Ikigai Daily
Menu
DriveScience fact

In 1912 the German scientist Alfred Wegener proposed that the continents were once joined and have slowly drifted apart. He pointed to matching fossils and rocks on opposite sides of oceans and to the way coastlines fit together, but the idea stayed controversial for decades because he could not say what moved them.

History of science

ScienceHistory

The story behind the card

Wegener first set out the idea in a 1912 lecture and expanded it in his 1915 book The Origin of Continents and Oceans. Most geologists rejected it, chiefly because the forces he suggested were far too weak to push whole continents across the ocean floor. He died on a Greenland expedition in 1930. From the 1950s new evidence changed the picture: rocks turned out to preserve a record of Earth's ancient magnetic field (palaeomagnetism), and ocean floors were found to form at mid-ocean ridges and spread apart. Together with worldwide earthquake patterns, these findings led in the 1960s to plate tectonics, the theory that Earth's outer shell is broken into moving plates, which gave continental drift its missing mechanism.

Türkçe oku
Alman bilim insanı Alfred Wegener 1912'de kıtaların bir zamanlar birleşik olduğunu ve yavaşça birbirinden uzaklaştığını öne sürdü. Okyanusların iki yakasındaki benzer fosillere, kayalara ve kıyıların birbirine oturmasına dikkat çekti; ama kıtaları neyin hareket ettirdiğini açıklayamadığından fikri onlarca yıl tartışıldı.

Wegener fikrini ilk kez 1912'de bir konferansta anlattı, 1915'te yayımladığı Kıtaların ve Okyanusların Kökeni adlı kitabında geliştirdi. Jeologların çoğu fikri reddetti; asıl gerekçe, önerdiği kuvvetlerin koca kıtaları okyanus tabanı boyunca sürükleyemeyecek kadar zayıf olmasıydı. Wegener 1930'da bir Grönland seferinde öldü. 1950'lerden itibaren yeni kanıtlar tabloyu değiştirdi: kayaların Dünya'nın geçmişteki manyetik alanının izini sakladığı (paleomanyetizma), okyanus tabanının da okyanus ortası sırtlarında oluşup iki yana açıldığı anlaşıldı. Bu bulgular ve dünya genelindeki deprem örüntüleri 1960'larda levha tektoniği kuramını doğurdu: Dünya'nın dış kabuğu hareket eden levhalardan oluşur. Kıta kayması da böylece eksik kalan açıklamasına kavuştu.

Sources and further reading

Background reading: Alfred Wegener
Get the mobile appAbout our cards

Related cards

These cards share a subject or reading mode with the card above.

StillnessScience

People used fermentation, the work of yeasts and bacteria, to raise bread, turn milk into yoghurt and cheese and preserve food for thousands of years before anyone knew microbes existed.

In fermentation, yeasts and bacteria break down sugars and give off acids, gases or alcohol. Yeasts, above all Saccharomyces cerevisiae, known as baker's or brewer's yeast, release the carbon dioxide that makes dough rise and the alcohol that turns fruit juice into wine. Lactic-acid bacteria sour milk into yoghurt and cabbage into sauerkraut or kimchi, and the acid keeps harmful microbes away. Residue on pottery from the Neolithic village of Jiahu in China shows a fermented drink of rice, honey and fruit about 9,000 years ago. Many languages took the word yoghurt from Turkish. Only in the 1850s and 1860s did Louis Pasteur show that living microbes cause fermentation, work that led to pasteurisation.

Rockefeller University RockEDURead card
WonderHistory

The 'Three Sisters' are maize, beans and squash, planted together by Indigenous farmers of the Americas so that each crop helps the others grow.

All three crops were first domesticated in Mesoamerica, today's Mexico and Central America: squash about 10,000 years ago, then maize and beans over the following thousands of years. Growing them together later spread across much of North America. Each plant has a job. The maize stalk is a pole for the bean vine to climb; bacteria living in small lumps on the bean roots turn nitrogen from the air into a form plants can use, which enriches the soil; and the broad squash leaves shade the ground, keeping it moist and holding back weeds. Among the Haudenosaunee (Iroquois) of the north-east, the crops appear in stories as three sisters who thrive only together, and a modern experiment found that their traditional mixed planting produced more food energy and protein than any of the crops grown alone.

Smithsonian Folklife FestivalRead card
DriveScience

Gregor Mendel worked out the basic laws of inheritance by breeding pea plants in his monastery garden in Brno, and published his results in 1866. The paper was almost entirely ignored until 1900, sixteen years after his death.

Mendel was an Augustinian friar, and later abbot, at St Thomas's Abbey in Brno, in today's Czech Republic. Over about eight years he grew and cross-bred thousands of pea plants, tracking traits such as seed shape and flower colour across generations, and found that they were passed on in predictable ratios. He presented the results to the Natural History Society of Brno in 1865 and published them the next year, but few readers grasped their importance. Around 1900 three botanists, Hugo de Vries, Carl Correns and Erich von Tschermak, reached similar results and brought his paper to light. The rules he described are still taught as Mendelian inheritance.

History of scienceRead card
DriveScience

Srinivasa Ramanujan, a largely self-taught mathematician working as a clerk in Madras, sent the Cambridge mathematician G. H. Hardy a letter full of new results in 1913. A year later he travelled to England to work with Hardy.

Mathematicians in Madras had already recognised his gift and helped him publish and find support before he left India. At Cambridge, working closely with Hardy, Ramanujan produced striking results in number theory, the study of whole numbers, and in infinite series. Hardy later called their collaboration the one romantic incident in his life. Ramanujan was elected a Fellow of the Royal Society in 1918. His health broke down in England, and he returned to India in 1919; he died the following year, aged 32. His notebooks, full of results written down without proof, kept mathematicians busy for decades, and some of his ideas are still being applied today.

History of mathematicsRead card
WonderHistory

The geographer al-Idrisi completed the Tabula Rogeriana, a world atlas made for King Roger II of Sicily, in 1154. He spent some fifteen years comparing earlier written geography with accounts collected from travellers.

Al-Idrisi was born around 1100, probably in Ceuta, and studied in Córdoba before Roger II invited him to his court in Palermo, where Arabic, Greek and Latin learning met. The book's Arabic title, Nuzhat al-mushtaq, means roughly 'the journey of one eager to cross distant horizons'. It divides the known world into seven climate zones from south to north, each cut into ten sections, giving seventy regional maps with descriptions of roads, ports, distances and trade. As in much Islamic mapmaking of the time, south is at the top. Al-Idrisi also engraved a world map on a large silver disc, now lost. Roger II died only weeks after the work was finished.

Tabula RogerianaRead card
Next card in the archiveGregor Mendel worked out the basic laws of inheritance by breeding pea plants in his monastery garden in Brno, and published his results in 1866. The paper was almost entirely ignored until 1900, sixteen years after his death.Read next →