Great Mythconceptions Read online

  Of course, this is only a rough reading, but it does give you some kind of effective warning.

  References

  Holper, Paul N., Wow! Amazing Science Facts and Trivia, ABC Books, Sydney, Australia, p. 75.

  Vondeling, John, Physics, A World View, Saunders College Publishing, USA, p. 222.

  Walker, Jearl, The Flying Circus of Physics, John Wiley & Sons Inc., USA, p. 51.

  Eclipse Blindness

  A solar eclipse occurs when the Moon passes between the Earth and the Sun. In a total eclipse, the Moon blocks out all of the sunlight, creating an eerie deep twilight. Suddenly, in the middle of the day, you can see the stars. But many people, when given the chance, never enjoy the free cosmic thrill of a total solar eclipse, because they believe the myth that looking at a solar eclipse, or even being outdoors when it happens, will make you go blind. In fact, a total eclipse of the Sun can be pretty harmless.

  A partial eclipse, however, is far more dangerous. In a partial eclipse, the Moon blocks only some of the sunlight. (Actually, if you were not aware of the eclipse, you would probably think that a cloud was just temporarily covering the Sun.) But even if 99% of the Sun is covered, the tiny crescent of Sun remaining is bright enough to blind you, if you stare at it for anything longer than the briefest moment.

  The Sun does not emit new and strange forms of damaging radiation during an eclipse but continues to squirt out what it always has. You can certainly damage your eyes by staring at the Sun when it is partially covered by the Moon, because it is still emitting enough energy to damage you. You have to remove about 99.9968% of the Sun’s energy to make it safe to look at.

  The Sun gives out heat energy as well as light. The heat energy is focused and concentrated onto the central part of your retina, which deals with fine vision. If you stare at the Sun for long enough, you will lose your central vision. The Sun’s energy will burn out the central part of the retina. In extreme cases, the tissue will literally cook. You usually won’t notice this happening, because there are no pain receptors in the eye. Because your peripheral vision will not be affected, you will still be able to see out of the corner of your eye. But if you try to read fine print, it will be fuzzy, like reading through a metre of seawater, or a glass smeared with petroleum jelly.

  The US Army documented a partial solar eclipse causing blindness on 4 February 1962, with military personnel in Hawaii. The partial eclipse had enough energy in the exposed sliver of Sun to burn out the centres of the soldiers’ retinas, when they looked at the Sun. Over the next few days, many of the soldiers had trouble shooting accurately on the rifle range. Their vision had dropped from 20/20 to 20/200 — 10 times worse than normal. Most recovered, but some had permanent loss of visual sharpness.

  When the next total eclipse of the Sun rolls around, just remember a few rules:

  Observing the totally-eclipsed Sun with the naked eye is fine — but only when the Sun is totally covered by the Moon. You have to pick the moment, when there is no direct solar radiation to damage the eye.

  Never look at the partially-eclipsed Sun with the naked eye. Even a slim crescent of Sun has enough energy to blind you.

  It is safe to look at the fully-exposed or partially-exposed Sun using approved filters, such as professional Solar Viewing Mylar filters. Never look directly at the Sun through smoked glass, exposed photographic film, magnetic discs ripped out of old floppy discs, CDs, or Mylar food packaging.

  The pinhole camera method is another safe way to view an eclipse in action. Punch a two-millimetre hole into a piece of card and, with your back to the Sun, hold the card so that the Sun’s light passes through the hole and onto another card which acts as a screen. The image of the Sun will be slightly fuzzy but you will be able to see the shape of the eclipsed Sun.

  As long as you don’t look directly at the Sun, it is perfectly safe to be outdoors as the Sun drifts in or out of the eclipse.

  It is also perfectly safe to look at the totally-eclipsed Sun. This is because the Moon, which is 400 times smaller than the Sun, is also 400 times closer — so it can totally obscure all direct light from the bright part of the Sun. In this brief window of totality, it is safe to abandon the pinhole camera briefly, and gaze up in awe at the total eclipse of the Sun, complete with the shimmering corona, and all its associated splendours.

  How Dark is Safe?

  If you look at the Sun with the naked eye, you will burn out the centre of the retina. If you look at it through a brick wall, no light will reach your retina and this will be perfectly safe.

  Somewhere between ‘no protection’ and the ‘brick wall’, is a safe level. For the case of the visible and infrared light coming from the Sun, the safe level is provided by a filter (Shade 12) that lets through 0.0032% of the light. But this is still a little bright for most people, so a darker filter (Shade 14) that transmits 0.0003% of light is more comfortable.

  References

  Harrington, Philip S., Eclipse!: The what, where, when, why and how guide to watching solar and lunar eclipses, John Wiley & Sons Inc., USA, 1997, pp. 2–3, 129–131, 205–208.

  Chou, Ralph, ‘Solar filter safety’, Sky & Telescope, February 1998, pp. 36–40.

  Anaesthetic Bomb

  The ‘make-them-unconscious’ Anaesthetic Bomb has been appearing in movies for over half a century. Because movie ‘good guys’ never kill anybody, they pull out the Anaesthetic Bomb, and roll or slide it towards people, who immediately fall to the floor unconscious. The Anaesthetic Bomb was used in the 2002 remake of Ocean’s Eleven — and you can be sure that it will appear in future movies.

  The Anaesthetic Bomb has (according to legend) been used in house robberies by the villains who can then make their way through a house of sleeping residents without waking them. And of course, its use has been proposed in commercial jetliners as a way to harmlessly subdue violent passengers or terrorists.

  The Anaesthetic Bomb is not designed to affect just a region (e.g. regional anaesthesia for a leg) or a small patch (e.g. local anaesthesia for torn skin). No, in the movies, the bomb needs to give general anaesthesia instantaneously, making the person unconscious instead. A person under general anaesthesia is unaware of their environment, cannot feel pain, cannot move and has no memory of what happens during the anaesthesia.

  General anaesthesia took a long time to invent. In the Odyssey, Homer wrote about an Egyptian herbal drink called napenthe (probably either opium or cannabis) which eased grief and banished sorrow. In 1799, the English chemist Sir Humphry Davy, discovered that laughing gas (nitrous oxide) could relieve the pain of his infected tooth — but his claim was ignored. By 1842, an American surgeon Crawford Long, had started using ether as an anaesthetic, but he did not publish his results until 1849. Therefore the first use of true surgical anaesthesia is usually attributed to William Morton, an American dentist who, in October 1846, administered ether to a patient having a neck tumour removed at the Massachusetts General Hospital in Boston.

  In the early days of anaesthesia, usually only one drug was given. But today, several drugs are given at the same time to achieve many different aims (such as unconsciousness, muscle relaxation, loss of memory, paralysis and immobility). However, because these drugs travel via the blood to the brain, they can affect other organs in the body along the way. For this reason the anaesthetist has to monitor very closely the patient’s heart rate and rhythm, blood pressure, breathing rate and oxygen level in the blood.

  There is a very fine line between being conscious, being in a state of general anaesthesia, and being dead.

  It is very difficult to render someone unconscious without injuring or killing them. Doctors have to study medicine for five years or more, and then spend several years in general hospital training. To become an anaesthetist, a further four years of study is required.

  If safe and effective Anaesthetic Bombs really did exist, life would be easy for anaesthetists. They wouldn’t have to spend over a decade studying — all they would need to know is
to be out of the room when the bomb goes off.

  Moscow Anaesthetic

  Bomb

  On Wednesday, 23 October 2002, over 800 people were watching Nord Ost, a classic Russian musical in the Moscow Musical Theatre. Suddenly, over 50 Chechen militants, armed with machine guns, rushed in, held the audience hostage, and laid explosives inside the theatre and at all the exits. They then demanded that Russia withdraw its army from Chechnya, or else they would kill the hostages.

  Just before dawn on Saturday, 26 October, Olga, a 21-year-old survivor, saw billowing clouds of a grey gas drift into the theatre. She covered her face with her scarf and dropped to the floor — and was one of the few hostages who did not lose consciousness. Almost immediately, Russian soldiers stormed the theatre, shooting the Chechens.

  Even two days after the rescue, two-thirds of the surviving hostages were in hospital in a serious condition. About 117 hostages died from the effects of the still-unknown anaesthetic gas.

  References

  Schiermeier, Quirin, ‘Hostage deaths put gas weapons in spotlight’, Nature, vol. 420, 7 November 2002, p. 7.

  Rieder, Josef, et. al., ‘Moscow theatre siege and anaesthetic drugs’, The Lancet, vol. 361, 29 March 2003, p. 1131.

  Everest Not Tallest Mountain

  Most Australian school students are taught that the highest point on Earth is the tip of Mt Everest and that Mt Kosciusko is the highest mountain in Australia. But most school students have been misled.

  So what is the story on Mt Kosciusko? It is indeed the highest mountain (at 2228 m) on the Australian mainland.

  But the highest recognised Australian mountains are in the Australian Antarctic Territory — Mt McClintock (eastern sector — 3490 m) and Mt Menzies (western sector — 3355 m). However, the highest mountain on Australian Sovereign Territory is Mt Mawson (2745 m) in the Big Ben mountain complex on Heard Island in the Southern Indian Ocean, about 4000 km southwest of Perth. So while Kosciusko does have the distinction of being the highest mountain on the Australian mainland, it isn’t the highest mountain on Australian territory.

  And we do have volcanoes.

  Australia doesn’t have the technology to monitor the volcanic activity of weather-bound and remote Heard Island, but there were some very spectacular eruptions on Big Ben in February 2001.

  What about Mt Everest? Is it the highest mountain in the world? It all depends on what you mean by ‘highest’. Does it mean the ‘highest above sea level’, or does it mean that it ‘pokes out most into space and is furthest from the centre of the Earth’?

  Back in the 17th and 18th centuries, it was thought that a certain Mt Chimborazo, an extinct snow-capped volcano in Ecuador, was the highest point on Earth, at 6310 m above sea level. In 1852, the Great Trigonometrical Survey of India noted that a certain mountain named Peak XV was the highest at 8840 m. The British named it Everest in 1865, after Sir George Everest, who was the British Surveyor General from 1830–1843. It did not seem to matter that the local Tibetans and Nepalese had already given the mountain some perfectly good names — Chomolungma or ‘Mother Goddess of the Land’ by the Tibetans, and Sagarmatha by the Nepalese. Indeed, Everest himself thought that the mountain should keep its local name — but he obviously didn’t protest too loudly.

  The height of Mt Everest was adjusted to 8848 m in 1955, and then to 8850 m in 1999, after a team of climbers used state-of-the-art satellite measuring devices on the summit. All of these heights are measured above sea level.

  The reason that Mt Everest is not the highest point on Earth is that the Earth spins — and this spin makes the whole planet bulge outwards at the equator. The diameter of the Earth through the equator is about 21 km more than the diameter of the Earth measured through the North and South Poles.

  Let’s look again at Mt Chimborazo, which was once thought to be the highest mountain on Earth. It was first climbed by Edward Whymper in 1880.

  Mt Chimborazo is about 1.5º south of the equator, while Mt Everest is much further around the curve of the Earth at 28º north. So although Mt Chimborazo is about 2540 m closer to sea level than Mt Everest, it is about 2202 m further away from the centre of the Earth. It pokes further into space than Mt Everest. If this were better known, perhaps the achievements of the Conqueror of Chimborazo, Edward Whymper, would have made more of a bang. (In fact, three other peaks — Huascaran, Cotopaxi and Kilimanjaro — are also ‘higher’ than Mt Everest.)

  However, Mt Everest is still the highest mountain above sea level. By the end of 2001, some 1314 people had reached its summit, and 167 people had died trying. If you have US$65000, and are physically fit, you can try to reach the peak. But if you don’t have that kind of money to spend, you can console yourself with the knowledge that they are all climbing the wrong mountain anyway. On the other hand, Mt Everest is growing about 5–10 mm each year as the Indian land mass rams into Asia, pushing Tibet higher. So all that wealthy people have to do is wait another half-million years for Everest to be the highest mountain on Earth, under all definitions …

  High History

  After Mt Chimborazo, the title of ‘highest mountain in the world’ was handed to the Himalayan peak Dhaulagiri (8172 m) in 1809, and then to Mt Kanchenjunga (8598 m) in 1840.

  Mt Everest was first climbed on 29 May 1953, by Edmund Hillary of New Zealand and the local Sherpa mountaineer Tenzing Norgay. Neither has ever admitted who was technically the first to reach the peak.

  Heard Island (which has the highest mountain on Australian Sovereign Territory) was discovered by a British sealing vessel in 1833. It was later named for Captain John J. Heard, an American mariner. In 1947, control of Heard Island was transferred from the British to the Australian government.

  References

  ‘2 of British team conquer Everest — highest peak won’, New York Times, 2 June 1953, p.1.

  ‘Ask us’, National Geographic, January 2002.

  Kiernan, Kevin, Fitch, Stu & McConnell, Anne, ‘Big Ben: the fire beneath the ice’, Australian Antarctic Magazine, Spring 2001, pp. 4–5.

  Pott, Auriol, ‘A friend told me that Mt Everest isn’t the highest point on Earth. Is she right?’, Focus, December 2000, p. 34.

  Lemmings Suicide

  One myth deeply entrenched in our language is that of the ‘lemming suicide plunge’ — where lemmings, apparently overcome by deep-rooted impulses, deliberately run over a cliff in their millions, to be dashed to their deaths on the rocks below, or to drown in the raging ocean. Indeed, this myth is now a metaphor for the behaviour of crowds of people who foolishly follow each other, lemming-like, to their inevitable doom. This particular myth began with a Disney movie.

  Lemmings are rodents. Rodents have been around for about 57 million years and today make up about half of all the individual mammals on Earth. There are four genera of lemmings — Collared Lemmings, True (or Norway or Norwegian) Lemmings, Wood or Red-Backed Lemmings and Bog Lemmings. They are found in the cooler northern parts of Eurasia and North America. The True Lemming (which has the most impressive migrations) is about 10 cm long, with short legs and a short tail.

  Many rodent species have strange population explosions. One such event occurred in the Central Valley of California in 1926–27 with the mouse population reaching around 200 000 per hectare (about 20 mice per square metre). In France between 1790 and 1935, there were at least 20 mouse plagues. But lemmings have the most regular fluctuations — these population explosions happen every three or four years. The numbers rocket up, and then drop almost to extinction. Even after three-quarters of a century of intensive research, we do not fully understand why their populations fluctuate so much. Various factors — change in food availability, climate, density of predators, stress of overcrowding, infectious diseases, snow conditions and sunspots — have been proposed, but none completely explain what is going on.

  In the 1530s, the geographer Zeigler of Strasbourg, tried to explain these variations in populations by saying that lemmings fell out of the sky in stormy wea
ther, and then suffered mass extinctions with the sprouting of the grasses in spring. In the 19th century, the naturalist Edward Nelson wrote that ‘the Norton Sound Eskimo have an odd superstition that the White Lemming lives in the land beyond the stars and that it sometimes comes down to the earth, descending in a spiral course during snowstorms. I have known old men to insist that they had seen them coming down. Mr Murdoch records this same belief as existing among the Point Barrow Eskimo.’ But none of the Inuit (Canadian Eskimo) stories mention the ‘suicide leaps off cliffs’.

  When these population explosions happen, the lemmings migrate away from the denser centres. The migrations begin slowly and erratically, evolving from small numbers moving at night, to larger groups in the daytime. The most dramatic movements happen with the True Lemmings. Even so, they do not form a continuous mass, but instead travel in groups with gaps of 10 minutes or more between them. They tend to follow roads and paths. Lemmings avoid water, and will usually scout around for a land crossing. But if they have to, they will swim. Their swimming ability is such that they can cross a 200-m body of water on a calm night, but most will drown on a windy night.

  So there is a tiny kernel of truth in this myth. Lemmings have regular and wild fluctuations in population numbers — and when the numbers are high, the lemmings do migrate.

  The myth of mass lemming suicide began when the Walt Disney nature documentary, White Wilderness was released in 1958. It was filmed in Alberta, Canada, far from the sea in a region not native to lemmings. So the film makers imported Collared Lemmings, by buying them from Inuit children. They filmed the migration sequence by placing the lemmings on a spinning turntable covered with snow, and then shooting it from many different angles. The cliff-death-plunge sequence was done by herding the lemmings over a small cliff into a river. It’s easy to understand why the film makers did this. For one thing, wild animals are notoriously uncooperative. For another, a ‘migration-of-doom’ followed by a ‘cliff-of-death’ sequence is far more dramatic to show than the lemmings’ self-implemented population-density management plan.