermal blanket issue required an unplanned EVA for repairs.
The mission validated critical assembly procedures for future ISS construction.
Discovery safely returned to Earth on December 22, solidifying further station expansion efforts.
2006
Space Shuttle program
Space Shuttle Discovery
STS-116
P5 truss
International Space Station