- What signal did Marconi hear on Signal Hill, and how far had it traveled?
- Why did scientists initially doubt that a radio signal could travel across the curve of the Earth?
- What atmospheric layer turned out to explain how Marconi's signal reached Newfoundland, and why wasn't it understood at the time?
Radio and Broadcasting History
The invention and spread of radio and television broadcasting.
- How did Henri Becquerel discover radioactivity while trying to test something else entirely?
- What did ships' radio operators normally expect to hear over wireless before Fessenden's Christmas Eve broadcast?
- What did Reginald Fessenden actually broadcast on Christmas Eve 1906?
- How does amplitude modulation differ from simply switching a carrier wave on and off?
- Where was Fessenden's transmitting station located?
- What could Fleming's two-electrode vacuum tube do, and what could it not do?
- What did Lee de Forest add to the vacuum tube to create the Audion, and how did it work?
- Why was the ability to amplify a signal such a significant advance over merely detecting one?
- How long did the triode remain the dominant amplification technology before being replaced?
- How did Lippmann's photographic plates record colour without using any dyes or filters?
- Why did Lippmann's interference-based colour process lose out to dye-based photography despite producing more accurate colour?
- What did Ferdinand Braun's coupled-circuit transmitter contribute to radio that Marconi's own equipment lacked?
- Why was splitting the prize between Marconi and Braun considered diplomatically awkward?
- How did Marconi's transatlantic wireless signal of 1901 depend on innovations he didn't personally develop?
- Why did lighthouses before 1912 require a human keeper to operate them every dusk and dawn?
- What did the spotted patterns on Friedrich and Knipping's photographic plates reveal about crystal structure?
- How did the ionosphere's behavior at night versus day complicate early long-distance radio transmission?
- How did the 1920 transatlantic radio test lay groundwork for commercial broadcasting?
- What kind of programming did KDKA in Pittsburgh broadcast when it launched in November 1920?
- Why did broadcasters and receiver manufacturers need each other for radio to become a mass medium?
- How was radio different for ordinary households in 1920 compared to its first two decades of Morse-code operators and amateur enthusiasts?
- What household materials did John Logie Baird use to build his first television apparatus?
- What was the first image Baird successfully transmitted, and how clear was it?
- What happened after Baird's 1924 transmission that led to a public demonstration and a BBC contract?
- What did Jenkins's 1925 radiovision demonstration actually transmit, and over what distance?
- Why did Jenkins's rotating disk system produce silhouettes rather than clear images?
- Why didn't Jenkins receive lasting credit for inventing television despite this early demonstration?
- Who or what was Stooky Bill, and why was it Baird's first subject for greyscale television?
- What were the resolution and frame rate of Baird's October 1925 television demonstration?
- Who became the first person to appear live on television, and how much was he paid?
- How did a precise theory of electrons boiling off a hot filament make vacuum tubes possible for early radio and television?
- How did Appleton use interference between a direct and a reflected radio wave to measure the height of the ionosphere?
- Why does the F-layer of the atmosphere allow long-distance shortwave radio to skip around the curve of the Earth?
- What would global radio communication have required without a reflecting layer in the upper atmosphere?
- What information does ordinary photography discard that holography manages to preserve?
- How did photographic emulsions work as a particle detector?
- What other scientific fields ended up using emulsion-based particle tracking?
- Why did Korolev's team design Sputnik 1 to broadcast a simple radio beep rather than carry scientific instruments?
- What later innovation in blue LEDs made white LED lighting possible?
- What were Penzias and Wilson actually trying to do with their horn antenna when they found the mysterious hiss?
- How did Wozniak's colour graphics circuit exploit an artifact in the NTSC television standard to avoid dedicated hardware costs?
- What did the AutoVision device actually do inside a moving car?
- Why did the Ig Nobel committee treat AutoVision's working engineering as the problem rather than the achievement?
- How does lighting condition change the number of exposures needed to avoid a blinking subject?
- Why does combining red, green, and blue LEDs into white light matter for global energy use?