Snowflakes appear on college entrance examination papers! Let’s review: "Science Experiments Inspired by Snow"

An article about the "winter elves" snowflakes written by popular science writer Yin Chuanhong appeared on the college entrance examination paper. As he reviewed his feelings about the creation, let's learn from the scientific exploration spirit of our ancestors >>

Written by Yin Chuanhong (Vice Chairman of the China Science Writers Association)

New Media Editor/Li Yunfeng

The original text of "Science Experiments Inspired by Snow" is as follows:

Before science developed to the point where humans could recognize and understand snow, this "winter spirit" always seemed very magical. In order to uncover its mystery, our ancestors not only let their imaginations run wild, but also explored it through practical actions.

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Freezing experiment

One day at the end of March 1626, Francis Bacon, a British philosopher and essayist who had just celebrated his 65th birthday, rode a four-wheeled carriage out of London and headed for Highgate in the northern suburbs. The air was damp and cool along the way, and snow that had not yet melted could be seen from time to time.

▲Francis Bacon (Photo source: "Knowledge is Power")

Although he was feeling unwell, Bacon, who had been thinking all the time, suddenly had an idea: Would snow have the same antiseptic effect on meat as salt? When the car reached the foot of Highgate Hill, Bacon decided to do a freezing antiseptic experiment immediately. He got out of the car excitedly, bought a chicken from a family, asked the hostess to help remove the internal organs, and then stuffed handfuls of snow into the chicken cavity.

After all the preparations, Bacon suddenly felt cold all over. That night he had a high fever. At first he didn't care, and wrote to a friend saying that he had used snow to freeze hens, and compared his actions with the feat of the ancient Roman writer Pliny the Elder: "I have a similar fate to Pliny the Elder, who lost his life because of his attempt to conduct an experiment on Mount Vesuvius."

Unfortunately, his words came true! A few days later, on April 9, 1626, Bacon died of suffocation due to a relapse of bronchitis.

Today, people remember Bacon's name mainly because he proposed a series of philosophical theories of materialistic empiricism, formulated a systematic inductive logic, and especially summarized the empirical method of scientific experiments for the first time - induction, which played a guiding role in the development of modern science. His famous saying "knowledge is power" is even more well-known.

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Interesting snowflake structure

For thousands of years, people have not only admired the elegance, purity and beauty of snow, but also noticed its peculiar shape. As early as the Western Han Dynasty, more than 100 years before Christ, a poet named Han Ying pointed out in the book "Han Shi Waizhuan": "All flowers of plants and trees have five petals, but snowflakes have six petals." Many years later, European works mentioned that the basic shape of snowflakes is hexagonal. Swedish Archbishop Olaf Magnus (1490-1557) is considered the first European to record this. He described snow crystals and drew pictures in a natural history book published in 1555.

In the early 17th century, snowflakes also attracted the attention of Johannes Kepler (1571-1630), a German astronomer and founder of the laws of planetary motion. In a pamphlet called "Hexagonal Snowflakes" written in 1611, Kepler said that when he was crossing a bridge in Prague, he noticed a snowflake that fell on his clothes and pondered its incredible geometry. He thought it couldn't be a coincidence: "This cause cannot be found in the material, because water vapor is invisible and flowing, and the cause can only exist in some mechanism." Furthermore, he speculated that this mechanism might be the orderly accumulation process of ice "balls", which represent the smallest natural unit of liquids like water.

About 20 years later, French mathematician and philosopher René Descartes (1596-1650) was also fascinated by the beauty of snowflakes. He expressed his admiration in his observation notes: "Perfect hexagons! The sides are so straight and the angles are so precise that clumsy humans simply cannot do it... I absolutely cannot imagine how these perfectly symmetrical hexagonal elves can be born leisurely in the free air and manic wind."

▲The shape of ice crystals composed of water molecules is determined by surface tension. The protrusions of the ice crystals extend in six directions, making most (not all) snowflakes hexagonal (Image source: "Knowledge is Power")

After the invention of the microscope, snowflakes became a popular subject for observation. The famous Dutch microscopist Antonie van Leeuwenhoek (1632-1723) made detailed observations of snowflakes. Then, in his book Microscopy published in 1665, British physicist Robert Hooke (1635-1703) showed the pictures of snowflakes he drew with the help of a microscope and explained the crystal structure of snowflakes. This is regarded as the first time that humans have specifically recorded the morphology of snowflakes.

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Contribution of Snowmaniac

▲Wilson Bentley

One day in 1885, in the town of Jericho in northern Fremont, a farmer named Wilson Bentley (1865-1931) took the first set of snowflake photos with the help of an old microscope and a camera. He wrote: "Under the microscope, I found that the snowflakes were so beautiful, it was simply a miracle. Each snowflake crystal was a masterpiece of art, and no two snowflakes were exactly the same. When a snowflake melted, the pattern disappeared forever. That kind of beauty just disappeared without leaving any trace."

▲Photos of snowflakes taken by Wilson Bentley

Bentley made a wish to use his camera to preserve the beautiful snowflakes forever. Over the decades, he took a total of 5,381 photos of snowflakes. Once, when he was categorizing the snowflake photos, he used an elegant title such as "The Smile of a Pretty Girl". The topic that he caused people to think about - no two snowflakes are exactly the same, and the astonishing number of snowflake photos he took made him famous in the 19th century, although some people regarded him as a "mad farmer". On December 23, 1931, a blizzard raged in Bentley's hometown. Suffering from pneumonia, he still insisted on walking out to take pictures of snowflakes, but eventually he collapsed in the wilderness where snowflakes were flying due to exhaustion.

Today, scientists have a good understanding of how water freezes and how small ice crystals form snowflakes. Science historians believe that the impetus for these discoveries is largely due to the wonderful snowflake pictures taken by "snow maniac" Bentley.

(Originally published in Knowledge is Power, Issue 1, 2016, Pages 26-27)

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