Science: quotes, facts and reflections - Page 5

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WonderTechnology

Machine learning lets a computer learn a task from examples instead of following rules written by hand. A spam filter, for instance, is shown thousands of emails already marked as spam or not spam, and works out for itself which patterns give spam away.

The term was coined in 1959 by Arthur Samuel, an IBM researcher whose draughts-playing program got better the more it played. A learning system has many internal settings. During training they are adjusted again and again until its answers on the examples are as accurate as possible, and the system then uses them on cases it has never seen. A turning point came in 2012, when AlexNet, a system from the University of Toronto, recognised objects in photos far better than earlier methods, using layered 'neural networks' loosely modelled on the brain. Machine learning now powers translation apps, voice assistants, film and music recommendations and the analysis of medical scans. Because it learns from data, gaps or biases in that data carry through into its answers.

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WonderTechnology

By one widely cited estimate, about 13 sextillion transistors (13 followed by 21 zeros) had been made by 2018, more than any other object in history. A transistor is a tiny electronic switch, and computer chips are built from billions of them.

The first transistor was built at Bell Labs in the United States in 1947 by John Bardeen and Walter Brattain, working in William Shockley's group; the three shared the 1956 Nobel Prize in Physics. Transistors replaced the fragile glass valves of early electronics. A transistor switches an electric current on or off, and those on and off states are the 1s and 0s computers work with. Almost all transistors made today are of a type called the MOSFET, invented at Bell Labs in 1959 by Mohamed Atalla and Dawon Kahng. The 13 sextillion figure is an estimate by the industry analyst Jim Handy, published by the Computer History Museum in 2018. A single advanced chip can now hold more than 100 billion transistors, and billions more are made every day.

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An MRI scanner uses a powerful magnet and pulses of radio waves to make hydrogen atoms in the body give off faint signals, which a computer turns into detailed pictures of the brain, muscles and organs. Unlike X-rays and CT scans, it uses no ionising radiation, the kind that can damage cells.

Most of the body is water and fat, both rich in hydrogen, and the nucleus of each hydrogen atom behaves like a tiny magnet. The scanner's magnet is usually tens of thousands of times stronger than Earth's magnetic field, and inside it these nuclei line up. A radio pulse knocks them out of line; as they settle back they send out weak radio signals. Different tissues settle at different speeds, which gives the images their contrast. The method grew out of nuclear magnetic resonance, a laboratory technique, and 'nuclear' was later dropped from the name because it worried patients, though no radioactivity is involved. Paul Lauterbur and Peter Mansfield, who worked out in the 1970s how to turn the signals into pictures, shared the 2003 Nobel Prize in Physiology or Medicine. The loud knocking during a scan comes from rapidly switched magnetic coils.

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WonderTechnology

A nuclear power station makes electricity from fission, the splitting of heavy atoms such as uranium. The heat released boils water, and the steam spins turbines, just as in a coal or gas plant. Nuclear power supplied about 9 per cent of the world's electricity in 2023.

When an atom of uranium-235, the form of uranium that powers most reactors, absorbs a neutron, one of the particles found in an atom's nucleus, it splits in two, releasing heat and two or three more neutrons. These can split further atoms, a process called a chain reaction. Control rods made of materials that soak up neutrons are moved in or out to keep the reaction steady. The fuel is extremely concentrated: a kilogram of typical reactor fuel holds about 120,000 times as much energy as a kilogram of coal, and the plant gives off almost no carbon dioxide while running. The first plant to feed a power grid opened at Obninsk, near Moscow, in 1954, and Britain's Calder Hall followed in 1956. The difficulties are long-lived radioactive waste, high building costs and the need for strict safety, as the Chernobyl accident in 1986 and Fukushima in 2011 showed.

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In 1928, at St Mary's Hospital in London, Alexander Fleming saw that a stray mould had stopped bacteria growing around it on a lab dish, and later named its active substance penicillin. From 1939 an Oxford team led by Howard Florey and Ernst Chain purified it and proved it could cure infections.

Fleming came back from a holiday in September 1928 to find a dish of Staphylococcus bacteria spoiled by a Penicillium mould, with a clear ring around it where the bacteria had died. He published his findings in 1929 but could not make the substance pure or stable enough to use as a drug. In Oxford, Florey, Chain, Norman Heatley and colleagues learned to grow the mould and extract penicillin, and in May 1940 showed that it protected infected mice. In February 1941 they gave it to their first patient, an Oxford policeman; he improved, but the supply ran out and he died. American factories then scaled up production, and 2.3 million doses were ready for the Normandy landings in 1944. Fleming, Florey and Chain shared the 1945 Nobel Prize in Physiology or Medicine. In his Nobel lecture Fleming warned that taking too little penicillin could make bacteria resistant to it.

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WonderScience

On 8 November 1895, in his laboratory at the University of Würzburg in Germany, Wilhelm Röntgen found invisible rays that pass through skin and flesh but are stopped by bone and metal. He called them X-rays, X for unknown, and in 1901 received the first Nobel Prize in Physics.

Röntgen was passing electricity through a glass tube covered in black cardboard when he noticed a coated screen on a nearby bench begin to glow. For weeks afterwards he almost lived in his laboratory, studying the new rays. About six weeks after the discovery he made an X-ray image of his wife Anna Bertha's hand, showing her bones and her ring, and his paper 'On a New Kind of Rays' appeared on 28 December 1895. News spread within days, and doctors were soon using X-rays to look at broken bones. Röntgen refused to patent the discovery so that everyone could benefit from it. Many languages, including German and Turkish, still name the rays after him, which is why an X-ray is a 'röntgen' in Turkish.

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WonderTechnology

Encryption turns readable data into scrambled code that only someone with the right key can turn back. It protects online banking, card payments and private messages; the padlock many browsers show beside a web address means the page reached you encrypted.

People have hidden messages for thousands of years. Julius Caesar is said to have shifted each letter a fixed number of places along the alphabet, and in the 9th century the Arab scholar al-Kindi showed how to crack such codes by counting how often each letter appears. Modern encryption rests on mathematical problems that even very fast computers cannot solve without the key. For centuries the hard part was sharing a key safely. In 1976 Whitfield Diffie and Martin Hellman published a way for two strangers to agree on a secret key over an open line, the basis of what is called public-key cryptography; British government mathematicians had found similar ideas in secret a few years earlier. Your browser and your bank use this method, in a fraction of a second, every time you log in.

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WonderTechnology

Ordinary computers store information in bits that are either 0 or 1. Quantum computers use qubits, which can be in a combination of 0 and 1 at once, called a superposition, until they are measured. For certain problems, such as simulating molecules, they could be far faster than any ordinary computer.

In 1982 the physicist Richard Feynman suggested that computers built on quantum physics could simulate nature far more efficiently than ordinary ones. In 1994 the mathematician Peter Shor showed that a large quantum computer could break some of the encryption that protects the internet today, which drew wide attention to the field. The hard part is building one. Qubits are extremely fragile: heat or vibration can easily upset their state, a problem called decoherence, so some machines are cooled to about 0.02 degrees above absolute zero, the lowest temperature possible. Today's quantum computers are still small and make many errors, and they are not faster at everyday tasks such as browsing the web or sending email. Researchers hope they will help design new medicines, materials and batteries.

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WonderTechnology

No single company or government owns the internet. It is tens of thousands of independent networks, run by phone companies, universities, businesses and others, that agree to pass data to one another using shared rules called protocols.

Data travels in small chunks called packets, each labelled with its destination, which may take different routes before being put back together. The core rules, known as TCP/IP, were proposed in 1974 by Vint Cerf and Bob Kahn, and the ARPANET, the American research network the internet grew from, switched to them on 1 January 1983. Today the rules are developed by the Internet Engineering Task Force, an open community anyone can join by contributing, while ICANN, a non-profit organisation, coordinates domain names and the numerical addresses that identify connected devices. A message from Istanbul to London may pass through several companies' cables and routers, the machines that send packets on their way, in a fraction of a second.

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WonderTechnology

DNA data storage writes digital files into synthetic DNA, using its four chemical letters, A, C, G and T, in place of a computer's 0s and 1s. A single gram could in theory hold about 215 million gigabytes, but writing and reading DNA is still far too slow and costly for everyday use.

Computers store everything as 0s and 1s. DNA storage translates those into sequences of A, C, G and T, builds the matching strands chemically, and reads them back with the same sequencing machines used in genetics. In 2012 George Church's team at Harvard stored a whole book this way. In 2013 Nick Goldman and colleagues at the European Bioinformatics Institute stored all of Shakespeare's sonnets and an audio clip of Martin Luther King's 'I Have a Dream' speech. The 215 million gigabyte figure comes from DNA Fountain, a method published in 2017 by Yaniv Erlich and Dina Zielinski. Kept cool and dry, DNA can last for thousands of years, which makes it attractive for archives, but in that study writing just two megabytes cost about 7,000 dollars.

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WonderTechnology

On 4 October 1957 the Soviet Union launched Sputnik 1, the first artificial satellite: a polished metal ball 58 cm wide that sent out radio beeps anyone with a receiver could pick up. Its success shocked the United States and started the Space Race.

Sputnik weighed 83.6 kg and circled Earth every 96 minutes. It was launched from Tyuratam in Soviet Kazakhstan, now the Baikonur Cosmodrome, on an R-7 rocket built under the chief designer Sergei Korolev. Radio amateurs around the world tracked its simple signal, and scientists used the way its orbit changed to measure the density of the upper atmosphere. The batteries ran out after 22 days, and on 4 January 1958, after about 1,440 orbits, the satellite burned up as it fell back into the atmosphere. In the United States the launch caused alarm that the Soviets were ahead in technology. America launched its first satellite, Explorer 1, on 31 January 1958 and created NASA later that year. In Russian, 'sputnik' means travelling companion as well as satellite.

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WonderTechnology

A single optical fibre, a glass strand about as thin as a human hair, can carry dozens of separate data streams at once. Each travels on its own wavelength of infrared laser light, a method called wavelength-division multiplexing, which lets one pair of fibres carry more than 16 trillion bits of data a second.

Engineers speak of each signal having its own colour, although the wavelengths used are infrared and invisible to the eye. At the sending end one device combines the beams into a single fibre, and at the far end another splits them apart again, much as a prism splits white light. The idea was first published in 1970, and early laboratory systems combined just two signals. It spread in the 1990s together with the erbium-doped fibre amplifier, a short stretch of fibre laced with the rare-earth metal erbium that boosts all the wavelengths at once without turning them into electrical signals; teams at the University of Southampton and Bell Labs first demonstrated it in 1986 and 1987. Between 1992 and 2001 the capacity of fibre systems doubled about every six months. Telecoms companies can still add capacity by upgrading the equipment at each end instead of laying new cable.

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WonderTechnology

The World Wide Web and the internet are not the same thing. The internet is the global network that links computers together; the web is one service that runs on it: pages you move between by clicking links.

The internet is the network itself: undersea and underground cables, mobile masts, Wi-Fi and routers, the devices that pass data along, all following a shared set of rules called TCP/IP that lets any two connected machines exchange data. The web is one application that uses it. Web pages are written in a language called HTML, each has its own address, or URL, and a browser fetches them using rules called HTTP. Email, video calls, online games and many phone apps travel over the same network without using the web at all. The internet's roots go back to ARPANET, a US research network set up in 1969; the web was proposed by Tim Berners-Lee at CERN in 1989 and first ran there at the end of 1990.

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The Hubble Space Telescope has photographed galaxies whose light set out more than 13 billion years ago. One of them, GN-z11, found in 2015, appears as it was only about 400 million years after the Big Bang, so astronomers can see the universe when it was young.

Light travels at a fixed speed, so looking far into space also means looking back in time. Hubble, a joint project of NASA and the European Space Agency, was launched on 24 April 1990; once a flaw in its main mirror was corrected in 1993, it began sending back sharp images of the distant universe. In December 1995 it stared at one tiny patch of sky for ten days, and the resulting Hubble Deep Field showed about 3,000 galaxies. GN-z11, reported in 2016 by a team led by Pascal Oesch, remained the most distant galaxy known until the James Webb Space Telescope found even earlier ones in 2022. The universe itself is about 13.8 billion years old.

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WonderTechnology

Computers store everything, from text to photos and music, as binary code: long strings of just two digits, 0 and 1. Each digit is a bit, and eight bits make a byte, which can take 256 different values, enough to stand for any letter on a keyboard.

Computers use two digits because an electronic switch is easy to read reliably as either on or off, with current flowing or not; telling ten voltage levels apart would cause far more errors. The German philosopher and mathematician Gottfried Leibniz published an account of binary arithmetic in 1703. In 1937 Claude Shannon, then a master's student at MIT, showed that switching circuits could carry out logic, and his famous 1948 paper on information used the word 'bit', short for binary digit, which he credited to his colleague John Tukey. Whether a pattern of bits means a letter, the colour of a pixel or a sound depends on the agreed format: in the common ASCII code, for example, 01000001 is a capital A.

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Cloud computing means storing files and running programs on computers in large, distant data centres instead of on your own device. Providers rent out that capacity by the hour or by the gigabyte, so anyone from a small start-up to a large bank can use as much computing power as it needs without buying machines.

The idea is older than the name. In 1961 the computer scientist John McCarthy suggested that computing might one day be sold like water or electricity, as a public utility, and in the 1960s organisations already shared one large, expensive central computer, or mainframe, among many users through a method called time-sharing. Engineers had long drawn the telephone network, and later the internet, as a cloud in their diagrams, and the phrase 'cloud computing' appears in a 1996 business plan at the computer maker Compaq. The modern industry took off in 2006, when Amazon Web Services began renting out storage (S3) and computing power (EC2) to any business or developer, who paid only for what they used.

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In 1609 and 1610 Galileo built improved telescopes and saw mountains on the Moon, Venus going through phases like our Moon, and four moons circling Jupiter. These discoveries undermined the old view that the Earth sits still at the centre of the universe.

Galileo first saw Jupiter's moons on 7 January 1610 and announced them that March in a short book, Sidereus Nuncius (The Starry Messenger). He named them the Medicean stars after his future patron, Cosimo II de' Medici; today they are called Io, Europa, Ganymede and Callisto. The phases of Venus were an even stronger argument. In the model of the ancient astronomer Ptolemy, Venus always stays between the Earth and the Sun, so it could never appear fully lit. Galileo watched it pass through a complete set of phases, which only makes sense if Venus orbits the Sun. The debate did not end there: in 1633 the Roman Inquisition found him 'vehemently suspect of heresy' for defending a Sun-centred universe, and he spent the rest of his life under house arrest.

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In an internal combustion engine, fuel burns inside the engine itself. The hot gases expand and push pistons, and the pistons turn a crankshaft that drives the wheels, so the fuel's chemical energy becomes motion.

'Internal' means the fuel burns inside the cylinders, unlike a steam engine, which burns its fuel outside to boil water. Most petrol engines work in four strokes: the piston moves down to draw in fuel and air, moves up to squeeze the mixture, is driven down when a spark from the spark plug ignites it, and rises again to push out the exhaust. Connecting rods turn this up-and-down movement into the turning of the crankshaft. The Belgian-born engineer Étienne Lenoir built a working gas engine in 1860, and Nicolaus Otto developed the first practical four-stroke engine in 1876. In 1886 Karl Benz patented his Motorwagen, widely regarded as the first practical car, which ran on a four-stroke engine. Even today, most of the energy in the fuel is lost as heat rather than turned into motion.

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StillnessLiterature

Imagination is more important than knowledge. Knowledge is limited. Imagination encircles the world.

Einstein said this to the American journalist George Sylvester Viereck, whose interview 'What Life Means to Einstein' appeared in The Saturday Evening Post on 26 October 1929. By then he was world famous: measurements made during the 1919 solar eclipse had confirmed his general theory of relativity, and he had won the 1921 Nobel Prize in Physics. The line follows his remark that he was 'enough of an artist' to draw freely on his imagination. A similar passage appeared in his book Cosmic Religion in 1931.

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WonderHistory

In April 2003 the Human Genome Project, an international effort begun in 1990, announced that it had read the human genome, the full set of genetic instructions in our cells. About 8% was still missing, in long repetitive stretches. The Telomere-to-Telomere Consortium filled the last gaps in 2022 and 2023.

The genome is written in four chemical letters, A, C, G and T, about 3.1 billion of them, and sequencing means reading them in order. The project was led by the United States with the United Kingdom, Japan, France, Germany and China, and cost about 2.7 billion dollars; Bill Clinton and Tony Blair announced a rough draft in June 2000. The machines of the time read DNA in short pieces, which were then fitted together like a jigsaw. Where the same letters repeat over and over, the pieces could not be placed, so those regions stayed blank. A telomere is the tip of a chromosome, and the consortium's name means 'from one end to the other'. Using newer machines that read much longer pieces, it published a gapless sequence of every chromosome except the Y in the journal Science in 2022; the Y followed in 2023.

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WonderLanguage

The Latin verb scire, 'to know', sits behind a surprising family of English words: science, conscience, omniscient, prescient. The odd relative is nice. It comes from nescius, 'not knowing', and when it entered English in the late 1200s it meant foolish or ignorant.

Science first meant simply knowledge of any kind, from Latin scientia. The narrower sense, the study of nature by observation and experiment, came later, and the word 'scientist' was coined only in 1833, by the English scholar William Whewell. Conscience comes from conscientia, 'knowing with', which could mean knowledge shared with others or knowledge held within oneself. Omniscient adds omnis, 'all', and prescient adds prae, 'before'. Nescius is simply ne-, 'not', joined to the same verb, so 'nice' began life as the opposite of 'science'. Turkish has a similar family built on its own verb for knowing, bil-: bilgi (knowledge) and bilge (wise) are old words, while bilim (science) and bilinç (consciousness) were coined during the language reform of the 1930s.

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WonderScience

Voyager 1 and Voyager 2, launched by NASA in 1977, have both crossed into interstellar space, the space between the stars, beyond the bubble of particles blown out by the Sun. They are the only spacecraft known to have got there, and both still send data to Earth.

The Sun constantly blows out a stream of electrically charged particles, the solar wind. It carves a vast bubble in space called the heliosphere, whose outer edge, the heliopause, is where the solar wind meets the thin gas between the stars. Voyager 1 crossed it on 25 August 2012 and Voyager 2 on 5 November 2018, both about 120 times farther from the Sun than Earth is. By August 2026 Voyager 1 was some 25.6 billion kilometres from the Sun, and its radio signals were taking more than 23 hours to reach us. It was expected to pass a full light-day from Earth, the distance light travels in 24 hours, in November 2026. Both probes run on electricity made from the heat of decaying plutonium. That supply shrinks every year, so engineers have been switching instruments off one by one to keep them going.

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WonderScience

Einstein received the 1921 Nobel Prize in Physics not for relativity but for explaining the photoelectric effect, in which light striking a metal knocks electrons out of it. He proposed that light comes in tiny packets of energy, now called photons, an idea at work today in solar panels and camera sensors.

The prize took an unusual path. In 1921 the Nobel committee decided that none of the nominations met its standards, so the prize was held back and awarded a year later, in November 1922, while Einstein was travelling to Japan. Relativity was left out on purpose: it was still controversial, and some committee members doubted that experiments had confirmed it. The photoelectric paper of 1905 had solved a real puzzle. Faint blue or ultraviolet light can knock electrons out of certain metals while bright red light cannot, because each packet's energy depends on the light's colour, not its brightness. The American physicist Robert Millikan confirmed Einstein's equation by experiment in 1916. When Einstein gave his Nobel lecture, in Gothenburg in July 1923, he spoke about relativity anyway. As agreed in their divorce, the prize money went to his first wife, Mileva Marić.

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WonderScience

Marie Curie shared the 1903 Nobel Prize in Physics for research on radioactivity and won the 1911 Nobel Prize in Chemistry alone, for discovering the elements polonium and radium. She was the first person to win two Nobel Prizes, and she is still the only one to win in two different sciences.

She was born Maria Skłodowska in Warsaw in 1867, when Poland was under Russian rule and women could not study at university there, so in 1891 she moved to Paris. With her husband, Pierre, she found that uranium ore gave off more radiation than its uranium alone could explain, and traced the extra to two new elements. She named the first polonium, after Poland. The 1903 prize was shared with Henri Becquerel, who had discovered radioactivity. The committee first planned to honour only the two men, until the Swedish mathematician Gösta Mittag-Leffler alerted Pierre, who insisted that Marie be included. After Pierre was run over by a horse-drawn wagon in Paris in 1906, she took over his post and became the first woman professor at the University of Paris. Her daughter Irène won the Nobel Prize in Chemistry in 1935.

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