Why Edwin Armstrong developed FM radio

How radio works

Antennae tune a radio to a particular frequency (determined by the listener on their radio's dial) while tuning out all the other stations being broadcast. AM, short for amplitude modulation, and FM, short for frequency modulation, decode audio signals differently, leading to differences in sound quality and the distance a station can travel.

How underground radio revitalized rock 'n' roll

Early FM was a wasteland and quickly became the domain of amateurs and risk-takers, including many stations and DJs who played music that flew in the face of mainstream trends. This history of the band's scrappy beginnings unpacks how it realigned the rock charts.

Before the invention of transistors, vacuum tubes made radio possible

Discovered by Thomas Edison, vacuum tubes allow electrical currents to travel through empty space. Later modified into a diode—keeping current flowing in only one direction—vacuum tubes allowed electronics to turn alternating current into direct current.

Franklin D. Roosevelt used radio to connect directly with Americans through his 'Fireside Chats'

Beginning in 1933, FDR harnessed the new medium of radio to explain policies and reassure the public during the Great Depression and World War II. His conversational fireside chats revolutionized presidential communication.

The accidental birth of radio astronomy and the benefits of a moon-based telescope

Detecting radio waves from distant celestial objects is complicated by noise from solar wind, which the nighttime side of the moon is shielded from. If lunar temperature extremes can be overcome, the environment may serve as an optimal future home for radio astronomy, a field that began in 1928 when a 30-meter-long directional antenna, mostly out of brass and wood, picked up signals from the Sagittarius constellation.

A history of the radio jingle

As the radio became a fixture in American households, advertisers recognized the airwaves' commercial potential. Inspired by 19th-century commercially minded poems, the radio jingle was born in 1926 with the ditty "Have You Tried Wheaties?" This guide from the University of Maryland walks you through the evolution of the form, with recordings of its earliest earworms.

The disputed inventor of the radio

Guglielmo Marconi was awarded the 1909 Nobel Prize in physics for inventing the wireless telegraph, which used radio waves to transmit Morse code. Nikola Tesla, however, was experimenting with radio waves in the 1890s, though much of his work was destroyed in a 1895 fire.

Thomas Edison publicly executed animals with AC to convince the public of its dangers

J.P. Morgan first backed Thomas Edison's direct current system, seeing electricity's potential to usurp John D. Rockefeller's kerosene empire. Despite the investments and smear campaign against alternating current, alternating current ultimately won public support after lighting the 1893 World's Fair, after which Morgan would fund Tesla's wireless transmission tower.

A professor explains how podcasts built on radio's strengths

When podcasts were first produced in the early 2000s, they were often recordings of radio shows aimed at listeners who wanted to listen outside of the broadcast windows. Siobhan McHugh, an associate professor of journalism at Australia's University of Wollongong, argues that the form is built on radio's intimacy, amplifying the connection listeners feel with their favorite hosts.

Ed Sullivan launched Beatlemania in America

By 1964, The Beatles were relative unknowns in the US, due to Capitol's lukewarm support. That changed when they were booked on The Ed Sullivan Show, a popular program that hosted Elvis Presley's breakout performance. The Beatles' appearance introduced them to an American audience.

IFA 1931 hosted the first public TV demonstration

In 1931, Manfred von Ardenne presented his cathode ray tube television to the public for the first time, marking the first public demonstration of fully electronic TV. This article examines his breakthrough and the evolution of television technology since.

The anechoic chamber at Bell Labs absorbs 99.999% of created sound

The space nearly eliminates sound wave reflection, allowing visitors to become aware of noises created by their own bodies, including their heartbeat and skeletal conduction. Experiments inside have contributed to the development of digital audio and phone touch tones.

In 1938, 1.7 million people were fooled into believing a Martian invasion was underway because of a radio play

Orson Welles' realistic radio dramatization of a Martian invasion of Earth, called "The War of the Worlds," caused quite a stir with audiences. The broadcast resulted in panic, with some people in the area where the story took place attempting to flee. It also helped Welles secure a contract with a Hollywood studio, leading to the creation of "Citizen Kane."

Pierre Curie's knowledge of electromagnetism helped decipher radioactivity

Alongside his brother, he studied electric fields in crystals and the magnetic properties of substances, which required the construction of delicate electrometers. He would use this apparatus with Marie Curie to measure radioactive emissions and the presence of undiscovered radioactive elements.

Billie Holiday's distinctive vocal technique was aided by new microphone technology

Unlike many of her contemporaries, Holiday's voice was more reserved and seductive. In the past, that wouldn't have been practical—earlier microphones required singers to belt in order to be heard throughout a club or theater. However, technological breakthroughs in the 1930s produced more sophisticated and sensitive microphones, enabling a singer like Holiday to experiment with vocal dynamics.

Jazz legend Louis Armstrong was once the honorary king of the Zulu krewe

The historically Black krewe invited Armstrong to lead their parade in 1949. The invitation fulfilled a lifelong dream for the musician, who grew up in New Orleans. "After that," he told Time magazine in advance of the parade, "I'll be ready to die."

Abbey Road Studios invented stereo recording (and was the site of most of the Beatles' recordings)

Built around 1830 and bought by the Gramophone Company in 1929, the St. John's Wood property became the world's first purpose-built recording studio. Its legacy spans stereo sound's invention, the Beatles' entire catalog, and blockbuster film scores from Star Wars to The Lord of the Rings.

The Wrights’ patent battles delayed the development of aviation technology in the US

By the time World War I began in 1914, the US was lagging behind European powers in aviation. This stemmed primarily from wars over patents between the Wrights and competitor Glenn Curtiss. The pair argued their 1906 patent covered all mechanisms enabling lateral flight.

Carlin's 'Seven Words' led to a landmark Supreme Court ruling

The original recording of Carlin's bit aired on a New York radio station in 1973, leading to an FCC complaint. The case went up to the Supreme Court, which ruled that the FCC had the right to penalize broadcasters that aired obscene content during the daytime.

Many of Wright's buildings used radiant heating

Frank Lloyd Wright’s buildings weren’t just radical because of how they looked, but many of them also incorporated stunning technological innovations. Radiant heating is one of Wright’s most popular heating systems, offering the comfort of walking on warm floors on a cold day.

The history of many kitchen appliances involves unexpected discoveries and applications, including wartime radar turned hamster defroster and replacing an 'ice king' with heat-stealing boxes.

Oxford scientists turned Fleming’s mold discovery into medicine

In 1939, a team at Oxford—including Howard Florey, Ernst Chain, and Norman Heatley—revived Fleming’s forgotten discovery. Using makeshift equipment like bedpans and milk churns, they purified enough penicillin to prove it could treat deadly infections.

Robert Oppenheimer became the face of the Manhattan Project and the atomic bomb

This feature explores Oppenheimer’s early life, the traits that made him central to the development of the atomic bomb, and how his later years were marked by tension between pride in his work and opposition to weapons of mass destruction.

FLOW-MATIC was the first programming language resembling the English language

As part of the team working on UNIVAC—the first commercially produced electronic digital computer in the US—Grace Hopper helped develop the system that enabled nonprogrammers and businesspeople without a strong mathematics background to use the machine effectively, thereby enhancing the computer's commercial viability.

Walter Camp revolutionized American Football

When Walter Camp was introduced to the game of football in the late 1800s, the rules weren’t set, the field wasn’t uniform, and the game was brutal. Camp joined early rules committees and was instrumental in shaping the modern game. Read this deep dive into Camp’s early life and influences, and find out how he established the line of scrimmage and the series of downs.

Fluxgate magnetometers detect magnetic fields using electromagnets

Instead of a compass needle's movement indicating a magnetic field, an alternating current produces an oscillating magnetic field in a metal bar. An external magnetic field creates an imbalance in the oscillations, which can be measured quantitatively.

At the beginning of the 20th century, a group of young men ate standard American food—replete with food additives like borax and formaldehyde—as part of government research to better understand food safety.

Watch a 1934 short film starring jazz legend Cab Calloway, a major figure in the Harlem Renaissance's music scene

The Beatles' US label rejected the band's first two singles, 'Please Please Me' and 'From Me to You,' with one executive calling the band 'dead in the water.'

Long before Major League Baseball began allowing instant replay for balls and strikes, an umpire reluctantly used the technology to determine whether a hit was a home run, a move that inadvertently ushered in a new era for the sport.

70 years ago today, city officials in Santa Cruz, California, banned rock 'n' roll to protect its youth from corruption after witnessing a 'provocative' concert the night before.

English mathematician Ada Lovelace wrote the first computer algorithm a century before computers existed and hypothesized that computing devices would one day be able to compose music—foreseeing the generative AI systems of today.

Fish populations in the Great Barrier Reef have increased after installing waterproof speakers on the ocean floor that played recordings of sounds from healthy coral reefs.

While atoms are normally made of protons, neutrons, and electrons, exotic ones have been built with antimatter—alternate versions of normal matter that live for fractions of a second and are about a billion times as rare.

A small portion of The Winstons' 'Amen, Brother,' an obscure '60s gospel record, is the basis for thousands of hip-hop tracks, making it one of the most sampled records ever that's informally known as 'the Amen break.'

Stars appear to twinkle because turbulence in the motion of molecules in Earth's atmosphere causes light to bend and wiggle rapidly on its way to the surface—a phenomenon called scintillation.

How Amazon operates a 'flywheel' business model, a self-reinforcing cycle that drives continuous growth

The concept of phantom limbs, the perception that amputated limbs are still present, dates back to a French military surgeon in the 16th century.

Sony set the standard for cylinder-shaped batteries when it repurposed manufacturing equipment used to make rolls of magnetic recording tape.

20,000 letters to the advice columnist 'Dear Abby' provide insight into prevailing sex, religion, and LGBTQ fears, anxieties, and concerns from the 1950s onward.

Legendary architect Frank Lloyd Wright designed the SC Johnson headquarters in Wisconsin, aiming to make a cathedral-like workplace

Warren Buffett's former professor Benjamin Graham is known as the 'father of value investing,' a strategy in which investors seek to buy stocks trading below their intrinsic worth.

While the first exchange-traded fund (a 'basket' of different assets that can be bought and sold on a stock exchange) in the US only launched in 1993, the global ETF market has grown to more than $10T in the short time since.

In 1939, baseball star Lou Gehrig delivered his inspirational 'Luckiest Man' speech after retiring due to the health condition that now bears his name.

Double world record holder Hunter Ewen helped conquer his fear of balloons, called globophobia, by training to win Guinness World Record titles for balloon inflation.

Trace how the Bill of Rights, inspired by centuries of political theory, took shape between 1774 and 1789.

Pure water does not conduct electricity because this flow of energy requires the movement of charged particles, and water is a neutral molecule.

Sunflowers have long been a symbol of nuclear disarmament because they can extract large amounts of radioactive cesium from soil.

Apollo astronauts left items in the moon's 'toss zone,' including golf balls, family photos, and bags of human waste, to make room for lunar rocks.

The most expensive ad of all time was for Chanel No. 5 perfume and cost roughly $33M to produce in 2004—about $57M in today's dollars.