by John Lloyd
Every self-respecting neurologist has their own opinion about whether there are more than these nine. Some argue that there are up to twenty-one. What about hunger? Or thirst? The sense of depth, or the sense of meaning, or language? Or the endlessly intriguing subject of synaesthesia, where senses collide and combine so that music can be perceived in colour?
And what about the sense of electricity, or even impending danger, when your hair stands on end?
There are also senses which some animals have but we don’t. Sharks have keen electroception which allows them to sense electric fields, magnetoception detects magnetic fields and is used in the navigation systems of birds and insects, echolocation and the ‘lateral line’ are used by fish to sense pressure, and infrared vision is used by owls and deer to hunt or feed at night.
ALAN What about the ‘sixth sense’?
STEPHEN That’s right. Yeah, it’s an old phrase, because in those days, they only thought of five senses.
ALAN So, what, it’d be … It should be the ‘twenty-second sense’?
How many states of matter are there?
Three, that’s easy. Solid, liquid, gas.
Actually, it’s more like fifteen, although the list grows almost daily.
Here’s our latest best effort:
solid, amorphous solid, liquid, gas, plasma, superfluid, supersolid, degenerate matter, neutronium, strongly symmetric matter, weakly symmetric matter, quark-gluon plasma, fermionic condensate, Bose-Einstein condensate and strange matter.
Without going into impenetrable (and, for most purposes, needless) detail, one of the most curious is Bose-Einstein condensate.
A Bose-Einstein condensate or ‘bec’ occurs when you cool an element down to a very low temperature (generally a tiny fraction of a degree above absolute zero (–273 °C, the theoretical temperature at which everything stops moving).
When this happens, seriously peculiar things begin to happen. Behaviour normally only seen at atomic level occurs at scales large enough to observe. For example, if you put a ‘bec’ in a beaker, making sure to keep it cold enough, it will actually climb the sides and de-beaker itself.
This, apparently, is a futile attempt to reduce its own energy (which is already at its lowest possible level).
Bose-Einstein condensate was predicted to exist by Einstein in 1925, after studying the work of Satyendra Nath Bose, but wasn’t actually manufactured until 1995 in America – work that earned its creators the 2001 Nobel Prize. Einstein’s manuscript itself was only rediscovered in 2005.
What is the normal state of glass?
It’s a solid.
You may have heard it said that glass is a liquid which has cooled but not crystallised, and which just flows fantastically slowly. This is untrue – glass is a bona fide solid.
In support of the assertion that glass is a liquid, people often point to old church windows, where the glass is thicker at the bottom of the pane.
The reason for this is not that the glass has flowed over time, but that medieval glaziers sometimes couldn’t cast perfectly uniform sheets of glass. When that happened, they preferred to stand the glass into the window with the thick edge at the bottom, for obvious reasons.
The confusion about whether glass is a liquid or solid stems from a misreading of the work of German physicist Gustav Tammann (1861–1938) who studied glass and described its behaviour as it solidifies.
He observed that the molecular structure of glass is irregular and disordered, unlike the neat arrangement of molecules in, say, metals.
Reaching for an analogy, he compared it to ‘a frozen supercooled liquid’. But saying glass is like a liquid doesn’t mean it is a liquid.
These days, solids are categorised as either crystalline or amorphous. Glass is an amorphous solid.
Which metal is liquid at room temperature?
As well as mercury, gallium, caesium and francium can all be liquids at room temperature. As these liquids are very dense (being metals), bricks, horseshoes and cannon balls theoretically float in them.
Gallium (Ga) was discovered by French chemist Lecoq de Boisbaudran in 1875. Everyone assumed it was a patriotic name but gallus is Latin for ‘a Gaul’ and ‘rooster’ – as in ‘Lecoq’. It was the first new element to confirm Dmitri Mendeleev’s prediction of the periodic table. Gallium is used chiefly in microchips because of its strange electronic properties. Compact disc players also make use of it because when mixed with arsenic it transforms an electric current directly into laser light, which is used to ‘read’ the data from the discs.
Caesium (Cs) is most notably used in atomic clocks – it is used to define the atomic second (see page 220) It also explodes extremely violently when it comes into contact with water. Caesium’s name means ‘sky blue’ because of the bright blue lines it produces as part of its spectrum. It was discovered in 1860 by Robert Bunsen using the spectroscope he had invented with Gustav Kirchoff, the man who had earlier discovered that signals travel down telegraph wires at the speed of light.
Francium (Fr) is one of the rarest elements: it has been calculated there are only ever thirty grams of it present on Earth. This is because it is so radioactive it quickly decays into other, more stable elements. So it is a liquid metal, but not for very long – a few seconds at most. It was isolated in 1939 by Marguerite Perey at the Curie Institute in Paris. It was the last element to be found in nature.
These elements are liquid at unusually low temperatures for metals because the arrangement of electrons in their atoms makes it hard for them to get close enough to each other to form a crystalline lattice.
Each atom floats around freely, without being attracted to its neighbours, which is exactly what happens in other liquids.
DAVID MITCHELL Didn’t Edward VII take a lot of mercury?
STEPHEN I think he might have done, yes.
DAVID I thought that was for constipation. Drink an incredibly heavy liquid and force the poo down. An alternative would be: stand on your hands and have a load of helium. […] Just need some footmen with nets to catch the turds. ‘Don’t let it get on the tapestries!’
Which metal is the best conductor?
Silver.
The best conductor of both heat and electricity is also the most reflective of all the elements. Its drawback is that it is expensive. The reason we use copper wire in our electrical equipment is because copper – the second most conductive element – is much cheaper.
As well as its decorative uses, silver is now mostly used in the photographic industry, for long-life batteries and for solar panels.
Silver has the curious property of sterilising water. Only tiny amounts are needed – just ten parts per billion. This remarkable fact has been known since the fifth century BC when Herodotus reported that the Persian king Cyrus the Great travelled with his own personal water supply taken from a special stream, boiled, and sealed in silver vessels.
Both the Romans and Greeks noticed that food and drink put in silver containers did not spoil so quickly. Silver’s strong antibacterial qualities were made use of for many centuries before bacteria were discovered. This may also explain why silver coins are often found at the bottom of ancient wells.
A word of caution before you start filling your silver tankard.
First, while silver will certainly kill bacteria in the lab, whether or not it will do so in the body is controversial. Many of the supposed advantages are unproven: the US Food and Drug Administration has forbidden companies from advertising health benefits.
Second, there is a disease called argyria which is linked to the intake of silver particles diluted in water, the most obvious symptom of which is a conspicuously blue skin.
On the other hand, silver salts in swimming pools are a safe substitute for chlorine and, in the US, athletes’ socks are impregnated with silver to stop their feet smelling.
Water is an exceptionally poor conductor of electricity, especially pure water, which is actually used as an insulator. What conducts the el
ectricity is not the H2O molecules but the chemicals dissolved in it – salt, for example.
Sea water is a hundred times better at conducting electricity than fresh water, but it’s a million times worse at conducting electricity than silver.
What’s the densest element?
It’s either osmium or iridium, depending on how you measure it.
The two metals are extremely close in density and have changed places several times over the years. The third-densest element is platinum, followed by rhenium, neptunium, plutonium and gold. Lead is way, way down the list – it’s only half as dense as either osmium or iridium.
Osmium (Os) is a very rare, very hard, silvery-blue metal discovered (along with iridium) in 1803 by the English chemist Smithson Tennant (1761–1815).
Tennant was a vicar’s son from Richmond who was also the first man to show that diamond is a form of pure carbon.
He named osmium from osme, Greek for smell. It gives off highly toxic osmium tetroxide, which has a pungent, irritating odour and can damage the lungs, skin and eyes and cause intense headaches. Osmium tetroxide has been used in fingerprinting because its vapour reacts with minute traces of oil left by the fingers to form black deposits.
Its extreme hardness and resistance to corrosion made osmium useful in the manufacture of long-life gramophone styluses, compass needles and the nibs of quality fountainpens – hence the trade name Osmiroid.
Osmium also has an unusually high melting point of 3,054 °C. In 1897, this inspired Karl Auer to create an osmium electric light-bulb filament to improve on the bamboo one used by Edison. Osmium was eventually replaced by tungsten, which melts at 3,407 °C. The name Osram was registered by Auer in 1906. It derives from OSmium and WolfRAM, the German for tungsten.
Less than 100 kg (220 lb) of osmium are produced worldwide every year.
Iridium (Ir) is a yellowish white metal which, like osmium, is closely related to platinum. The name comes from iris, Greek for rainbow, because of the many beautiful colours its compounds produce.
Iridium also has an extremely high melting point (2,446 °C) and is mainly used to make crucibles for metal foundries and to harden platinum. Iridium is one of the rarest elements on earth (eighty-fourth out of ninety-two) but improbably large amounts of it are found in the thin geological layer known as the KT boundary laid down about 65 million years ago.
Geologists have confirmed this can only have come from space, and it adds support to the theory that an asteroid impact caused the extinction of the dinosaurs.
Where do diamonds come from?
Volcanoes. All diamonds are formed under immense heat and pressure beneath the earth and are brought to the surface in volcanic eruptions.
They are formed between 160 km to 480 km (about 100 to 300 miles) underground. Most are found inside a volcanic rock called Kimberlite, and mined in areas where volcanic activity is still common. Any other diamonds are found loose, having been washed out of their original Kimberlite.
Twenty countries in the world produce diamonds. South Africa is now the fifth largest after Australia, the Democratic Republic of the Congo, Botswana and Russia.
Diamonds are made of pure carbon. So is graphite, the stuff that the ‘lead’ in pencils is made from, but with the carbon atoms arranged differently. Diamond is one of the hardest naturally occurring substances on earth with a score of ten on the Mohs Hardness scale, but graphite is one of the softest with a score of one and a half, only just harder than talcum powder.
The largest known diamond is 4,000 km (2,500 miles) across and measures ten billion trillion trillion carats. Found directly above Australia (eight light years away) the diamond sits inside the star ‘Lucy’ in the constellation Centaurus.
‘Lucy’ got its nickname from the Beatles classic ‘Lucy in the Sky with Diamonds’, but its technical name is white dwarf BPM 37093. The Beatles song was named after a picture drawn by John Lennon’s son Julian of his four-year-old friend Lucy Richardson.
Diamonds were once the world’s hardest known material. However, in August 2005, scientists in Germany managed to create a harder one in a laboratory. Called aggregated carbon nanorods (ACNR), it was made by compressing and heating super-strong carbon molecules to 2,226 °C.
Each of these molecules comprises sixty atoms that interweave in pentagonal or hexagonal shapes; they’re said to resemble tiny footballs. ACNR is so tough it scratches diamonds effortlessly.
How do we measure earthquakes?
The MMS Scale.
In the last decade, the Richter scale has been superseded in seismological circles by the Moment Magnitude Scale or MMS.
The MMS was devised in 1979 by seismologists Hiroo Kanamori and Tom Hanks (no relation) of the California Institute of Technology, who found the Richter scale unsatisfactory because it only measures the strength of the shock waves, which do not fully describe an earthquake’s impact. On the Richter scale, large earthquakes may have the same score but cause wildly different degrees of devastation.
The Richter scale measures the seismic waves or vibration as experienced 600 km (373 miles) away. It was devised in 1935 by Charles Richter, who was also, like Kanamori and Hanks, a Caltech seismologist. He developed it with Beno Gutenberg, the first man to measure accurately the radius of the Earth’s core. Gutenberg died of flu in 1960 without living to measure the Great Chilean Earthquake (the largest ever recorded, which took place four months later).
The MMS, by contrast, is an expression of the energy released by an earthquake. It multiplies the distance of the slip between the two parts of the fault by the total area affected. It was designed to give values that make sense when compared to their Richter equivalent.
Both scales are logarithmic: a two-point increase means 100 times more power. A hand grenade scores 0.5 on the Richter scale, the Nagasaki atom bomb 5.0. The MMS is only used for large earthquakes, above 3.5 on the Richter scale.
According to the US Geological Survey, on the basis of the area of damage (600,000 square km or 231,660 square miles) and the area it was felt in (5,000,000 square km or 1,930,502 square miles) the largest known earthquakes in North America were the little-known Mississippi River valley earthquakes of 1811–12. They created new lakes and changed the whole course of the Mississippi. The area of strong shaking was ten times larger than that in San Francisco in 1906. Church bells rang spontaneously as far away as Massachusetts.
It is impossible to predict when an earthquake will happen. One expert claims that the best way is to count the number of missing cats and dogs in the local newspaper.
Britain has up to 300 earthquakes a year but they are so small that the public notices only about 10 per cent of them.
What’s the commonest material in the world?
a) Oxygen
b) Carbon
c) Nitrogen
d) Water
None of the above. The answer is perovskite, a mineral compound of magnesium, silicon and oxygen.
Perovskite accounts for about half the total mass of the planet. It’s what the Earth’s mantle is mostly made from. Or so scientists suppose: nobody has yet taken a sample to prove it.
Perovskites are a family of minerals named after the Russian mineralogist Count Lev Perovski in 1839. They may prove to be the Holy Grail of superconductor research – a material that can conduct electricity without resistance at normal temperatures.
This would make a world of ‘floating’ trains and unimaginably fast computers a reality. At present, superconductors only function at unhelpfully low temperatures (the best so far recorded is –135 °C).
Apart from perovskite, it is thought that the mantle is made from magnesio-wusstite (a form of magnesium oxide also found in meteorites), and a small amount of shistovite (named after Lev Shistov, a graduate student at Moscow University, who synthesised a new high-pressure form of silicon oxide in his lab in 1959).
The earth’s mantle sits between the crust and the core. It is generally assumed to be solid, but some scientists believe
that it is actually a very slow-moving liquid.
How do we know any of this? Even the rocks spewed out of volcanoes have only come from the first 200 km (125 miles) below the surface and it’s 660 km (over 400 miles) before the lower mantle starts.
By sending pulses of seismic waves downwards and recording the resistance they encounter, both the density and the temperature of the Earth’s interior can be estimated.
This can then be matched to what we already know about the structure of minerals we do have samples of – from the crust and in meteorites – and what happens to these minerals under intense heat and high pressure.
But like much else in science, it’s really only a highly educated guess.
STEPHEN What is the commonest material in the world?
CLIVE Jim Davidson’s.
What does the Moon smell like?
Like gunpowder, apparently.
Only twelve people have walked on the moon, all of them American. Obviously, in their airtight space suits the astronauts could not actually smell the Moon, but moondust is clingy stuff, and plenty of it was traipsed back into the cabin when they returned from the Moon’s surface.
They reported that moondust feels like snow, smells like gunpowder, and doesn’t taste too bad. The dust is actually mostly made of silicon dioxide glass created by meteors slamming into the Moon’s surface. It also contains minerals like iron, calcium and magnesium.
NASA employs a small team to sniff every single piece of equipment which goes onto its space flights. This is to ensure that no items which could change the delicate balance of the climate of the International Space Station make it on to shuttles.