Science: quotes, facts and reflections - Page 8

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WonderScience

About 90% of the glass made today is soda-lime glass: roughly 73% silica from sand, 14% soda and 9% lime, melted together and cooled before the atoms can line up into crystals. The result is an amorphous solid, hard like a crystal but with its atoms jumbled like a liquid's.

Pure silica only melts at about 1,700 °C and is hard to work, so glassmakers add soda (sodium carbonate), which lowers the melting temperature. Soda alone would make glass that slowly dissolves in water, so lime, from limestone, is added to make it durable. Modern furnaces run at up to about 1,575 °C. Glassmaking goes back more than 4,000 years in Mesopotamia and Egypt, where the first glass objects were beads. Blowing molten glass through a pipe, invented in the 1st century BC, made cups and bottles cheap. Most window glass today is float glass, made by pouring molten glass onto a bath of molten tin, a method developed in England by Alastair Pilkington's team in the 1950s. The old story that church windows are thicker at the bottom because glass slowly flows is a myth: at room temperature glass does not flow measurably.

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The Moon and Mars have been mapped in finer detail than most of Earth's ocean floor, because the radar and cameras that map planets from orbit cannot see through seawater.

Orbiting spacecraft have imaged the entire surfaces of the Moon and Mars in detail. On Earth, ships have to map the seabed with sonar, timing how long pulses of sound take to bounce back from the bottom, and a ship covers only a narrow strip at a time. Satellites can estimate the seafloor's shape from tiny bumps in the sea surface caused by the gravity of undersea mountains, but only at a resolution of several kilometres. The Nippon Foundation–GEBCO Seabed 2030 project, launched in 2017 to gather the world's depth measurements into one map, reported that about 6% of the seafloor had been mapped to modern standards at the start, and roughly a quarter by 2024.

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WonderScience

Roughly half of the oxygen produced on Earth comes from the ocean, most of it made by phytoplankton, microscopic drifting organisms that photosynthesise like plants.

Phytoplankton are mostly single-celled algae and bacteria living in the sunlit top layer of the sea. Like land plants, they use sunlight to turn carbon dioxide and water into sugar, releasing oxygen. Estimates of their share of the planet's oxygen production range from about 50% to 80%, because it is hard to measure. One tiny bacterium alone, Prochlorococcus, may produce up to a fifth of it. Most of the oxygen made in the sea, though, is used up again by marine animals and microbes and by the decay of dead matter, so the ocean's net contribution to the air we breathe is much smaller than the headline figure suggests.

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WonderScience

The Mariana Trench in the western Pacific is so deep that Mount Everest could fit inside it with more than two kilometres of water above its peak.

The trench's deepest point, the Challenger Deep, lies about 10,935 metres below the surface, according to measurements made during dives between 2019 and 2021. Everest stands 8,849 metres high, so its summit would still be around 2,000 metres under water. The trench forms where the Pacific plate slides beneath the smaller Mariana plate. The first people to reach the bottom were Jacques Piccard and Don Walsh, in the deep-diving vessel Trieste in 1960; the film director James Cameron made a solo dive in 2012, and the explorer Victor Vescovo has dived there several times since 2019. The water pressure at the bottom is more than a thousand times that at sea level.

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WonderScience

Earth's longest mountain range is the mid-ocean ridge, a chain of undersea volcanic mountains about 65,000 kilometres long that winds around the globe, almost all of it beneath the sea.

The ridge runs along the seams where tectonic plates, the huge slabs of Earth's outer shell, are moving apart, usually by a few centimetres a year. As they separate, molten rock rises into the gap, cools and becomes new ocean floor, a process called seafloor spreading. In the 1950s the American geologist Marie Tharp, drawing maps with Bruce Heezen from ships' sonar soundings, noticed a deep valley running along the ridge's crest. She argued it was a rift where the crust was pulling apart; the idea was doubted at first, but in the 1960s it became key evidence for plate tectonics. Iceland is one of the few places where the ridge rises above sea level.

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WonderScience

On the deep seabed, hot springs called hydrothermal vents support whole communities of animals without any sunlight. Bacteria there make food from chemicals in the vent water, and the animals live on the bacteria.

Vents form near volcanic ridges, where seawater seeps into cracks in the ocean floor, is heated by magma below and gushes back out full of dissolved minerals. The first were found in 1977, when scientists diving in the submersible Alvin near the Galápagos Islands came upon warm vents crowded with giant tube worms, clams and crabs. Two years later, vents on the East Pacific Rise were found spouting black, mineral-laden water at about 350°C. The bacteria live by chemosynthesis: instead of sunlight, they draw energy from chemicals such as hydrogen sulphide. The discovery showed that life can thrive without the Sun, and it now shapes the search for life on ocean moons such as Jupiter's Europa.

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WonderScience

Robert Ballard, the ocean explorer who found the wreck of the Titanic in 1985, has argued that the seabed holds more history than all the world's museums combined.

UNESCO estimates that about three million shipwrecks lie on the ocean floor, left by thousands of years of trade, war and storms. In places such as the oxygen-poor depths of the Black Sea, wooden ships more than 2,000 years old survive almost intact. Ballard, an American oceanographer and former US Navy officer, found the Titanic on a joint expedition with the French research institute Ifremer, using Argo, a camera sled towed behind a ship. He went on to locate the German battleship Bismarck in 1989 and John F. Kennedy's wartime patrol boat PT-109 in 2002. In 2008 he founded the Ocean Exploration Trust, whose ship Nautilus streams its deep-sea dives live online.

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WonderScience

The ocean holds about 97 percent of Earth's water, yet people have directly seen less than 0.001 percent of the deep seafloor, an area about a tenth the size of Belgium.

The remaining 3% or so of Earth's water is fresh, and most of that is locked in ice caps, glaciers and groundwater. The seafloor figure comes from a 2025 study in Science Advances, which gathered records of nearly 44,000 dives deeper than 200 metres by crewed submersibles, robots and towed cameras since the 1950s. Sonar can map the shape of the seabed from a ship, but actually seeing it needs lights and cameras a few metres from the bottom, and each dive covers only a narrow strip. The dives were also unevenly spread: about two-thirds of the observations lie within 200 nautical miles of just three countries, the United States, Japan and New Zealand.

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WonderScience

The Great Barrier Reef, off Australia's north-east coast, is the world's largest coral reef system and stretches for more than 2,300 kilometres.

The reef is built by coral polyps, soft animals a few millimetres across that are related to sea anemones. Each polyp surrounds itself with a hard cup of limestone, and over thousands of years billions of these skeletons have piled up into a system of about 2,900 separate reefs and 900 islands, big enough to be seen from space. Reef-building corals get much of their food from tiny algae living in their tissue, which also give them their colour. When the water stays too warm, corals expel these algae and turn white, which is called bleaching; the reef suffered mass bleaching five times between 2016 and 2024. It became a UNESCO World Heritage Site in 1981.

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WonderScience

Ocean tides are caused mainly by the Moon: it pulls more strongly on the side of Earth facing it than on the far side, and that difference stretches the oceans. The Sun adds an effect a little under half as strong.

The stretching raises two bulges of water, one facing the Moon and one on the opposite side of Earth. As the planet turns, coasts pass through both, which is why many places have two high and two low tides a day. At new and full moon the Sun and Moon line up, their effects add together and the difference between high and low water is greatest, called spring tides; at half moon they pull at right angles and the range is smallest, called neap tides. The shape of the coast then changes everything: in Canada's funnel-shaped Bay of Fundy the water can rise and fall by about 16 metres, the largest tidal range in the world.

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WonderScience

Sound travels about four times faster in seawater than in air: roughly 1,500 metres per second, against about 340 in air.

Sound is a wave of pressure passed from molecule to molecule. It travels faster through materials that resist being squeezed, and water is far harder to compress than air. Water is also much heavier than air, which on its own would slow sound down, but its stiffness wins by a wide margin. In the sea the speed also changes with temperature, pressure and saltiness. In many oceans, around 1,000 metres down, these effects create a layer called the SOFAR channel, which bends sound back towards its centre and lets low sounds travel thousands of kilometres. Navies have used it to track submarines and detect distant explosions, and some whales' low calls may carry hundreds of kilometres through it.

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WonderScience

And yet it moves.

The words 'Eppur si muove', 'and yet it moves', meaning the Earth, first appear in print in 1757, in Giuseppe Baretti's The Italian Library, more than a century after Galileo's trial. In 1633 the Roman Inquisition forced Galileo, then 69, to renounce the view that the Earth moves around the Sun, and sentenced him to house arrest for life. No record from the time has him muttering the line, though a painting said to date from the 1640s, found in 1911, bears the words.

Attributed to Galileo; first recorded by Giuseppe Baretti (1757)Read card

WonderScience

Measure what is measurable, and make measurable what is not so.

Galileo never wrote this. The historian Andreas Kleinert showed in 2009 that the maxim comes from two 19th-century French scholars, Antoine-Augustin Cournot (1847) and Thomas-Henri Martin (1868), who used it to sum up Galileo's method. The German mathematician Hermann Weyl spread it in English in the late 1940s. It does describe what Galileo did: in his inclined-plane experiments he timed balls rolling down a ramp by weighing the water that ran from a vessel, turning motion into numbers.

Galileo Galilei (attributed)Read card

StillnessScience

If I have seen further it is by standing on the shoulders of giants.

Newton wrote this in a letter to Robert Hooke dated 5 February 1676, during a tense exchange over their rival theories of light and colour. The image was already old: John of Salisbury recorded in 1159 that the scholar Bernard of Chartres likened his generation to dwarfs on the shoulders of giants, able to see further thanks to those before them. Some historians suspect a dig at Hooke, who was short, but there is no proof. Newton (1643–1727) went on to set out the laws of motion and gravity.

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StillnessScience

I can calculate the motion of heavenly bodies, but not the madness of people.

The earliest source is a note by the writer Joseph Spence, made around 1756 and first published in 1820: Lord Radnor told him that when Newton was asked how long South Sea Company shares would keep rising, he said he could not calculate the madness of the people. The comparison with heavenly bodies appears only in later retellings. The company's shares soared and then crashed in 1720, the South Sea Bubble. Newton is said to have lost about £20,000, a figure first printed in 1797.

Attributed to Newton after the South Sea Bubble; no contemporary recordRead card

WonderScience

From so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved.

This ends the last sentence of On the Origin of Species (1859), the book in which the English naturalist Charles Darwin (1809–1882) set out evolution by natural selection. The closing paragraph begins with an ‘entangled bank’: a patch of ground crowded with plants, singing birds, insects and worms. Darwin asks the reader to see that all these intricate forms were produced by laws still acting around us, spreading from a few simple forms, or perhaps one. From the second edition onwards he added the words ‘by the Creator’ to that final sentence.

Charles DarwinRead card

StillnessScience

Nothing in life is to be feared, it is only to be understood.

Attributed to Marie Curie (1867–1934), the Polish-born French physicist and chemist who won Nobel Prizes in both physics (1903) and chemistry (1911). It often circulates with a second sentence: ‘Now is the time to understand more, so that we may fear less.’ No letter, lecture or interview containing it has been found. It fits her work, all the same: she spent decades measuring radioactivity when its dangers were barely understood, and she died of aplastic anaemia, a failure of the bone marrow now linked to her long exposure to radiation.

Marie Curie (attributed)Read card

WonderScience

Somewhere, something incredible is waiting to be known.

The sentence closes 'Seeking Other Worlds', a Newsweek article about the astronomer Carl Sagan published on 15 August 1977 and written by David Gelman with Sharon Begley and two other reporters. It was not in quotation marks: it was the writers' own summing-up. In 2015 Begley told Garson O'Toole, who runs the Quote Investigator website, that she had written it, because Newsweek had a nearly firm rule against ending a story on a quotation. Detached from the article, the line spread as Sagan's own words and is still widely quoted as his.

Sharon Begley, Newsweek profile of Carl Sagan (1977)Read card

WonderScience

We are a way for the cosmos to know itself.

Sagan says this a few minutes into the first episode of Cosmos: A Personal Voyage, the thirteen-part television series he co-wrote and presented in 1980; it has since been broadcast in more than 60 countries. The idea behind the line is sound science: apart from hydrogen, which dates from the Big Bang, most of the atoms in our bodies, including carbon, oxygen and iron, were made inside earlier generations of stars and scattered when those stars died. Carl Sagan (1934–1996) was an American astronomer at Cornell University who worked on NASA's Viking and Voyager missions.

Carl SaganRead card

WonderScience

I would rather have questions that can't be answered than answers that can't be questioned.

The line is widely credited to Richard Feynman (1918–1988), the American physicist who shared the 1965 Nobel Prize in Physics for his work on quantum electrodynamics, the theory of how light and matter interact. No one has found it in his books, lectures or recorded interviews. It survives because it sounds like him. In the 1981 BBC Horizon film The Pleasure of Finding Things Out, he said he could live with doubt and not knowing, and found that far more interesting than holding answers that might be wrong.

Richard Feynman (attributed)Read card

StillnessScience

The first principle is that you must not fool yourself — and you are the easiest person to fool.

Richard Feynman gave 'Cargo Cult Science' as the commencement address at Caltech, the California Institute of Technology, in 1974. The title refers to cargo cults in parts of Melanesia: after the Second World War, some islanders who had watched military airfields receive planeloads of supplies built imitation runways and huts, with a man wearing wooden 'headphones', hoping the planes would come back. Feynman's point was that some research copies the outward form of science without its core, which is an honest effort to find everything that could prove your own result wrong. Right after this line, he urges scientists to report such evidence too.

Richard Feynman, 'Cargo Cult Science' (1974)Read card

WonderScience

Look up at the stars and not down at your feet.

Stephen Hawking (1942–2018), the Cambridge physicist who lived with motor neurone disease for more than fifty years, gave this as the first of three pieces of advice to his children in a 2010 ABC News interview with Diane Sawyer. The other two: never give up work, because it gives life meaning and purpose, and if you are lucky enough to find love, do not throw it away. At the opening ceremony of the London 2012 Paralympic Games he repeated the line and added: be curious; there is no such thing as a standard human being, but we share the same human spirit.

Stephen Hawking, interview (2010); Paralympics (2012)Read card

StillnessScience

Only if we understand can we care. Only if we care will we help.

Goodall (1934–2025) often completed the sequence with a third line: only if we help shall all be saved. The idea grew out of her years at Gombe in Tanzania, where she came to know individual chimpanzees by name, character and family. When their numbers fell through forest loss, the bushmeat trade (hunting wild animals for meat to sell) and the capture of infants as pets, she felt it as the loss of individuals she knew, not as a statistic. The same thinking shaped Roots & Shoots, the youth programme she started in Tanzania in 1991, in which young people learn about a local problem and then act on it.

Jane GoodallRead card

WonderScience

Botanically, a banana is a berry: it grows from a single flower's single ovary and holds its seeds inside. A strawberry is not a berry at all, and the tiny 'seeds' on its skin are its real fruits.

Botanists sort fruits by how they develop from a flower. A true berry grows from one flower with a single ovary, and its whole wall becomes soft flesh around the seeds. By that rule bananas, grapes, tomatoes, avocados and peppers are all berries. A strawberry's red flesh is the swollen tip of the flower stalk, called the receptacle, so it is known as an accessory or false fruit; the real fruits are the dry specks on its surface, called achenes, each holding one seed. Raspberries and blackberries fail for another reason: each is a cluster of tiny fruits from one flower's many separate ovaries. Everyday food names simply answer a different question.

BotanyRead card