Fridge light last word
Readers who have trouble in checking their fridge lights can do a simple digital test. Use any digit on either hand and press the little button just inside the door. If the light goes out you know that the door turns out the light automatically when the door closes.
Nothing
Chris Elliott makes three errors in the letter about body mass index (BMI) (17 December 2005, p 22).
First, it is indeed counter-intuitive that BMI is a function of the square of height when humans are three-dimensional. However, BMI as a measure of healthy weight-for-height was not based on a model, but on actual mortality data and assessment of which relationship of height and weight was most associated with longevity. While there might be questions about how good that fit actually is, or whether it oversimplifies, it would not be right to discount it altogether simply on the grounds that it doesn’t seem to make sense. As John Lee says in his letter in the same issue, “the fact that a mechanism is not obvious at the time can never be used to negate a finding”.
Secondly, rowers and coxes are not just scaled versions of each other: a (tall) rower built like the ideal cox would be too scrawny to row the boat competitively, while a (short) cox built like a rower would be carrying a certain amount of dead weight for navigation and steering purposes.
Thirdly, on bringing “fairness” into a consideration of biological attributes: the BMI was arrived at by studying epidemiological data. On that basis, as for other scientific phenomena, it is difficult to see how its mere existence can be fair or unfair (which is not to say, of course, that the question of fairness might not arise in, for example, policy decisions based on it). One might as well say that evidence of the importance of the peacock’s tail in mating success was “unfair” to male peacocks with dowdy or ragged tails.
In any case, I take issue with the comment about BMI being “grossly unfair to tall people”. Implicit in this would seem to be the idea that a tall person with access to whatever food he wants might feel constrained from a corpulence he inclines to by a draconian reading of numbers. Compare this with the person suffering from starvation, who could not find the means to increase his BMI to the healthy range if a gun was pointed at his head. Which one really might feel more justified in bemoaning the “gross unfairness” of his lot?
Bird flu inaction
Why has it taken so long for governments worldwide to take the possible bird flu pandemic seriously (special supplement, 7 January)? Why did we wait until it started to lick at our shores? If our governmental bodies had taken action when the outbreak was young we would have been able to save lives and eradicate not only the illness, but also the cost.
You quote the World Bank as estimating $1.4 billion for the cost of fighting H5N1 flu (14 January, p 6). I believe that the rich countries in our global society had the money and power to stop this at the start, but did not. Therefore, we are to blame for the ever-increasing threat of bird flu. The rich countries should be more than prepared to foot the bill, and should not expect repayment.
From Peter Dunnill, University College London
A recent Swedish study suggests that mild bird flu infections in people may be common in Vietnam (14 January, p 7). Widespread comments that this is good news for the rest of the world could be misleading. There is evidence that the earlier, less-virulent forms of the H5N1 strain infected people in south-east Asia at least as far back as 1990.
Infection with progressively more virulent strains effectively immunises people, and could explain why those putting down tens of thousands of chickens to combat outbreaks have not shown severe symptoms, and why children who have not received such graded boosters have figured highly in fatalities. If the H5N1 virus reaches countries such as the UK, where there has been no prior bird flu contact, the pattern of infection may not be the same.
London, UK
From Bob Kahn, Avian Flu Action
The special supplement by Debora MacKenzie on the bird flu threat raises controversial issues in the section entitled “How to protect yourself and your family”.
The spread of influenza is going to be uneven. Whenever a particular area reaches the “tipping point” into high rates of infection, the local community will need to implement its own emergency procedures. Hopefully, central and local government and voluntary organisations can work together now to establish a “help-your-neighbour network” providing meaningful local advice and support.
It is certainly true that the virus “could circulate for many months, and the second or third waves might be worse than the first, as happened in 1918”. MacKenzie mentions the possibility of seeking early infection before the healthcare system is overwhelmed. As she says, this is a high-risk strategy. No doctor would dare recommend it, but if it was clear that the first wave was exceptionally mild, perhaps it might be justified, especially for healthcare, transport and public utility workers, those in the emergency services and teachers.
Abingdon, Oxfordshire, UK
From Daniel Spero
I have been worrying about a couple of apparently overlooked possible threats that could affect many households even if bird flu is not transmissible between humans. One problem is that a pet cat or dog may come across an infected wild bird (alive or dead) and would undoubtedly investigate it. Later the pet would come into close contact with its owners, who could then contract the illness.
There is also scope for people to come into contact with the faeces of wild birds when refilling or cleaning garden bird-feeders. This again may be a way of contracting the illness.
Thaxted, Essex, UK
Debora MacKenzie writes:
鈥� Cats can catch, transmit and die of the H5N1 flu, so in theory they could infect humans. But first they must catch the virus. To do that they must encounter infected birds, and as yet there are none in western Europe, the Americas or the Antipodes. The carriers of the virus would mostly be aquatic birds, ducks and maybe gulls, which are beyond the prowess of most house cats (though not all). The smaller prey that cats usually catch tend to die quickly of the virus. Most cats ignore carrion, and the virus should disappear as the carcass rots.
By the same token, most birds at feeders won’t be aquatic and would be unlikely to carry H5N1. Don’t handle sick-looking ones, though. Droppings from infected aquatic birds might pose more of a problem.
Sleight of Heim
I was extremely interested to see New 杏吧原创 carrying an article about Heim theory, especially as it seemed to promise so many exciting technological possibilities (7 January, p 24). How amazing would it be if we could travel to the stars in the near future, based on a theory of quantum gravity that was lurking in the mind of one dedicated but reclusive physicist for all those years.
However, your article points out that no one actually understands Heim theory. Heim is dead, and the team who are promoting his ideas sound more like archaeologists than physicists to me. But what of the particle mass formula? If a theory with no free parameters predicts masses to such excellent agreement, does it have to be correct? I don’t think so. By playing around with fractions, exponents and logarithms for half an hour, I came up with a formula that agrees with Heim’s value for the mass of a proton to 10 significant figures.
So, do I have my own secret theory of quantum gravity? Of course not. The point is that numerical agreements that come out of very complicated calculations are meaningless. From an information theoretic point of view, a 10-digit decimal has the same information content as 32 bits, so if you include enough factors of聽 鈭�2, 蟺 and so forth, you can doctor the answer to be anything you like. To be meaningful, a numerical agreement has to come from a theory which makes sense and which bases its calculations on a simple, natural, fundamental principle. As far as I can see, Heim theory has yet to show that is so.
From Rudi Van Nieuwenhove
After reading up on Heim theory (at ), I became convinced that Heim was a real genius. His formula for predicting the masses of the elementary particles is really very impressive.
I imagine that testing the anti-gravity effect would require rather powerful equipment, at the limit of present technology, to lift a 150-tonne spacecraft. But I do not understand why the effect cannot be demonstrated by using weaker magnetic fields and a lighter rotating ring. I didn’t read anything in your article about a minimum threshold field for the anti-gravity effect to occur, so why not try to lift just a few grams?
A table-top experiment might be sufficient, and as such an experiment would be relatively simple, it seems strange that the anti-gravity effect has not yet been observed. Could it be an indication that there is a flaw in Heim theory?
Halden, Norway
From Hedley Mellor
All the physicists devoting their energies to trying to unite quantum physics and relativity could be wasting their time. Before they concentrate on fine-tuning M theory, for example, they could at least make an attempt to understand Heim theory 鈥� a theory of everything that already exists.
Hitchin, Hertfordshire, UK
Catchy names count
It seems the debate about the status of Quaoar, 2003 UB313, 2003 EL61 and Sedna as planets or otherwise has been partially resolved (10 December 2005, p 34). The Space Shuffle card game by Playroom Entertainment involves placing the solar system’s planets in order. In addition to the well-known nine, I was surprised to discover Sedna. Presumably the makers of the game required an extra planet to make a round number, or for some similar reason.
It is interesting that Sedna was chosen, when 2003 UB313, for example, appears to have more going for it in the planet status contest, at least according to the “size matters” criterion. It just goes to show that if planet status is determined by general societal opinion, a catchy, memorable, pronounceable name is far more effective than a cold scientific label, and actual scientific considerations are largely irrelevant.
Resisting entropy
Eric Chaisson proposes that cosmic evolution is the universal driver of the development of our universe (7 January, p 36). But surely such evolution is driven by even more fundamental laws and principles. The second law of thermodynamics, for instance, determines the direction that the evolution of our universe takes.
Energised systems run down, their disorder (entropy) increases and their complexity reduces with the passage of time. When an isolated system appears to reverse this direction 鈥� as with “living” systems 鈥� the effect is temporary and always at the expense of neighbouring systems. The overall effect is always an increase in entropy.
Life occupies only an infinitesimally small portion of the universe, but somehow it managed to produce a method for steadily increasing its own complexity and thus resisting the natural direction of entropy. We call that method evolution and, although it appears simple in principle, evolution is incredibly complex in its detail.
We need to remember though, that while evolution can explain the development of life, it cannot yet explain how life began, let alone why it began.
From Tony Woodhouse
Chaisson seems to confuse Darwinian evolution (a change in the genetic composition of a population over successive generations, as a result of natural selection) with the more general notion of change.
He states that “life forms process more energy per unit mass than any star”. By what definition of energy can this possibly be true? He then seeks to demonstrate that all systems increase in complexity and order over time and states that “it is ‘free’ energy that drives order to emerge from chaos”. This sits uncomfortably with the second law of thermodynamics, which states that entropy (disorder) increases over time as the result of the dissipation of free energy.
Rugby, Warwickshire, UK
Hot ice and memory
In Zeeya Merali’s article on “hot ice”, she says that it might be present in nature (24/31 December 2005, p 38). She also points out that clouds seem to have a “memory” that could be explained by hot ice.
Is it remotely conceivable that this is also the explanation for the homeopathic effect discussed in the article “13 things that don’t make sense”? (19 March 2005, p 30).
Creator's message
So Stephen Hsu and Anthony Zee want to find a complex message from God encrypted in the cosmic microwave background radiation (24/31 December 2005, p 32). Here’s a simpler method.
Thanks to the WMAP spacecraft, we now know the age of the universe with an uncertainty of only 200 million years. Some day, using even more spectacular technology, we might know its age to the nearest million years, and eventually, perhaps, to one year. And then, why not a single day? If the date of the big bang turns out to be 25 December, Hsu and Zee will have their answer.
My money, however, is on 1 April.
From Edward McCain
I was under the impression that the late Douglas Adams had already supplied the last message of the creator: “We apologise for the inconvenience”.
Wholly satisfying, in my opinion.
Bogalusa, Louisiana, US
For the record
鈥� In “How a supervolcano covers a continent” (14 January, p 19) we failed to mention that the research described was originally published in the journal Geophysical Research Letters (DOI: 10.1029/2005GL024597).
鈥� In our article on clean-burn engines (14 January, p 26), the units on diesel emissions should have read “grams per brake horsepower-hour”, but the word “hour” was missing.
鈥� In the story on the plan to allow the oil industry to develop land in Alaska (21 January, p 7), we said the area involved was 200,000 hectares. In fact it is 158,000 hectares. And rather than the industry having “free rein” as we said, development will be subject to certain restrictions. Also, indigenous Alaskans are properly referred to as Alaska Natives, not Native Americans.