International Day of Light

May 16th is the International Day of Light, celebrating the first fruitful laser trial by physicist Theodore Maiman in 1960. The study of light has led to many advances in technology and improvements to our everyday lives, which is why it is a UNESCO event. From UNESCO's website:

Without light, our planet would be but a cold and barren place. Indeed, where there is light, there is often an abundance of life. Yet light represents even more for humanity. Light goes hand in hand with knowledge; it is a lens through which to see and understand the world.

Our Center for History of Physics has a web exhibit titled Bright Idea: The First Lasers all about how lasers and masers came to exist. Check out the exhibit linked above, as well as this Tweet thread that explains key points from the exhibit in a condensed format below.

(P.S. For even more wonderful web exhibits, check out our Museum Tour post!) 

Note: it may take a few seconds for tweets to load.

— Center for History of Physics (@aip_history) May 8, 2023

It starts with the electromagnetic spectrum. By the early 20th century, scientists understood that light rays could be thought of as electromagnetic waves — similar to radio waves, but with much shorter wavelengths. #LightDay2023

It starts with the electromagnetic spectrum. By the early 20th century, scientists understood that light rays could be thought of as electromagnetic waves — similar to radio waves, but with much shorter wavelengths. #LightDay2023 pic.twitter.com/SZqTbVf7bY

— Center for History of Physics (@aip_history) May 9, 2023

As the Cold War against the Soviet Union began, the US government poured funds into basic and applied research. Industrial and university laboratories proliferated during this time. It was from this fertile soil that the laser would grow. #LightDay2023

As the Cold War against the Soviet Union began, the US government poured funds into basic and applied research. Industrial and university laboratories proliferated during this time. It was from this fertile soil that the laser would grow. #LightDay2023 pic.twitter.com/Kskqofe6tr

— Center for History of Physics (@aip_history) May 9, 2023

Charles Townes of @Columbia University studied molecules in the 1930s and worked on radar as an electronics engineer during the war. @USNavyResearchchallenged him & other physicists to invent a way to make powerful radiation beams at ever shorter wavelengths. #LightDay2023

Charles Townes of @Columbia University studied molecules in the 1930s and worked on radar as an electronics engineer during the war. @USNavyResearch challenged him & other physicists to invent a way to make powerful radiation beams at ever shorter wavelengths. #LightDay2023 pic.twitter.com/XwJe2NCEH4

— Center for History of Physics (@aip_history) May 10, 2023

"I decided, 'Well, we have to do something drastic.'" In this 1987 #OralHistory interview excerpt, physicist Charles Townes recalled the day he invented the maser. #LightDay2023 https://www.aip.org/history-programs/niels-bohr-library/oral-histories/…

"I decided, 'Well, we have to do something drastic.'"

In this 1987 #OralHistory interview excerpt, physicist Charles Townes recalled the day he invented the maser. #LightDay2023

🔗: https://t.co/C3gEkkMmfe pic.twitter.com/vEe7QZ7vYy

— Center for History of Physics (@aip_history) May 10, 2023

Townes predicted and observed a remarkable and useful property for the radiation from the device: it would be at a single frequency, as pure as a note from a tuning fork. This would give the maser, and later the laser, important practical uses.

Townes predicted and observed a remarkable and useful property for the radiation from the device: it would be at a single frequency, as pure as a note from a tuning fork. This would give the maser, and later the laser, important practical uses.

— Center for History of Physics (@aip_history) May 11, 2023

One day in 1957, studying the equations for amplifying radiation, Townes realized that it would be easier to make it happen with shorter waves than with far-infrared waves. He talked it over with his colleague, friend, and brother-in-law Arthur Schawlow. #LightDay2023

One day in 1957, studying the equations for amplifying radiation, Townes realized that it would be easier to make it happen with shorter waves than with far-infrared waves. He talked it over with his colleague, friend, and brother-in-law Arthur Schawlow. #LightDay2023 pic.twitter.com/EiDEDTN69M

— Center for History of Physics (@aip_history) May 11, 2023

Meanwhile, the same idea occurred to Gordon Gould, a grad student @Columbia who'd discussed the problem with Townes. As Gould speculated about the uses of a concentrated beam of light, he realized that he was onto something far beyond the infrared maser. #LightDay2023

Meanwhile, the same idea occurred to Gordon Gould, a grad student @Columbia who'd discussed the problem with Townes. As Gould speculated about the uses of a concentrated beam of light, he realized that he was onto something far beyond the infrared maser. #LightDay2023 pic.twitter.com/rYTrb5QvEF

— Center for History of Physics (@aip_history) May 11, 2023

In his notebook, Gordon Gould confidently named the yet-to-be-invented device a LASER (for Light Amplification by Stimulated Emission of Radiation). In April 1959 he filed patent applications with his employer, the high-tech research firm TRG. #LightDay2023

In his notebook, Gordon Gould confidently named the yet-to-be-invented device a LASER (for Light Amplification by Stimulated Emission of Radiation). In April 1959 he filed patent applications with his employer, the high-tech research firm TRG. #LightDay2023 pic.twitter.com/iy7WxE8akX

— Center for History of Physics (@aip_history) May 12, 2023

This would be the beginning of a litigious patent war between Gould and Townes & Schawlow, who went on to apply for a patent on behalf of Bell Labs nine months later. In 1987 Gould and his backers began to win settlements, ending one of the greatest patent wars in history.

This would be the beginning of a litigious patent war between Gould and Townes & Schawlow, who went on to apply for a patent on behalf of Bell Labs nine months later. In 1987 Gould and his backers began to win settlements, ending one of the greatest patent wars in history.

— Center for History of Physics (@aip_history) May 12, 2023

The historical question of how to assign credit for inventing the laser remains controversial. Here, Ali Javan, Iranian-American physicist and former student of Charles Townes, comments on credit for the discovery of the maser and lasers. #LightDay2023

The historical question of how to assign credit for inventing the laser remains controversial. Here, Ali Javan, Iranian-American physicist and former student of Charles Townes, comments on credit for the discovery of the maser and lasers. #LightDay2023 pic.twitter.com/78QsXokqx8

— Center for History of Physics (@aip_history) May 12, 2023

When Schawlow and Townes published their ideas in 1958, physicists everywhere realized that an "optical maser" could be built. Laboratories at @Columbia, TRG Corp, @Westinghouse_86, @IBMResearch, @HRLLaboratories, and @BellLabseach hoped to be the first to succeed. #LightDay2023

When Schawlow and Townes published their ideas in 1958, physicists everywhere realized that an "optical maser" could be built. Laboratories at @Columbia, TRG Corp, @Westinghouse_86, @IBMResearch, @HRLLaboratories, and @BellLabs each hoped to be the first to succeed. #LightDay2023

— Center for History of Physics (@aip_history) May 15, 2023

On May 16, 1960, @HRLLaboratories' Theodore Maiman created the world's first laser using a synthetic ruby and a helical flash lamp. Back @BellLabs, Ali Javan, Donald Herriott & William Bennett produced a continuous beam of infrared rays — the first gas laser. #LightDay2023

On May 16, 1960, @HRLLaboratories' Theodore Maiman created the world's first laser using a synthetic ruby and a helical flash lamp. Back @BellLabs, Ali Javan, Donald Herriott & William Bennett produced a continuous beam of infrared rays — the first gas laser. #LightDay2023 pic.twitter.com/PCoJY5Zmws

— Center for History of Physics (@aip_history) May 15, 2023

By the end of 1960, three different types of lasers had been demonstrated. In this excerpt from his 1985 #OralHistory interview, Peter Franken described the 1961 @OpticaWorldwide meeting as "Panicville." https://www.aip.org/history-programs/niels-bohr-library/oral-histories/…;

By the end of 1960, three different types of lasers had been demonstrated. In this excerpt from his 1985 #OralHistory interview, Peter Franken described the 1961 @OpticaWorldwide meeting as "Panicville."

🔗: https://t.co/myMVrwAMT9 pic.twitter.com/qMftywENWs

— Center for History of Physics (@aip_history) May 15, 2023

50 years after the first laser, there are few people in modern society who haven't been affected by the invention. Lasers have revolutionized communication, improved commerce, industry & entertainment, and advanced science through research & practical applications. #LightDay2023

50 years after the first laser, there are few people in modern society who haven't been affected by the invention. Lasers have revolutionized communication, improved commerce, industry & entertainment, and advanced science through research & practical applications. #LightDay2023

— Center for History of Physics (@aip_history) May 16, 2023

Laser technology was also famously used to destroy the Death Star in the 1977 space opera film "Star Wars: Episode IV - A New Hope." It has remained a fixture in pop culture and science fiction ever since its discovery. https://history.aip.org/exhibits/laser/#section6 

Laser technology was also famously used to destroy the Death Star in the 1977 space opera film "Star Wars: Episode IV - A New Hope." It has remained a fixture in pop culture and science fiction ever since its discovery. https://t.co/8tqPdq2XD0 pic.twitter.com/puhGuFwASb

— Center for History of Physics (@aip_history) May 16, 2023

Thanks for following along! To learn even more about the history and discovery of lasers, visit our free virtual exhibit "Bright Idea: The First Lasers." #LightDay2023 https://history.aip.org/exhibits/laser/

Thanks for following along! To learn even more about the history and discovery of lasers, visit our free virtual exhibit "Bright Idea: The First Lasers." #LightDay2023 https://t.co/BBIOtx920J pic.twitter.com/ltpTuDu0fd

— Center for History of Physics (@aip_history) May 16, 2023