For the record
鈥� Feedback mistakenly stated that West Broomfield is in New York state (18 January). It is, of course, in Michigan.
Test veteran
I am rather bemused by the numbers of British service personnel involved in nuclear explosions and tests during and after the Second World War, which you put at 25,000, and some of the inferences drawn in your article about nuclear test veterans (23 November 2002, p 14).
I can only speak with any authority on Nagasaki, Hiroshima and the two trials at Emu Field, South Australia, in 1953. The British team investigating the damage in Japan consisted of only 16 men and the US team was not a great deal larger. We were housed on American naval ships and not in the cities themselves. It is true we had no special “protection” when moving around, even at ground zero, but I never heard of any concerns among the team then or in later years. American troops never occupied the cities when we were there: there was nothing to occupy.
The first British trial after the war was a naval affair carried out at sea. The second and third were in the Australian desert interior at Emu Field, where the logistics could not have supported a large number; there was no drinking water, for example. Looking at my souvenirs, I collected the signatures of those involved 鈥� 10 Australians and 33 British staff, starting with Bill Penney who led the programme that developed Britain’s bomb. This was basically the total scientific team.
Penney would not allow anyone to watch the tests until the flash was over. Investigating the targets afterwards, I was kitted out in a rubber suit with a radiation detector which was monitored. I was decontaminated afterwards in the usual way.
Were the later trials completely different? I wonder whether the numbers quoted included the service personnel, mostly Australians, who built the test sites but had nothing to do with the tests themselves. Those that remained were given the opportunity to view the tests from a safe distance, if they wished to, but surely could not be classed as “test veterans”.
Incidentally, no one has ever approached me concerning my health.
Facade of science
I was saddened to see a journalist as respected as Fred Pearce resort to a smear in his defence of Bj酶rn Lomborg’s publication of his controversial book The Skeptical Environmentalist (18 January, p 23). If Pearce has citeable evidence that any of the four distinguished scientists who criticised Lomborg in Scientific American cherry-picked their data he should put it before us. The Danish committee that drew on those articles to pronounce Lomborg guilty of “scientific dishonesty” is clear and direct in stating that its judgement is based on the book’s claim to be scientific.
Lomborg is entitled to be in ignorance about the state of the environment, and I am by no means alone among environmentalists in welcoming every possible opportunity to attract public attention to these vital issues. What Lomborg is not entitled to do is to cloak his opinions on them in a facade of science and have that abuse go unchallenged.
Pearce is right to say that science is an adversarial process. But it is an adversarial process with rules. The Danish committee simply says that Lomborg broke those rules. That is a very long way from being a witch-hunt. If Lomborg wishes us to treat his opinions as having some basis in science, let him submit just one article on the environment to a peer-reviewed journal.
Rescuing the banana
You were right to report that the banana 鈥� a basic staple food for hundreds of millions of poor people in the tropics 鈥� is under threat from virulent pests and diseases (18 January, p 26). But the problem is not insurmountable.
In the past 10 years, some improved varieties suitable for large-scale production have been made available. The real obstacle to beating the many diseases that threaten the banana is that worldwide only five scientists are working to breed improved bananas 鈥� a meagre research effort decidedly out of proportion to the scale of the problem.
This is alarmingly little investment, given the banana’s global significance. It must be increased if the world’s most popular fruit is not to decline still further.
Letter
I read with interest the story of the Honduran Foundation of Agricultural Research hand pollinating, peeling and sieving 400 tonnes of bananas to find a few seeds, from which only one resistant plant was grown.
I wonder if they have considered planting wild bananas close to their crop and then offering a reward to anyone who finds a banana seed that results in a new breed of banana. Given that the 400 tonnes produced one viable plant, the 50 million tonnes of bananas grown commercially each year ought to produce 125,000 new banana plants.
This should not be difficult to implement. Marketing departments have for years been offering prizes to anyone who finds a potato crisp packet with a gold token in it, so why not for a banana with a seed?
Israel's nukes
Why did you not include Israel in your list of countries with nuclear weapons (11 January, p 17)?
Ian Sample writes:
鈥� While figures for Israel’s nuclear stockpile were not included in the data from the Natural Resources Defense Council on which we based our table, best estimates, such as the those produced by the Federation of American 杏吧原创s, suggest the country currently has between 100 and 200 nuclear warheads.
Inflamed arteries
Helen Phillips’s article is most welcome in highlighting what some of us in the field have been saying for years: that the cholesterol theory of atheromatous heart disease is inadequate (11 January, p 36).
But perhaps there was too much emphasis in the article on the idea that the inflammation is caused by infection. Moderate rises in levels of the amino acid homocysteine in the blood are common, and they correlate with coronary heart disease. This fits in nicely with the inflammation theory, since homocysteine damages the endothelium of blood vessels, which consequently becomes inflamed. No infection is involved.
Efforts are currently under way to discover whether folic acid supplements can help keep homocysteine at normal levels.
Gravity trapped
I was very interested to read the account by Ed Fomalont and Sergei Kopeikin of their work on the measurement of the speed of propagation of gravity (11 January, p 32).
If their results can be verified, it would seem that gravity does indeed obey the fundamental laws of the Universe. However, this gives rise to the question: how does gravity then escape from a black hole?
The escape velocity within the event horizon is greater than that of light (and, it would appear, gravity). This ought therefore to make it impossible to detect a black hole by its gravitational effects on other bodies. Moreover, it would surely be impossible for a black hole to “grow” any further once an event horizon had been produced.
Is there any way out of this paradox?
Eugenie Samuel writes:
鈥� It would indeed be a paradox if gravity could escape from a black hole. But it can’t! The gravitational field around a black hole is actually that of the collapsing star a split second before the black hole formed. Read more at math. ucr.edu/home/baez/physics/Relativity/BlackHoles/black_gravity.html.
Fission facts
In weighing up the pros and cons of nuclear power, David Sang should have made a finer adjustment to his scales (Inside Science, 18 January). I noted several errors.
First, there is no evidence that “9000 extra deaths from cancer” have occurred in the people near Chernobyl as a result of the accident in 1986. Very few deaths have occurred as a result of increased radiation.
Although Magnox and PWR reactors operate at a temperature “only a little above 300 掳C”, and have a thermal efficiency of “around 30 per cent” (actually 26 per cent for Magnox and 35 per cent for PWR), advanced gas-cooled (AGR) reactors operate at 640 掳C and have an efficiency of around 40 per cent, comparable to a modern coal-fired power station.
MOX fuel does not consist of “96 per cent uranium, 3 per cent high-level waste and 1 per cent plutonium”. That is the composition of used fuel. MOX fuel consists of around 97 per cent uranium oxide and 3 per cent plutonium oxide.
Technetium-99 was discharged from Sellafield, not because of “a breakdown” in procedures, but by authority. Even so, steps are being taken to eliminate this relatively harmless discharge. Discharges from Sellafield are now a minute fraction of what they were decades ago.
The allegation that a North Korean nuclear plant “is capable of producing plutonium” should be seen in the context that every nuclear reactor produces plutonium, although special procedures are required to produce weapons-grade plutonium.
Finally, it is unclear why Sang included a comment on nuclear fusion (undeveloped) and not fast reactors (developed).
Space junk
I own a salvage yard and try and do my bit to find new uses for old and discarded objects. I know that NASA will probably break their back teeth trying to say this word and probably don’t even know what it means, but let’s give it a go boys. The word is: recycle.
Has nobody thought of gathering up all the space junk (18 January, p 13) and directing it into close orbit with the International Space Station? Once in place it could be used as a shield to protect this precious project from cosmic rays and collisions with meteors and dust that could result in catastrophic failure leading to loss of human life.
It could also be scavenged for spare parts and raw materials. Have you ever tried to get your hands on a 5-millimetre nut or a sheet of aluminium when you need it in outer space? I wish I owned that cosmic junkyard, yes sir!
Learning language
The idea that languages evolved to adapt to children’s limited cognitive abilities may make sense if the only language you are familiar with is English (18 January, p 30). English has virtually no inflections, and is extremely easy to learn informally. But the same cannot be said for other languages.
Czech, for example, has seven cases, three genders and various different forms of declension for each of these alternatives. To use a simple preposition such as “in”, a Czech speaker needs to know what case this preposition takes, the gender and declension of both the noun and adjective it refers to, and the ending that these both take, given all these variables. None of this is intuitive, logical or necessary.
It is not clear how any of this survived the need to be learned by children, nor that it has evolved to be simple. You report Morten Christiansen’s argument that children’s limited perceptions and memory “force them to focus on the basic ‘building blocks’ for further language learning”. But to learn a language like Czech one needs an attention to detail, not an overview.
In Czech, many words change form completely, depending on their position in the sentence. A general idea that, for example, pes means dog does not help much when the child needs to talk about three dogs (psy), five dogs (psu), or beside the dogs (psech).
If words typically used by children were easier to learn or more regular, this would at least suggest some kind of pressure on the structure of the language coming from children. However, in Czech at least, the words for kittens and puppies are irregular and even harder.