Science on This Day: December 16 | The Transistor, Arthur C. Clarke and the Science of Measurement
Science on December 16 offers three different ways to explore how scientific ideas become part of everyday life. In 1947, John Bardeen and Walter Brattain achieved a breakthrough that helped launch the age of modern electronics. In 1917, science-fiction writer Arthur C. Clarke was born, later describing how satellites could transform global communication. And in 1801, George Biddell Airy was born, beginning a career that connected astronomy, optics, precise measurement and investigations into the structure of Earth.
These stories are useful for middle and high school science because they show that scientific progress is not just about discovering new facts. It also depends on understanding materials, developing mathematical models, designing instruments and finding ways to test ideas against evidence.
December 16, 1947: The point-contact transistor changes electronics
Imagine trying to build a computer using components that are bulky, fragile and generate considerable heat. That was one of the challenges facing electronics engineers before the development of practical transistors. Vacuum tubes could amplify electrical signals, but they had limitations in size, power consumption and reliability.
At Bell Laboratories in the United States, physicists John Bardeen and Walter Brattain were investigating how electricity behaved at the boundary between a metal and a semiconductor. On December 16, 1947, their experiments produced the first successful point-contact transistor action. The device used two closely spaced gold contacts pressed against a small piece of germanium, a semiconductor.
The key achievement was amplification. A small change in the electrical signal at one contact could produce a much larger change in the signal flowing through the device. This made it possible to control an electrical signal without relying on a heated vacuum tube.
The first transistor was not a miniature version of the processors found in today's computers. It was a delicate experimental device, and scientists still needed to improve its design and understand how it worked. The research group included William Shockley, who went on to develop the junction transistor, a more practical design. Bardeen, Brattain and Shockley shared the 1956 Nobel Prize in Physics for their work on semiconductors and the transistor effect.
Transistors eventually became fundamental components of radios, computers, smartphones, medical equipment and countless other technologies. Modern processors contain enormous numbers of tiny transistors that act as electronic switches, allowing digital circuits to represent and process information.
Classroom connection: This event is a useful starting point for teaching conductors, insulators and semiconductors. Students can investigate how materials differ in their ability to conduct electricity, then consider why controlling an electrical signal is useful. A discussion could ask students to identify the devices they use every day that depend on transistors, from phones and game consoles to solar-powered equipment.
For a related activity, explore the plasma physics article and research project template. Although plasma and semiconductors are different states or behaviours of matter, both provide opportunities to investigate how the properties of materials influence their technological uses.
December 16, 1917: Arthur C. Clarke imagines communication through satellites
Long before satellite television, global satellite phone networks and live broadcasts from distant parts of the world, Arthur C. Clarke was born in Minehead, England. Clarke became well known as a science-fiction writer, but he also had a strong interest in the scientific and engineering principles behind space exploration.
In October 1945, Clarke published an article in Wireless World titled “Extra-Terrestrial Relays: Can Rocket Stations Give World-Wide Radio Coverage?” He described how satellites in an orbit matching Earth's rotation could be used to relay radio and television signals across enormous distances.
A satellite in a circular geostationary orbit travels approximately 35,786 kilometres above Earth's equator. At this altitude, it takes about one day to orbit Earth, matching Earth's rotation relative to the stars closely enough that it appears to remain above approximately the same point on the equator. This makes it particularly useful for communication: ground antennas can point towards a satellite without needing to track it constantly across the sky.
Clarke proposed that three appropriately spaced satellites could provide extensive global coverage. His article did not mean that the technology already existed. Launching satellites, supplying them with power, transmitting signals and building reliable ground equipment all presented major engineering challenges. The first artificial satellite, Sputnik 1, was not launched until 1957, and practical communications satellites followed later.
Clarke also did not invent the underlying idea of a geostationary orbit from nothing. Earlier thinkers had discussed orbits with matching periods. His important contribution was to clearly develop and publicise a practical application of such orbits for worldwide communication.
Today, satellites help provide television broadcasts, telephone connections, internet access, weather information and communication links for ships and aircraft. Their capabilities also depend on other technologies, including solar panels, antennas, radio transmitters and computer systems.
Classroom connection: Clarke's story works well as a lesson about the relationship between imagination and engineering. Ask students to distinguish between proposing an idea, demonstrating that it is physically possible and developing a reliable technology that people can use. They could sketch a three-satellite system, explain why the satellites need to be spaced around Earth and identify locations that might still face communication challenges.
For a space-themed follow-up, my free Jupiter's Moons infographic, slides, podcast and quiz set provides another way to explore how spacecraft and astronomical observations expand our understanding of the Solar System. The space exploration reading comprehension activity offers a further option for students to investigate the science and technology behind exploring space.
December 16, 1801: George Biddell Airy connects astronomy, optics and Earth science
George Biddell Airy was born in Alnwick, England, in 1801. He became a mathematician and astronomer and served as Britain's Astronomer Royal from 1835 to 1881. His career illustrates how careful measurement can connect different areas of science, from observing stars to investigating the density of our planet.
Airy helped improve the instruments and methods used at the Royal Observatory, Greenwich, where accurate measurements of star positions were essential for astronomy and navigation. The Airy Transit Circle, designed under his direction, became particularly important. In 1884, the telescope's reference line was adopted as the basis for the international prime meridian, the reference longitude of zero degrees. This helped establish a common framework for mapping locations around Earth and coordinating time.
Airy's work also connects with optics. The Airy disk describes the central bright spot and surrounding diffraction pattern produced when light from a point source passes through a circular aperture, such as a telescope opening. Because light behaves as a wave, it does not form a perfectly sharp point image. Instead, diffraction spreads the light into a pattern.
This places a physical limit on how clearly a telescope can distinguish two closely spaced objects, depending on factors including the aperture size and the wavelength of light.
Airy's investigations extended below Earth's surface as well. In experiments at the Harton Colliery in the 1850s, pendulums were compared at different depths in a mine. The measurements helped him estimate Earth's mean density. The reasoning involved gravity: the gravitational attraction measured by a pendulum changes with location, and measurements inside a mine can provide evidence about the distribution of mass within Earth.
The experiment was not simply a matter of weighing the planet. It required carefully comparing measurements, accounting for the local geology and applying mathematical reasoning to infer a property of the whole Earth from observations made in a limited location. This is a good example of how scientists use indirect evidence to estimate quantities that cannot be measured directly.
Classroom connection: Airy's work offers several possible lesson starters. In physics, students can investigate how aperture size affects the resolution of an optical system. In astronomy, they can consider why larger telescopes can reveal finer detail. In geophysics, they can explore how scientists infer the internal structure of Earth using measurements of gravity, seismic waves and other evidence.
Airy's career also provides a chance to discuss the importance of measurement uncertainty. How precise does a measurement need to be before it can support a useful scientific conclusion? What assumptions must be made when using a local measurement to infer something about an entire planet?
Make science history part of your classroom routine
These three December 16 events connect physics, astronomy, engineering and Earth science, but they also share a broader theme: scientific knowledge grows when people turn observations and ideas into testable explanations and useful technologies.
A short science-history warm-up can introduce a new topic, provide a discussion prompt or help students connect a familiar technology with the science behind it. You could use the transistor to introduce semiconductors, Clarke's satellite proposal to begin a unit on orbits and communication, or Airy's work to explore diffraction and the measurement of Earth's properties.
My December Science on This Day resource set makes it easier to use these connections throughout the month. It contains 132 STEM events across December, with an interactive HTML version for filtering and selecting events, editable slides with classroom discussion questions, a spreadsheet and a printable PDF. You can use a single event as a quick starter or choose a relevant date to reinforce a topic you are already teaching.
What else happened in science during December?
There are plenty more opportunities to connect science history with the curriculum over the coming days. On December 17, the Wright brothers' first powered flight in 1903 provides a starting point for discussing forces, lift, propulsion and engineering design. The date is also associated with important developments in chemistry and nuclear science.
On December 18, the birth of physicist J. J. Thomson in 1856 offers a link to the discovery of the electron and the development of atomic models. Students can examine how new evidence changed scientists' understanding of matter.
On December 21, Apollo 8 launched in 1968 on the first crewed mission to orbit the Moon. The mission provides opportunities to discuss orbital motion, spacecraft navigation and the challenges of sending people beyond low Earth orbit.
Later in the month, December 24 is associated with the famous Earthrise photograph taken by Apollo 8 astronaut William Anders in 1968, while December 25, 2021, marks the launch of the James Webb Space Telescope. These events can support discussions about observing Earth and the Universe from new perspectives, as well as the engineering involved in building and operating major space missions.
With a mixture of discoveries, inventions, scientific biographies and space milestones, December offers plenty of ways to bring the history of science into everyday lessons. Selecting one event at a time can help students see science not as a collection of finished facts, but as a continuing process of asking questions, testing ideas and building on earlier work.
Thanks for reading
Cheers and stay curious
Oliver - The Teaching Astrophysicist
