by John Lloyd
The Wright Brothers made their famous flights half a century later, in 1903. They were inspired by Cayley and by another unsung hero of aviation, Otto Lilienthal (1848–96), a Prussian known as the ‘Glider King’. He was the first person to fly consistently: in the decade before the Wright Brothers, he made over 2,000 glider flights before falling to his death in 1896. His last words were humble and poignant: ‘Small sacrifices must be made.’
STEPHEN Who invented the aeroplane?
RICH HALL It’s Orville and Wilbur Wright.
**KLAXON** ‘The Wright Brothers’
PETER SERAFINOWICZ Is it the Wrong Brothers?
How many legs does an octopus have?
Two.
Octopuses have eight limbs protruding from their bodies, but recent research into how they use them has redefined what they should be called. Octopuses (from the Greek for ‘eight feet’) are cephalopods (Greek for ‘head foot’). They use their back two tentacles to propel themselves along the seabed, leaving the remaining six to be used for feeding. As result, marine biologists now tend to refer to them as animals with two legs and six arms.
An octopus’s tentacles are miraculous organs. They can stiffen to create a temporary elbow joint, or fold up to disguise their owner as a coconut rolling along the sea floor. They also contain two-thirds of the octopus’s brain – about 50 million neurons – the remaining third of which is shaped like a doughnut and located inside its head, or mantle.
Because so much of an octopus’s nervous system is in its extremities, each limb has a high degree of independence. A severed tentacle can continue to crawl around and, in some species, will live for several months. An octopus’s arm (or leg) quite genuinely has a mind of its own.
Each arm on an octopus has two rows of suckers, equipped with taste-buds for identifying food. An octopus tastes everything that it touches. Male octopuses also have a specialised arm in which they keep their sperm. It’s called the hectocotylus and is used for mating. To transfer the sperm, the male puts his arm into a hole in the female’s head. During copulation the hectocotylus usually breaks off, but the male grows a new one the following year.
The way octopuses mate was first described by Aristotle (384–322 BC) but for over 2,000 years no one believed him. The French zoologist Georges Cuvier (1769–1832) rediscovered the process in the nineteenth century and gave the hectocotylus its name. It means ‘a hundred tiny cups’ in Greek.
Genetic variations sometimes cause octopuses to grow more than eight limbs. In 1998 the Shima Marineland Aquarium in Japan had a common octopus on display that had 96 tentacles. It was captured in nearby Matoya Bay in December 1998 but died five months later. The multi-armed cephalopod managed to lay a batch of eggs before its death. All the offspring hatched with the normal number of arms and legs, but none survived longer than a month.
Octopuses occasionally eat their own arms. This used to be blamed on stress, but is now thought to be caused by a virus that attacks their nervous system.
MEERA SYAL Do you know how octopuses mate?
STEPHEN Tell, tell.
ALAN With difficulty.
MEERA They mate with their third right arm.
ALAN Do they?
MEERA Yes!
CLIVE ANDERSON We all do that.
What colour are oranges?
That depends.
In many countries, oranges are green – even when ripe – and are sold that way in the shops. The same goes for lemons, mangoes, tangerines and grapefruit.
Oranges are unknown in the wild. They are a cross between tangerines and the pomelo or ‘Chinese grapefruit’ (which is pale green or yellow), and were first grown in South-East Asia. They were green there then, and today they still are. Vietnamese oranges and Thai tangerines are bright green on the outside, and only orange on the inside.
Oranges are subtropical fruit, not tropical ones. The colour of an orange depends on where it grows. In more temperate climes, its green skin turns orange when the weather cools; but in countries where it’s always hot the chlorophyll is not destroyed and the fruits stay green. Oranges in Honduras, for example, are eaten green at home but artificially ‘oranged’ for export.
To achieve this, they are blasted with ethylene gas, a by-product of the oil industry, whose main use is in the manufacture of plastic. Ethylene is the most widely produced organic compound in the world: 100 million tons of it are made every year. It removes the natural outer green layer of an orange allowing the more familiar colour to show through.
Far and away the world’s largest producer of oranges is Brazil (18 million tons a year), followed by the USA, which grows fewer than half as many. American oranges come from California, Texas and Florida. They were often synthetically dyed until the Food and Drug Administration banned the practice in 1955.
You can’t tell the ripeness of an orange by its colour, no matter where it’s from. If an orange goes unpicked, it can stay on the tree till the next season, during which time fluctuations in temperature can make it turn from green to orange and back to green again without the quality or flavour being affected.
The oranges you see on display in your supermarket certainly appear to be completely orange, but you may now start to worry they’ve been gassed. Don’t.
Ethylene is odourless, tasteless and harmless, and many fruits and vegetables give it off naturally after they’re picked. Ethylene producers include apples, melons, tomatoes, avocados and bananas. The gas isn’t bad for you, but it can affect other kinds of fruit and veg – which is why you should keep apples and bananas separate from, say, lemons or carrots (and, of course, oranges).
Ethylene has other uses apart from making plastics (and detergents and antifreeze) and altering the colour of an orange. If you want to speed up the ripening process of an unripe mango, keep it in a bag with a banana.
What’s the name of the most southerly point of Africa?
It’s not the Cape of Good Hope.
The residents of nearby Cape Town often have to explain this to visitors. The southernmost point of the continent is the altogether less famous Cape Agulhas, 150 kilometres (93 miles) south-east of the Cape of Good Hope.
The usual reason given for the Cape of Good Hope’s fame (and its name) is that it was the psychologically important point where sailors, on the long haul down the west coast of Africa on their way to the Far East, at last began to sail in an easterly, rather than a southerly, direction.
On the other hand, it might have been an early example of marketing spin.
Bartolomeu Dias (1451–1500), the Portuguese navigator who discovered the Cape of Good Hope and became the first European to make the hair-raising trip around the foot of Africa, named it Cabo das Tormentas (‘Cape of Storms’). His employer, King John II of Portugal (1455–95), keen to encourage others to adopt the new trade route, overruled him and tactfully rechristened it Cabo da Boa Esperança (‘Cape of Good Hope’).
The King died childless, aged only forty. Five years later Bartolomeu Dias also died. He was wrecked in a terrible storm – along with four ships and the loss of all hands – off the very cape he had so presciently named.
Cape Agulhas is equally treacherous. It is Portuguese for ‘Cape of Needles’, after the sharp rocks and reefs that infest its roaring waters. The local town is home to a shipwreck museum that commemorates ‘a graveyard of ships’.
Because of its isolation and rocky, inaccessible beach, the area is rich in wildlife. On land, it is home to the critically endangered micro-frog (Microbatrachella capensis) and the Agulhas clapper (Mirafra (apiata) majoriae), a lark whose mating display involves much noisy wing-flapping.
In the waters offshore, between May and August, the sea boils with billions of migrating South African pilchards (Sardinops sagax). These shoals form one of the largest congregations of wildlife on the planet, equivalent to the great wildebeest migrations on land, and can stretch to be 6 kilometres (3.7 miles) long and 2 kilometres (1.2 miles) wide. Hundreds of thousands of sharks, do
lphins, seals and seabirds travel in the fishes’ wake, snacking on them at will but making little impact on the overall numbers.
Cape Agulhas is at 34° 49' 58" south and 20° 00' 12" east and it is the official dividing point between the Atlantic and Indian oceans. If you sailed past it, along the relatively unimpressive, gradually curving coastline, you probably wouldn’t even notice it but for the cairn that marks the tip’s exact location.
What’s the hardest known substance?
It’s not diamonds any more.
In 2005 scientists at Bayreuth University in Germany created a new material by compressing pure carbon under extreme heat. It’s called hyperdiamond or aggregated diamond nanorods (ADNR) and, although it’s incredibly hard, it looks rather like asphalt or a glittery black pudding.
It’s long been known that one form of pure carbon (graphite) can be turned into another (diamond) by heat and pressure. But the Bayreuth team used neither. They used a third form of pure carbon, fullerite, also known as buckminsterfullerene or ‘buckyballs’. Its sixty carbon atoms form a molecule shaped like a soccer ball, or like one of the geodesic domes invented by the American architect Richard Buckminster Fuller (1895–1983).
The carbon atoms in diamond are arranged in cubes stacked in pyramids; the new substance is made of tiny, interlocking rods. These are called ‘nanorods’ because they are so small – nanos is Greek for ‘dwarf’. Each is 1 micron (one millionth of a metre) long and 20 nanometres (20 billionths of a metre) wide – about 1/50,000th of the width of a human hair.
Subjecting fullerite to extremes of heat (2,220 °C) and compression (200,000 times normal atmospheric pressure) created not only the hardest, but also the stiffest and densest substance known to science.
Density is how tightly packed a material’s molecules are and is measured using X-rays. ADNR is 0.3 per cent denser than diamond.
Stiffness is a measure of compressibility: the amount of force that must be applied equally on all sides to make the material shrink in volume. Its basic unit is the pascal, after Blaise Pascal (1623–62), the French mathematician who helped develop the barometer, which measures air pressure. ADNR’s stiffness rating is 491 gigapascals (GPa): diamond’s is 442 GPa and iron’s is 180 GPa. This means that ADNR is almost three times harder to compress than iron.
Hardness is simpler to determine: if one material can make a scratch mark on another, it’s harder. The German mineralogist Friedrich Mohs (1773–1839) devised the Mohs Hardness scale in 1812. It starts at the softest end with talc (MH1). Lead is fairly soft at MH1½; fingernails are graded MH2½ (as hard as gold); in the middle are glass and knife blades at MH5½. Ordinary sandpaper (which is made of corundum) is MH9, and right at the top end is diamond at MH10. Since ADNR can scratch diamond, it is literally off the scale.
And there’s more disappointing news for diamond fans: they aren’t ‘forever’. Graphite (which, oddly enough, is one of the softest known substances, as soft as talc) is much more chemically stable than diamond. In fact all diamonds are very slowly turning into graphite. But the process is imperceptible. There’s no danger of anybody suddenly finding their earrings have become pencils.
What’s the strangest substance known to
science?
H2O.
Water, or hydrogen oxide, is the strangest substance known to science. With the possible exception of air, it’s also the most familiar. It covers 70 per cent of the earth and accounts for 70 per cent of our own brains.
Water is oxygen linked to hydrogen (the simplest and most common element in the universe) in the simplest way possible. Any other gas combined with hydrogen just produces another gas: only oxygen and hydrogen make a liquid.
And it’s a liquid that behaves so differently from any other that theoretically it shouldn’t exist. There are sixty-six known ways in which water is abnormal, the most peculiar being that nothing else in nature is found simultaneously as liquid, solid and gas. A sea full of icebergs under a cloudy sky may appear natural, but in chemical terms it is anything but. Most substances shrink as they cool, but when water falls below 4 °C it starts to expand and become lighter. That’s why ice floats, and why wine bottles burst if left in the freezer.
Each water molecule can attach itself to four other water molecules. Because water is so strongly bonded, a lot of energy is needed to change it from one state to another. It takes ten times more energy to heat water than iron.
Because water can absorb a lot of heat without getting hot, it helps keep the planet’s climate steady. Temperatures in the oceans are three times more stable than on land and water’s transparency allows light to penetrate its depths, enabling life in the sea. Without water there would be no life at all. And, though you can put your hand right through it, it’s three times harder to compress than diamonds and water hit at speed is as hard as concrete.
Although the bonds between water molecules are strong, they aren’t stable. They are constantly being broken and remade: each molecule of water collides with other water molecules 10,000,000,000,000,000 times a second.
So many things can be dissolved in water that it’s known as the ‘universal solvent’. If you dissolve metal in acid, it’s gone forever. If you dissolve plaster in water, when all the water has evaporated, the plaster is still there. This ability to dissolve stuff without eradicating it also paradoxically makes water the most destructive substance on the planet. Sooner or later, it eats away everything – from an iron drainpipe to the Grand Canyon.
And it gets everywhere. There are substantial deposits of ice on the moon and on Mars: traces of water vapour have even been detected on the cooler patches of the sun’s surface. On Earth only a tiny fraction of all the water is in the atmosphere. If it fell evenly throughout the world, it would produce no more than 25 millimetres or an inch of rain. Most of Earth’s water is inaccessible, locked deep inside the planet, carried down when tectonic plates overlap, or held inside the mineral structure of the rocks themselves.
If this hidden water were released it would refill the oceans thirty times over.
At what temperature does water freeze?
Pure water doesn’t freeze at 0 °C, nor does seawater.
For water to freeze, it needs something for its molecules to latch on to. Ice crystals form around ‘nuclei’, such as small particles of dust. If there are none of these, you can get the temperature of water down to –42 °C before it freezes.
Cooling water without freezing it is known as ‘supercooling’. It has to be done slowly. You can put a bottle of very pure water in your freezer and supercool it. When you take the bottle out and tap it, the water will instantly turn to ice.
Cooling water extremely fast has a completely different effect. It bypasses the ice stage (which has a regular crystalline lattice structure) and transforms into a chaotic amorphous solid known as ‘glassy water’ (so called because the random arrangement of molecules is similar to that found in glass). To form ‘glassy water’ you need to get the water temperature down to –137 °C in a few milliseconds. You won’t find glassy water outside the lab on Earth, but it’s the most common form of water in the universe – it’s what comets are made of.
Because of its high salt content, seawater regularly falls below 0 °C without freezing. The blood of fishes normally freezes at about –0.5 °C, so marine biologists used to be puzzled by how fish survived in polar oceans. It turns out that species like Antarctic icefish and herring produce proteins in the pancreas that are absorbed into their blood. These prevent the formation of ice nuclei (much like antifreeze in a car radiator).
Given the peculiarities of water at low temperatures, it won’t surprise you to learn that the boiling point of water, even at normal pressure, isn’t necessarily 100 °C either. It can be much more. Again, the liquid needs to be warmed slowly and in a container that has no scratches. It is these that contain the small pockets of air around which the first bubbles form.
Boiling happens when bubbles of water vapour expand and break
the surface. For this to happen, the temperature must be high enough for the pressure created by the vapour bubble to exceed the atmospheric pressure. Under normal conditions this is 100 °C, but if the water is free of places where bubbles could form, more heat is needed to overcome the surface tension of the bubbles as they struggle into life. (It’s the same reason that blowing up a balloon is always harder at the beginning.)
This explains why a boiling hot cup of coffee in the microwave can explode all over you once removed or stirred. The movement sets off a chain reaction, so that all the water in the coffee vaporises at high speed.
One last watery oddity: hot water freezes faster than cold water. Aristotle first noted this in the fourth century BC, but it was only accepted by modern science in 1963. This resulted from the persistence of a Tanzanian schoolboy called Erasto Mpemba, who proved it by repeatedly demonstrating that a hot ice cream mixture set more quickly than cold. We still don’t know why it does.
Where is the largest known lake?
It’s 842 million miles away, halfway across the solar system.
In 2007 the Cassini–Huygens space probe sent back pictures of Titan, the largest of Saturn’s moons. Near the moon’s northern pole, radar imaging revealed a giant lake estimated to cover 388,500 square kilometres (150,000 square miles), significantly bigger than the Caspian Sea, the largest lake on Earth at 370,400 square kilometres (143,244 square miles).
The lake is called Kraken Mare – mare is Latin for ‘sea’ and the kraken is a sea monster from Norse mythology.
Titan has many lakes and they are the only bodies of stable liquid known to exist anywhere other than on Earth. But the liquid isn’t water: Titan’s average temperature is –181°C, so any water would be frozen solid. They are lakes of liquid gas – methane and ethane, the main ingredients of natural gas on earth – and they are so cold that they may even contain frozen methane-bergs.