Colourless
Q: Why is static on a colour television only black and white?
A: When enough of a TV signal is received to give a reasonable picture, there is, hidden within the information, a “colour burst” which tells the receiver that a colour signal is being transmitted. This is usually omitted when old monochrome films are shown so that the black and white and shades of grey are reproduced as clearly as possible.
The colour burst locks an oscillator in the receiver so that the colour signal, in the form of phase modulation, can be decoded. When a receiver is operated without an incoming signal, the input circuits are working at maximum gain (seeking to find what is not actually there).
So what we see is a combination of the noise of the cosmos plus the noise in the input stages of the receiver. But what is important is that there is no colour burst, the oscillator is not locked and so the spots are always monochrome.
Who shall have this?
The subtleties of rules governing sharing are fine and dandy in the lecture room (“Fair shares for all”, 17 June, and Letters, 15 July). At sea, things have to be different. On 25 May 1789, Captain Bligh and the rump of his crew of the Bounty, after a month adrift on the south seas in an open boat, caught a sea bird about the size of a small pigeon.
Bligh records: “I divided it, with its entrails, into eighteen portions and by a well-known method at sea of ‘Who shall have this?’ It was distributed with the allowance of bread and water for dinner.”
Bligh explains the procedure thus: “One person turns his back on the object that is to be divided; another then points separately to the portions, at each of them asking aloud, ‘Who shall have this?’ to which the first answers by naming somebody.”
Obviously, the person doing the splitting (who has nothing to do with the allocation of portions) would try to make the portions as near equitable as physically possible, but in the end there would be good bits (breasts, wings) and bad bits (claws, beaks).
This method not only establishes a random distribution of portions but, very importantly, does it in a way that is transparently fair. In queueing systems, it has long been known that a queue organised in order of “shortest processing time” will give a better average throughput than “first come first served”, but there is no way you can explain that to the ordinary queueing punter. Equally, I suspect a divorcing couple might be rather suspicious of a 20-step iterative process for the division of all the family assets.
The only flaw in, “Who shall have this?” is that it doesn’t take any account of individual tastes, though no doubt this could be built in.
Rash scientists
Herbert Macgregor states that the wearing of gloves proclaims to undergraduates and others that the wearer is a scientist (Forum, 24 June).
In my experience a scientist can easily be distinguished by the telltale eczema-like abrasions on the hand caused by the powder used in the gloves; and it is this that proclaims to one and all that this person is a scientist. Powder-free gloves do exist but are difficult to use, and solving this problem would be a worthy task for any budding Nobel laureate.
Letters to the Editor
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Good breeding
You state that the recent hatching of a golden conure (Aratinga guarouba) at Sorocaba Zoo, Brazil, was the first time this species has been bred in a zoo (This Week, 1 July). Though rare, both in the wild and in captivity, the golden conure has in fact frequently been bred in zoos since 1970, if not earlier. In 1992, the most recent year for which detailed statistics are available to me, a total of at least 24 were successfully reared in five zoos, in several of which breeding is now a regular yearly occurrence.
It is possible, though I cannot confirm this, that the reported breeding was the first in a Brazilian zoo 鈥� if so, this would be a significant landmark in the conservation of the species.
Tomorrow's ghosts
Recent correspondence has discussed the possibility that ghosts are hallucinations induced by psychotropic substances in the walls of old houses (Letters, 15 April and 8 July). I would like to suggest another possibility.
Reading the article “Faster than the speed of light” by Julian Brown (1 April) fascinated me. I grew up in the 1950s and 1960s when anything was possible. Space and time travel were all the rage. Men were going to the Moon and the future looked really fascinating. Many an evening was spent in the cafe or pub debating the possibilities of time and space travel.
Brown’s article states: “Raymond Chiao has been pioneering a range of experiments that probe the twilight zone of quantum mechanics 鈥� an alien world where ghostly particles can spontaneously appear and disappear, where objects can pass through solid walls and where everything seems to dance to a different tune.” He also says: “If light can travel faster than light, shouldn’t it be possible to send signals backwards in time, causing all sorts of mayhem?”
When these two statements are put together they bring to mind some intriguing thoughts. Quite simply, I wondered if anyone else had considered the possibility that maybe someone in the future is playing with sending signals, in the form of images of people, back to our time and before, creating “ghosts”. They appear and disappear at will, pass through solid walls, doors etc and do not conform to our rules; or, as Brown puts it, “they dance to a different tune”.
For many decades, even centuries, people have looked to the past regarding ghosts. Maybe we should look to the future. I hope this does not appear too naive, but I would be interested to hear if anyone else has thoughts on this.
Einstein in hiding
In response to the question asked by Christine Sutton about Einstein’s absence from the 1933 Solvay Conference (Forum, 8 July), the biography of Einstein by Jeremy Bernstein (Fontana) supplies the answer:
Namely, that Einstein had left Belgium under threat to his life from the Nazis for his “Jewish” scientific contribution; his flat had already been raided by the Gestapo in Berlin on the pretence that he was going to finance a Communist revolt. His papers had been publicly burnt in the square before the State Opera House in Berlin.
He had been in “hiding” at Le Coq-sur-Mer since the spring of 1933 and he was not impressed by the standards of security offered him; it caused much hilarity when Professor Frank found him there by asking the locals.
He arrived in Princeton on 17 October 1993 to join the Institute for Advanced Study as its first professor.
Hacker heroes
Tam Dalyell declares that “computer hacking is one of the evils of modern life 鈥�” and goes on, “computer systems are now so complex that it is almost impossible to check them for every flaw” (Forum, 8 July).
Computer hacking may, in fact, be the saving of us. A glance at what is being developed within the US military (particularly the Defense Counterproliferation Initiative against Weapons of Mass Destruction 鈥� which involves acquiring the capability, automatically and preemptively, to destroy any target, including underground targets, deemed by space-borne sensors to be “proliferative”) shows it to be wholly dependent on ever more complex computer systems.
Given that “worst case analysis” is one of the great motivating forces in military design and procurement, the possibility of hackers breaking into systems, coupled with the impossibility of checking for their presence, may save us from this crass new arms race, the financial, psychological and environmental costs of which would put the last one quite in the shade.
Most computer hackers seem to be boys in their late teens. Research from the Department of Education at the University of Chicago shows that there is greater variability in the range of “talent” exhibited by men than there is by women. Skill in hacking may be one of these extreme talents that are sex-linked. Might it also be an example of neoteny?
Uncommon sense?
The article “Obscure objects of desire” (24 June) raises a question that has troubled me, and I guess many others, for a long time: the big bang theory of the origin of the Universe and the theory of black holes do not seem to be compatible. How can an object with the mass of a Universe escape its own almost infinite gravity to explode from a point? And, if that is possible, then how can a mass collapse to a point?
Common sense 鈥� very dangerous to employ when dealing with relativistic and quantum phenomena I’ve noticed 鈥� would suggest that something is wrong. So, is there a new force or particle to be discovered that will allow this apparent contradiction or is something more exotic required? Does anyone have an explanation that can be understood by normal humans?
Finding fruit
As a regular, non-scientist reader of your magazine, I am constantly surprised at the cart-before-horse approach taken by zoologists. A fine example is in Georgina Ferry’s article on the evolution of big brains (New 杏吧原创, Science, 1 July): “Robert Barton argues that fruit eaters have bigger brains simply because they need good colour vision to find ripe fruit.”
It’s the other way round, isn’t it? If this lemur can see the ripe fruit, that’s what it goes for. Giraffes eat off the tops of trees because it is easier that way; spoonbills feed the way they do because 鈥� well, what else can you do with a mouth and neck like that?
The presumption of external and predetermined purpose bedevils science as well as religion, it seems.
Toss of a coin
No one has ever seen a perfect circle, or a dimensionless geometrical point, or an unbiased coin. So my faith that repeated tosses of an unbiased coin produce statistically predictable results (Forum, 1 July) is unshaken 鈥� though how the tossing process should be specified is problematic.
The Platonic ideal of the unbiased coin is a perfectly circular cylinder with perfectly plane ends, perfectly perpendicular to its length 鈥� which of course must be much less than its diameter. Imagine such a cylinder, or disc, machined with the best possible precision. It will approximate very well to the “ideal” but not exactly.
Imagine now that I attach a sticky object, of appreciable size and mass, to one side 鈥� a 5p coin stuck onto a disc similar to a 10p coin will do. Do you now expect the outcome of repeated tossing of the “doctored coin” to be statistically “correct”? No, of course not. So, going down a few orders of magnitude, the different embossed patterns of heads and tails (essential for starting cricket matches) themselves must create a tiny bias.
I spent much of my working life producing “randomisations” to allocate different experimental treatments to blocks of field crops. I used published tables and computer generators of random numbers 鈥� and (as a last resort) a favourite coin. This is non-legal tender, old and worn almost smooth (though “heads” is distinguishable from “tails”). So, with hindsight, I probably chose an unusually “good” coin for the purpose.
Ian Stewart’s analysis of The Sunday Times columnist Roger Anderson’s peculiar perception of probability theory omits one useful fact: the best strategy is to do the opposite of what Anderson implies. Anderson’s strategy for guessing the outcome of a coin toss would be to bet on the outcome that has happened least so far. Far better to bet on the outcome that has happened most. Either the coin is fair, in which case betting that way makes no difference, or it is biased, in which case the previous tosses tell us the direction of the bias, and we should bet that way.
With the National Lottery things aren’t so good, since the outcome depends on the selection of successive balls. So while you should choose numbers that have come up most in the past, whatever (small) bias exists only increases your chances of winning a little.
If you really want to gamble, a better strategy would be to put the money you would have bet on the lottery in a sock. At the end of a year of doing this, pick the company on the stock exchange with the lowest share price on that day and invest the contents of the sock in it.
If I choose a number x in the lottery, another number (say, y) is bound to come up. I have come to expect this and it does not bother me. If the following week I choose a different number z, Murphy et al have conclusively proved that x is more likely to occur than when I chose it. If it does I will be very depressed that I changed my number. Anderson is therefore correct to advise choosing the same numbers every week, but for the wrong reasons.
If Anderson had considered that the 50 per cent probability that a coin will come up heads becomes a different probability merely because of human perceptions, experience and observation, but then applied this to photons rather than coins, he would have been entirely within mainstream science.
An old friend of my parents used to give this advice for avoiding terrorist attacks on an aeroplane: carry a bomb 鈥� the chance of there being two separate bombs on board one plane is infinitesimal.
Microbiology rules
The former editor of New 杏吧原创, Bernard Dixon, in his article on the golden jubilee of the Society of General Microbiology (Forum, 1 July) may have found it sobering that microbiology departments are disappearing from universities, but the strength of the discipline has always been its impact on other areas of biology and medicine. Indeed, where would “today’s lopsided emphasis on molecular genetics” be without the exploitation of the physiology and genetics of that most mundane of microorganisms, Escherichia coli?
As long as new pathogens continue to emerge and biotechnology requires microbial factories to produce high value products, the discipline of microbiology will remain. I am not sure that it should be as distinctive and individualistic as Dixon seems to suggest. Clinical microbiologists must have a knowledge of mammalian physiology and immunology and biotechnologists should be well versed in biochemistry and genetics. Some of us even claim to apply molecular genetics to understanding how microorganisms work. Are we so different in our aims from those assembled in Cambridge 50 years ago?
Even in a school of biology we can teach and train microbiologists, and we would argue that they benefit from a broader education. If the discipline has disappeared from the Commonwealth Universities Yearbook, it still lives in our students, in their courses, in their degree titles and at the research bench.
Radio Rutherford
Arguments about who invented radio will continue as long as nationalism, lawyers and fuzzy definitions of radio persist (Letters, 10 June and 1 July).
We must give Marconi the credit for making wireless telegraphy practical and commercially successful. However, there is one associated point raised by a correspondent that I would like to clear up. Ernest Rutherford never worked on wireless telegraphy as a research student in New Zealand. This is a myth which has its origins in a suspect recollection of 1923 by a biology teacher in a Christchurch school. There is no evidence to support this. All records, including Rutherford’s own statements, show it to be false.
He initiated his celebrated work on wireless telegraphy in December 1895, after some two months of other research in England. On 22 February 1896, using the device he had developed in New Zealand to detect and quantify fast current transients, he detected a wireless signal over a distance of half a mile, after which feat he switched research fields. In September 1896, the British scientific community congratulated him on his world record for distance, which, unbeknownst to them, had in the meantime been surpassed by Marconi.
Rutherford never lost his interest in wireless and regularly taught courses connected with it. In Canada he experimented with signalling between trains and stations and later at the Cavendish he encouraged Appleton’s pioneering radio researches of the upper atmosphere.
To the ongoing discussion about the early history of radio, may I add the text of a notice I once saw by the side of a highway in rural Virginia? “From nearby Bear’s Den Mountain to the Catoctin Ridge, a distance of fourteen miles, Dr Mahlon Loomis, dentist, sent the first aerial wireless signals, 1866-73, using kites flown by copper wires. Loomis received a patent in 1872, and his company was chartered by Congress in 1873, but lack of capital frustrated his experiments, he died in 1886.”
This correspondence is now closed 鈥� Ed.
Killer trout
There is no shortage of pedants among the readership of New 杏吧原创, but just in case nobody has pointed this out already, there was an omission in your article about carp in Tasmania (This Week, 13 May). While the European carp (Cyprinus carpio) was clearly identified as an exotic menace, it was not made clear anywhere in the article that the brown trout (Salmo trutta) and rainbow trout (Salmo gairdneri) are also exotic. There are no indigenous salmonid fish in Australia.
The negative effect of carp on trout and native fish populations and waterways is indeed something to worry about, as the trout population is a major contributor to Tasmania’s economy 鈥� principally from holidaying anglers. But native fish have their own intrinsic and ecological worth too. Introduced trout are a direct predatory threat to native fish, and in some areas significant and diverse populations of native fish only occur in trout-free catchments.
Can't buy me love
Kurt Kleiner starts his article with the statement “tropical forests contain undiscovered drugs worth at least $147 billion” and goes on to support this figure with calculations using data from the pharmaceuticals industry (This Week, 8 July). The US scientists responsible for this research imply that governments and business, when made aware of their figures, will become more conservation-conscious, and that putting a price tag on forests will aid their preservation.
I disagree with this, and the underlying principles of their research anger me. Recently I have seen many parties attempt to give areas of the Earth an “environmental” cash price, with the rare, pristine, or most diverse habitats being the most highly valued.
Pricing the Earth is beneficial for litigation purposes after an accident like the Exxon Valdez oil spill, or for international disputes such as the one over fish stocks. But I believe that attaching monetary figures to an ecosystem only serves to bring that ecosystem into the developmental equations that govern business ventures.
Road builders would compare the “environmental price” of destroying woodland with the extra cost of diverting the motorway around it. If that piece of woodland is not special enough to command a high price, and the motorway wins, then the developers can buy out their consciences by investing the destroyed wood’s environmental value into some other “green” issue.
To give land a price denotes ownership, and to give the sum of its flora and fauna a price denotes ownership of that ecosystem. I think the principle of ownership is against the ideal of conservation. The jungle does not belong to any governments or investors, only to itself.
If environmental economists price the rainforest, then the inevitable forces of supply and demand will operate and that price will prove its destruction. This research has only given prices in terms of the worth of plant-derived pharmaceuticals to Western medicine. What price would you give the forest in terms of its capacity to maintain a stable atmosphere by fixing carbon dioxide and producing oxygen? Should there be a trade in air futures or breathing bonds?
Whatever the cost assigned to a habitat, you cannot buy one just the same somewhere else. Everything is unique and therefore priceless. The only way to preserve what is left of the Earth’s wonders is with a currency of concern, with an asset of spirit and to leave behind a legacy of love.