Science on This Day: November 16 | Early Electronics, UNESCO and the Arecibo Message
November 16 brings together three very different stories from science and technology history. In 1904, John Ambrose Fleming patented an electronic component that helped shape early radio technology. In 1945, representatives signed the constitution of UNESCO, establishing an organisation that would support international cooperation in science and education. In 1974, astronomers transmitted a carefully encoded radio message towards a distant star cluster, raising questions about communication, mathematics and the search for life beyond Earth.
These events provide useful connections between physics, computing, astronomy and science in society. They also show that scientific progress depends on more than individual discoveries. It can require new technology, shared knowledge and creative ways to communicate information.
For middle and high school teachers, November 16 offers several opportunities to introduce a topic, encourage students to ask questions or connect a current unit to a real historical event.
November 16: John Ambrose Fleming and the development of electronics
On 16 November 1904, British electrical engineer John Ambrose Fleming patented the thermionic valve, also known as a vacuum-tube diode. This device became an important building block in early electronics, helping engineers control the flow of electric current and develop equipment for detecting and processing electrical signals.
A thermionic valve works by using heated electrons inside an evacuated tube. In Fleming's diode, a heated element releases electrons, which can travel towards a positively charged electrode. The arrangement allows current to flow much more readily in one direction than the other. This behaviour is known as rectification.
Why was this useful? Electrical signals in early radio systems could be weak and difficult to detect. A component that could separate or rectify signals helped make radio reception more practical. Fleming's work built on earlier discoveries about the behaviour of electrons and the effects of heating materials, turning scientific understanding into a useful engineering application.
Vacuum tubes later became important in radio transmitters and receivers, early computers, amplifiers and other electronic equipment. They were eventually replaced in most applications by semiconductor devices, particularly transistors, which are smaller, generally more energy-efficient and easier to integrate into complex circuits. Nevertheless, the thermionic valve was an important step towards the electronics students use today.
This history offers a useful reminder that modern technology develops through a series of improvements. The smartphone, computer or radio is not the result of a single invention. It depends on generations of research into electricity, materials, electronic components and the systems that connect them.
Classroom connection: In physics, students can explore the difference between alternating and direct current, investigate how diodes control current flow, or trace the development of electronic components from vacuum tubes to transistors and integrated circuits. A discussion question for older students is: why might engineers replace one technology with another, even when the original technology still works?
November 16: UNESCO and the role of science in society
On 16 November 1945, representatives signed the constitution of the United Nations Educational, Scientific and Cultural Organization, better known as UNESCO. The organisation was established in the aftermath of the Second World War, with the aim of promoting cooperation in education, science, culture and communication. Its constitution came into force on 4 November 1946.
Unlike a laboratory discovery or a new piece of equipment, UNESCO's creation represents an important development in how people organise and share knowledge. Scientific research often depends on collaboration between researchers, institutions and countries. Scientists may need to share observations, compare data, agree on measurement standards or work together on questions that extend beyond national borders.
International cooperation is particularly important when dealing with challenges such as climate change, biodiversity loss, infectious diseases, ocean pollution and access to education. These problems involve interconnected systems and often require evidence gathered in many locations. Collaboration can help researchers build a more complete picture than any one group could develop alone.
UNESCO also highlights the relationship between science and society. Scientific knowledge can inform decisions, but it does not automatically determine which decisions people should make. Communities and governments must also consider evidence, resources, ethics, cultural priorities and the likely consequences of different choices.
For students, this creates an opportunity to think about what responsible science looks like. How should research findings be communicated to the public? Why is access to scientific education important? How can scientists from different countries work together when they have different resources or priorities?
Classroom connection: In biology or Earth science, students could investigate a global issue such as ocean pollution or biodiversity loss and identify the types of data researchers would need to share internationally. Ask students to distinguish between a scientific finding, a policy decision and a personal or community value. This can help them understand why scientific evidence matters in public decision-making without assuming that every difficult question has a purely scientific answer.
November 16: The Arecibo message and communication beyond Earth
On 16 November 1974, scientists transmitted a radio message from the Arecibo Observatory in Puerto Rico towards the globular cluster M13, approximately 25,000 light-years from Earth. The transmission demonstrated the capabilities of the observatory following an upgrade and became one of the best-known examples of an attempt to communicate information across interstellar distances.
The message contained 1,679 bits of information. A bit is a basic unit of digital information that can take one of two values, commonly represented as 0 or 1. The message was designed as a sequence of binary values that could be arranged into a rectangular pattern, revealing a collection of diagrams and numerical information.
The number 1,679 was chosen because it is the product of two prime numbers, 23 and 73. If a receiver recognised this structure, it could potentially arrange the bits into a grid of 23 columns and 73 rows, or the reverse. The resulting pattern contained information about numbers, elements associated with life, aspects of human biology, the Solar System and the transmitting telescope.
This was not a conversation with extraterrestrial life, and there is no evidence that the message was received by an intelligent civilisation. It was primarily a demonstration of radio astronomy and the ability to encode information for transmission. M13 is so distant that the radio signal would take roughly 25,000 years to arrive, assuming it reaches the cluster, and a reply would require a similar journey back.
The Arecibo message raises a particularly interesting question: how could we communicate with a receiver that does not share our language, culture or assumptions? Scientists chose mathematical patterns and physical information in the hope that some features might be understandable without knowledge of human languages. However, even apparently simple symbols may be interpreted differently without shared context.
This links the event to mathematics, computing, physics and the search for life beyond Earth. It also demonstrates that transmitting a message is not the same as ensuring that someone can interpret it. Communication depends on both the information sent and the knowledge available to the receiver.
Classroom connection: Ask students to design a short message that could be understood by someone who does not speak their language. They might use patterns, numbers, diagrams or repeated sequences. Have groups exchange messages and try to interpret them without explanations. Students can then discuss which features were easy to understand, which were ambiguous and how they might improve their designs. In computing lessons, the activity can lead into binary representation, data encoding and the difference between information and meaning.
Bringing science history into your classroom
The three events from November 16 offer different ways to make science relevant to students. Fleming's thermionic valve connects physics to the development of electronics. UNESCO provides a starting point for discussing the responsibilities and benefits of scientific cooperation. The Arecibo message combines mathematics and computing with questions about communication and life beyond Earth.
A simple approach is to use one event as a five-minute lesson starter. Display the event's date and a short description, then ask students to generate questions, make predictions or identify links to their current topic. Students can investigate one of those questions later in the lesson, turning a historical event into a starting point for scientific inquiry.
For a wider selection of classroom-ready ideas, my November Science on This Day resource set includes 109 STEM stories across the 30 days of November. It comes in several formats, including an interactive HTML version with filters, editable Google Slides with discussion questions, a filterable spreadsheet and a PDF version. You can use individual stories for retrieval practice, lesson starters, short research tasks or classroom discussions.
You can also browse The Teaching Astrophysicist's resource collection for additional science activities across astronomy, biology, chemistry, physics, Earth science and other STEM subjects, including free resources.
What else happened in November?
The following days offer further opportunities to connect science history with classroom learning. On November 17, mathematician August Möbius provides an introduction to topology through the surprising properties of the Möbius strip. The same date marks a major Leonid meteor storm in 1966, which can lead into discussions of meteor showers, observation methods and the reliability of scientific measurements.
On November 19, students can explore the launch of the first living creatures into space or investigate developments in spaceflight and astronomy. Later in the month, discoveries involving X-rays, major advances in computing and the history of space exploration provide further opportunities to connect scientific principles with technological change.
The important point is that science history does not need to take up an entire lesson. A short story can help students see why a scientific idea matters, how evidence has changed our understanding or why a technology developed in the first place. By returning to these connections throughout November, teachers can build a classroom routine that encourages curiosity while reinforcing the science students are already learning.
Thanks for reading
Cheers and stay curious
Oliver - The Teaching Astrophysicist
