TURING TEST: Science and technology

1. Tin, atomic number 50, is one of seven metallic elements known to the ancients (the others were iron, lead, gold, silver, copper and mercury). Being familiar materials, they tend to have short names, regardless of language. In English, though, tin has the shortest.

2. Rutherfordium; named after Ernest, Lord Rutherford, who discovered the atomic nucleus. Rutherfordium, atomic number 104, is a manmade element with a half-life of 1.3 hours.

3. Yttrium, ytterbium, terbium and erbium, atomic numbers 39, 70, 65 and 68. The village is Ytterby, 20km north-east of Stockholm, which is the site of a former mine that yielded all four, and also several other so-called rare earth metals, much prized for their electronic properties.

4. 11: hydrogen, nitrogen, oxygen, fluorine, chlorine, helium, neon, argon, krypton, xenon and radon. The first five on the list were discovered early in the history of chemistry, in the decades just before and after 1800. The last five, known as noble gases because they are chemically unreactive, were discovered in the 1890s and 1900s. Helium, also a noble gas, was identified in 1868, by analysing the sun’s spectrum, 27 years before it was isolated on Earth.

5. The order of star classes, ranked by temperature, in the main sequence of the Hertzsprung-Russell diagram. Each letter in the mnemonic corresponds to a star class. O- and B-class stars are the hottest and shortest lived. M-class stars are red dwarfs, the coolest and longest lived. The sun is in the middle, in class G.

6. Ceres, the largest member of the asteroid belt between Mars and Jupiter. When found, it was classified as a planet, because it appeared to be a missing object predicted by the Titus-Bode law of orbital radii. The discovery of other asteroids put paid to that idea.

7. The Crab Nebula. This is the remnant of a supernova observed by Chinese astronomers in 1054 CE. It is also the first item in Charles Messier’s catalogue of nebulae (hence, M1), assembled in the 18th century. Messier was a comet-hunter and his catalogue was of objects that might have been mistaken for comets when observed through contemporary telescopes.

8. Argon. The first noble gas to be isolated, which was done in 1894 by William Ramsay who found that, after he had reacted nitrogen from the air with hot magnesium, a small amount of unreactive gas was left over.

9. DEOXY, as in deoxyribose nucleic acid. One of the chemical differences between RNA and DNA is that the sugar, ribose, which forms part of the former, has to lose an oxygen atom to form part of the latter.

10. Barnacles. He wrote four books about them between 1851 and 1854.

11. Blue. Really. It is not colourless. Vibration of its chemical bonds absorbs red light, leaving blue behind.

12. A quark. Quarks are fundamental particles that, because the interaction between them gets stronger as they separate, can never be isolated. Up and down quarks are the building blocks of protons and neutrons, and hence of atomic nuclei. The others are components of more exotic objects, produced in particle accelerators.

13. In the brain. In Greek, “sea horse” is “hippocampus”. Deep inside each hemisphere of the brain is a structure that early anatomists thought resembled this peculiar fish. They are involved in long-term memory formation.

14. In the pancreas. They are clusters of cells, named after the anatomist who discovered them, that secrete insulin. Type-1 diabetes is a result of the sufferer’s own immune system attacking them.

15. Francis Crick, in his paper with James Watson, describing the structure of DNA. He added the sentence at the last minute, though it stated the obvious, to make sure no one else claimed credit for realising the significance of DNA’s double-helical structure.

16. The presence of a nucleus. Eukaryotes are plants, animals and fungi (and also a lot of single-celled critters such as amoebae). Prokaryotes are bacteria and archaea, a bacteria-like group recognised as distinct in 1977.

17. Corundum, of which sapphire and ruby are gem varieties. The numbers are mineral hardness on the Mohs scale. A higher number can scratch a lower one. The scale goes up to 10, which is diamond.

18. Sagittarius. That is why the Milky Way is brightest there. A powerful radio source called Sagittarius A* is believed to be a supermassive black hole at the galaxy’s very centre.

19. The Andromeda nebula. This galaxy, M31 in Charles Messier’s catalogue, is 2.5 million light years away and clearly visible to the naked eye if the sky is cloudless and there is no light pollution. A second galaxy, the Triangulum nebula, M33, which is 3 million light years away, can sometimes be seen with the naked eye, too, but was originally discovered by telescope.

20. Celtic tribes that lived in Wales. Much of the geological time scale was worked out by British geologists, which also explains the Cambrian (from Cambria, the Roman name for Wales) and the Devonian (from the county of Devonshire).

21. Around 4.54 billion years old. An early calculation of about 6,000 years, based on Biblical data, turned out to be an underestimate. The modern figure uses rates of decay of radioactive elements to date meteorites that have remained unchanged since the beginning of the solar system, when Earth (the rocks of which have changed a lot) was formed.

22. Around 13.8 billion years old. This estimate is based on data collected by the Planck space observatory, which can see directly back to within 380,000 years of the beginning of time. Before this, space was opaque.

23. In a cell. It is a complex of membranes that acts as a finishing shop for proteins.

24. That the speed of light is invariant. This was the crucial discovery upon which the theory of relativity was built. If the speed of light cannot vary, then space and time have to vary instead, to accommodate that fact.

25. The Cretaceous, that is, the period immediately following the Jurassic. Odd. But true.

26. Brownian motion. This is the random movement of things like pollen grains suspended in water, which can be seen under a microscope. Einstein proved it was caused by water molecules hitting the pollen, thus showing that molecules (and hence atoms) are real, physical objects and not, as some thought at the time, mere abstractions.

27. They are the names of atomic orbitals. Electrons, being governed by quantum theory, are simultaneously waves and particles, and their precise position is always uncertain. They do not, therefore, orbit atomic nuclei in the way that planets orbit the sun. Rather, they are more or less likely to be found in a particular, often lobe-shaped, volume of space near the nucleus.

28. A neutron star, or pulsar. In 1992 it became the first star other than the sun to be confirmed as having planets orbiting it.

29. 60. Their arrangement is the same as that of the vertices of the polygons that make up a football.

30. Oxygen. All elements heavier than lithium (some of which, along with hydrogen and helium, was synthesised in the Big Bang) are entirely the product of atomic-fusion reactions inside stars or of stellar explosions called supernovae. Lighter elements are generally more abundant, but the details of these reactions conspire to favour oxygen.

31. In the atmosphere. It is a layer of ionised gas that reflects radio waves, meaning they can be detected over the horizon from where they are broadcast.

32. Ageing. The idea is that, since accident or disease will carry an organism off eventually, it is not worth evolution investing too heavily in bodily repair mechanisms, if those resources might better be deployed in reproduction. Hence the soma (ie, the body) is disposable.

33. Venera 7, a Soviet probe, which arrived on Venus in 1970.

34. Mercury. There is no particular known reason as to why this is so. It just is.

35. The Nobel Prize for Physiology or Medicine. In 1973, stretching the meaning of “physiology” to its limits, the Karolinska Institute in Stockholm awarded the prize to three pioneering animal behaviourists, Konrad Lorenz, Karl von Frisch and Nikolaas Tinbergen, who worked, respectively, on the three species concerned. Tinbergen’s brother, Jan, also won a Nobel prize. His, awarded in 1969, was for economics, the first for that discipline.

36. Aldabra, an atoll in the Indian Ocean. Their habitation of the place helped save it from being turned into a military base in the 1960s.

37. Ammonia, which, in turn, is made into fertiliser and explosives, and which helps explain why the 20th century saw both the greatest population growth in history, and the bloodiest wars.

38. Comets. This cloud, which surrounds the sun and is believed to stretch out for around a light year, contains frozen leftovers from the solar system’s beginning. Occasionally, one of these falls in towards the sun, developing a tail of gas and dust as it heats up on the way.

39. Asteroids that have the same orbit as Jupiter. The Greeks orbit 30 degrees in front of the planet and the Trojans 30 degrees behind it. These locations, called Lagrange points, are places where the combined gravities of Jupiter and the sun create a “well” from which objects, once inside, cannot easily escape.

40. Its reaction to a violet stain, which was discovered in the 19th century by Christian Gram, a Danish bacteriologist. Gram-positive bacteria retain the stain. Gram-negative ones do not. In general, Gram-negative bacteria are more resistant to antibiotics.

41. Polonium—named after her native land, Poland.

42. Mimicry. A Batesian mimic is an edible animal species that looks like a poisonous one, to fool predators into leaving it alone. A Mullerian mimic is a poisonous animal species that looks like another poisonous one, making it easier for predators to learn what to leave alone. And a Vavilovian mimic is a weed that looks like a crop, fooling farmers into leaving it alone.

43. A piece of natural glass created by molten rock splashed out by a meteorite strike. Most are found within one of four fields, each associated with a single strike, in Australasia, North America, Central Europe and the Ivory Coast.

44. A piece of tissue in which the cell membranes have disappeared, leaving a mass of cytoplasm with nuclei floating free in it. Many fungi are syncytia. And several viruses cause pathological syncytia to form.

45. The two arms of the molecule around a carbon-carbon double bond. Carbon atoms can bond to four neighbouring atoms, but in some circumstances they bond twice to the same atom, forming a double bond. Single bonds can rotate, but double bonds are rigid, helping define a molecule’s geometry. All fats have long chains of linked carbon atoms in them. In a cis fat, a double bond puts a kink in this chain. In a trans fat it does not.

46. The chance of there being intelligent, industrial life elsewhere in the galaxy. The equation has terms for the number of stars in the galaxy, the fraction with habitable planets, the likelihood of life emerging on a planet, and so on. Some terms have plausible numbers attached. Others do not. It was devised in 1961, by Frank Drake, an American astronomer.

47. A telescope. Specifically, one that always pointed at the sky’s zenith. Besides being an architect, Christopher Wren, who designed the monument, was also an astronomer.

48. It is the chemical cycle by which plants use energy derived from light to turn water and carbon dioxide into sugar and oxygen.

49. 1950. Establishing the age of an object often requires radioactive dating. For objects more recent than 1950 that is hard, because they may have been contaminated by radioactivity from bomb tests.

50. Isaac Newton, in an uncharacteristic (and probably calculated) bout of modesty.