Science on This Day: December 5 | Quantum Physics, Deadly Smog, and Einstein’s Journey to America
December 5 brings together three stories that show how science connects with the world beyond the laboratory. Werner Heisenberg helped transform our understanding of matter at the smallest scales. The Great Smog of London revealed the serious consequences of air pollution and led to changes in environmental law. Meanwhile, Albert Einstein’s struggle to obtain a US visa offers a reminder that even world-famous scientists are affected by politics and public attitudes.
These events work well as science starters because they invite students to think about very different questions: How much can we know about a particle? How can weather make pollution more dangerous? And what happens when scientific work intersects with political pressure?
1901: Werner Heisenberg is born
Werner Heisenberg was born on December 5, 1901, in Würzburg, Germany. He became one of the leading physicists involved in the development of quantum mechanics, the branch of physics used to describe matter and energy at atomic and subatomic scales. In 1925, when he was only 23, Heisenberg developed a mathematical approach that helped establish modern quantum mechanics. He later became closely associated with the uncertainty principle, which he introduced in 1927.
In everyday life, we often imagine that an object has a definite position and speed, whether or not we know them. Quantum physics challenges that simple picture for tiny particles. The uncertainty principle places a fundamental limit on how precisely certain pairs of properties, such as a particle’s position and momentum, can be specified together. This is not merely a problem with using an imperfect measuring instrument. It is part of how quantum systems behave.
The idea can be difficult to picture because our everyday experience involves much larger objects. A football, for example, can usually be described by its position and motion with great accuracy. Electrons and other subatomic particles behave differently, and quantum mechanics provides a framework for predicting their behaviour. Heisenberg received the 1932 Nobel Prize in Physics for the creation of quantum mechanics, although the award was presented in 1933.
Classroom connection: Ask students what information they would need to describe the motion of a moving object. They might suggest its position, speed and direction. Then introduce the idea that the same intuitive picture does not work perfectly at the quantum scale. Students can research how scientists use mathematical models and experimental evidence to describe particles, even when those descriptions do not match everyday intuition.
For younger students, the key question can simply be: “Are there limits to what we can know about the natural world?” Older students can explore the difference between uncertainty caused by poor equipment and uncertainty that arises from the physics itself. This also provides an opportunity to discuss how scientific models can be reliable and useful without behaving like miniature versions of the familiar world.
1952: The Great Smog of London begins
On December 5, 1952, a severe episode of air pollution began to envelop London. It became known as the Great Smog and lasted until December 9. Cold weather had increased the use of coal for heating, while factories and power stations also released pollution into the air. Weather conditions then trapped much of this pollution close to the ground, creating a thick mixture of fog and smoke.
A key part of the explanation was a temperature inversion. Normally, air near the ground can rise and help pollutants disperse. During an inversion, a layer of warmer air sits above cooler air near the surface, restricting vertical movement. With little wind to clear the air, smoke particles and gases accumulated. The fog made visibility extremely poor, disrupting transport and everyday life, while polluted air caused serious respiratory problems.
The death toll illustrates the severity of the event. Around 4,000 excess deaths were initially attributed to the smog, and later research suggested that the longer-term toll may have reached approximately 12,000. The disaster helped drive public and political pressure for cleaner air. The UK’s Clean Air Act of 1956 introduced measures to reduce smoke pollution, including controls on emissions and provisions for smoke-control areas.
The Great Smog is a useful example of how environmental problems can arise from the interaction of human activity and natural processes. Burning coal released pollutants, but the weather determined how effectively those pollutants dispersed. Neither factor alone tells the whole story.
Classroom connection: Students can investigate the difference between an emission source and the environmental conditions that affect the spread of pollution. Ask them to compare two scenarios: a windy day when pollutants can disperse and a still day with an atmospheric inversion. What might happen to pollution concentrations in each case?
A simple investigation could use a model of air layers with different temperatures, or students could analyse air-quality data and weather maps. They can also discuss the trade-offs involved in energy choices. Coal provided heat and powered industry, but its emissions had health consequences. How can governments balance energy needs, affordability and public health?
The Great Smog also offers a link to chemistry. Students can distinguish between visible particles, such as soot, and gases that may be invisible but harmful. The absence of a visible haze does not necessarily mean that air is clean.
1932: Albert Einstein’s US visa controversy
December 5, 1932, is associated with Albert Einstein’s attempt to obtain a US visa for a planned visit. The date needs a small clarification: historical reports indicate that Einstein was questioned by American consular officials on December 5, and his visa was granted on December 7. The episode is therefore best understood as a story that began on December 5, rather than a visa being granted that day.
Einstein was already internationally renowned for his work in physics, including the theory of relativity, but his public positions also made him a controversial figure. He supported pacifism and spoke out on political and social issues. His visa application became the subject of scrutiny after a US organisation objected to his political beliefs and urged that he be excluded from the country. The resulting delay and questioning attracted press attention.
At the time, Einstein had plans to travel to the United States for scientific work, including work connected with the Mount Wilson Observatory in California and his future association with the Institute for Advanced Study in Princeton. He ultimately left Europe for the United States in December 1932. As the Nazi Party consolidated power in Germany, the situation for Jewish people and political opponents became increasingly dangerous. Einstein did not return to live in Germany, and he settled in the United States, becoming an American citizen in 1940.
This episode is a reminder that science does not happen in isolation. Researchers depend on universities, laboratories, funding, travel and international collaboration. Political decisions can affect who is able to work, where they can live, and whether they can continue their research safely.
Classroom connection: Invite students to discuss why scientists might travel to work with other researchers or use specialised observatories and laboratories. What could happen to scientific progress if researchers were prevented from travelling or sharing their work? Students can also consider the difference between evaluating scientific ideas using evidence and judging a scientist based on political beliefs.
For a history or citizenship connection, ask students to place Einstein’s visa experience in the context of the political climate of the early 1930s. Encourage them to distinguish between the events of December 1932 and the later developments that led Einstein to remain in the United States.
Bring science history into your lessons
These three events make useful starting points for different parts of the curriculum. Heisenberg connects to atomic physics and the nature of scientific models. The Great Smog links chemistry, weather, environmental science and public health. Einstein’s visa story provides a way to discuss the relationship between science, politics and international cooperation.
If you want ready-to-use ways to bring science history into your classroom, the December Science on This Day activity set contains 132 STEM items across all 31 days of December. The set includes an interactive HTML version with date and subject filters, classroom display mode and discussion questions, plus editable slides, a filterable spreadsheet and a printable PDF. You can choose a story that fits your current topic or use one as a short daily warm-up.
You can also explore the Teaching Astrophysicist store for other science teaching resources, including free materials alongside paid activities.
More science history to explore in December
The rest of December offers plenty of opportunities to connect historical events with classroom topics. On December 10, the first Nobel Prizes were awarded in 1901, providing a starting point for discussing how scientific achievements are recognised. December 11 marks Apollo 17’s landing on the Moon in 1972, while December 14 connects to Max Planck’s presentation of quantum theory in 1900 and the Mariner 2 mission’s encounter with Venus in 1962.
On December 17, the Wright brothers’ first powered flight in 1903 can lead into forces, lift and engineering design. The same date is associated with the discovery of nuclear fission in 1938, which offers a very different discussion of scientific evidence and the consequences of discovery. December 21 marks the launch of Apollo 8, the first crewed mission to orbit the Moon, and December 24 is associated with the famous Earthrise photograph taken during that mission.
Finally, December 25 marks the launch of the James Webb Space Telescope in 2021, a modern example of how advances in engineering and observation allow scientists to investigate the universe. Whether you are teaching physics, biology, chemistry or environmental science, science history can help students connect abstract concepts to real people, evidence and decisions that changed our understanding of the world.
Thanks for reading
Cheers and stay curious
Oliver - The Teaching Astrophysicist
