Face to face
I note with some trepidation references to on-line doctorates in which students have no personal contact with their supervisors (Review, 18 November 1995). I have supervised and examined a considerable number of PhD students over the past forty years, and am convinced that the role of a good supervisor must include several constructive meetings every year in the same room as the student.
This is essential to encourage and inspire them, and to impart real wisdom about life and overcoming obstacles. It is also essential in developing the student’s ability to form constructive human relationships, and express ideas briefly and clearly, both verbally and in writing.
Every researcher working on worthwhile problem has periods of frustration when they see that the path they are pursuing may need to be altered. During these periods the advice and encouragement of an older person who has been through such periods themselves is invaluable.
Pickled flies
Your readers may be interested in a systematic piece of research I conducted recently.
For the past few days I have been subjected to a plague of small flies in my bungalow. Sitting the other evening with a remnant of fresh orange juice and brandy in a glass on my side table, I noted one of the flies proceed down the inside of the glass and, when within a centimetre of the surface, fall into the liquor.
That evening, being further bothered by the pests in my kitchenette, I prepared an identical brew and placed it by my hob. Next to this I hung a proprietary sticky strip of flypaper.
The results over the first 24 hours were as follows: 18 in the brandy, 2 on the sticky strip. There was one fly, sex unknown, which still found me irresistible.
For those interested in the minutiae of fly behaviour I sat and observed for 10 minutes (much more interesting than Neighbours) and made the following observations. The fly circles the glass five or six times doing a recce, lands on the outside of the glass and climbs over. It then proceeds down the inside of the vessel, tasting it as it goes, pausing now and again as though to contemplate the wisdom of its actions, and at a point about a centimetre from the surface of the liquor it falls off, for reasons one can only speculate upon.
For the sake of completeness, it is worth noting that the orange juice was the product of more than one country, the brandy French and the glass British.
A further 24-hour test revealed a considerable change in the capture rate, the sticky strip markedly improving its position. However, the flies still expressed a preference for the brandy 鈥� 60 per cent at the last count.
Have any of your readers any useful observations, or suggestions for the use of pickled flies?
Clever man
I very much enjoyed your “Complete Scientific History of the Universe” (28 October). I had not realised that Charles Bonnet (1720-1793) coined the term evolution a full 20 years before his own birth!
Correction: The article “Placental protein makes parasites feel at home” (Science 16 December) should have mentioned Patrick Duffy, who contributed equally with Michal Fried to the research described. The US Army Medical Research Unit is in Kisumu, Kenya, not in Nairobi.
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Tragic ban
It is not only Indonesia that is contravening international conventions by refusing permission for scientific investigations in the Exclusive Economic Zone (This Week, 2 December 1995).
Earlier this year, I led a cruise as part of the World Ocean Circulation Experiment (WOCE) from the coast of Antarctica to Rio de Janeiro, Brazil. Though this was a British cruise on the British Antarctic Survey vessel RRS James Clark Ross, it included participants from Brazil and Germany. Despite strenuous efforts by the British authorities, Brazil refused us permission to complete the final 10 stations (out of 140) which fell within its 200-mile EEZ.
This is a tragedy for science, since the main point of this cruise was to complete a continent-to-continent synoptic section of oceanographic measurements across the Southern Ocean. Our Brazilian oceanographic colleagues were as dismayed as we were, since they too are full participants in WOCE. You may get a flavour of our disappointment from the newsletter we sent back to Britain at the time, which is accessible on .
It is important that scientists stand together to denounce nations that are impeding the progress of science by making it difficult to take measurements in their waters. These measurements have no commercial or military value, and the data will be freely available to all. WOCE is designed to help us to understand the ways in which the ocean transports heat around the globe 鈥� these are global climate issues in which all countries should take an interest. Let’s hope that Indonesia will relent and allow these cruises to take place.
The beginning again
The problem I raised in my letter (28 October 1995) is that cosmologists of the quantum kind are postulating that the Universe emerged without cause from a state of nothingness, yet are simultaneously attributing properties and potentialities to this state.
The problem is that this approach, of not having your cake and eating it too, is rationally insupportable and scientifically incoherent. Where there should be falsifiable argument we are given speculations, abstractions and artificial analogies 鈥� that is, at best, philosophy and, at worst, metaphysics, theology, mysticism and magic. It is not science but only its facade, its counterfeit. Science demands observational data and empirical evidence or, failing these, very precise and logically compelling a priori or mathematical proofs.
Paul Davies writes that he prefers “a deeper explanation 鈥� a more subtle concept” for the existence of the Universe (Letters 18 November 1995). I should be grateful if he told us exactly what these are and why he prefers them. If these explanations, these concepts, are scientific and rational we shall all benefit from this disclosure. If they are not scientific and rational, then the need for disclosure is absolute and imperative, for reasons on which Davies, as a physicist, will need no instruction from me.
There is indeed, as Davies says an “old problem” here, but it is not the old problem he thinks. The problem is the cogency and consistency of proffered explanations that are presented as scientific hypotheses but cannot be tested 鈥� of assumptions that do not necessarily follow. For example: The Universe is and has been expanding, therefore it was less expansive in the past and, therefore, it had a beginning as a infinitesimal point of infinite density, infinite temperature, and infinite pressure.
The problem is of arguments consisting of words rather than facts; of analogies that pretend to account for solutions but do not. Contrary to what Davies suggests, it does not follow from the proposition that “there is no meaning to the question: what lies north of the North Pole?” that it is pointless and illegitimate to ask: “what are the mechanics that govern the coming into existence of a Universe that did not exist?”
This is indeed an old problem, one of the oldest that has beset our species. What we should start to do is look for new and meaningful solutions, not old 鈥� or new 鈥� ways of avoiding them.
鈥� 鈥� 鈥�
Davies completely fails to answer the problems posed by Ralph Estling’s letter. Instead, he simply paraphrases the letter in a dismissive way (“Ralph Estling raised the old problem of what existed prior to the big bang”) and then just discusses the misleading paraphrase.
Estling’s letter was a logical analysis of the statement by Davies, made earlier in this correspondence, that “Quantum physics and the so-called inflationary Universe scenario give a plausible account of the initial conditions, that is, of how the expanding Universe originated from nothing” (Letters, 23 September 1995). In his reply, Davies demonstrates what Estling describes as the cosmologist “galloping off in all directions” leaving the reader nowhere. There are several instances of contradictory arguments.
In his earlier letter Davies answered a question about the compatibility of black holes and the big bang which started this correspondence. His explanation was based on the statement that: “The laws of gravity are symmetric in time”. In the current letter he writes: “Because the big bang is the origin of time, prior is meaningless”. However, if time did not exist before the big bang, the equations governing the big bang cannot be symmetric in time and the argument of Davies’ first letter is negated by his second.
To give another instance, Davies writes, “Given those laws of physics, then the coming-into-being of space, time and matter in the big bang can perhaps be explained”. In the next paragraph he says, “People still fall into the trap of assuming that the laws of physics existed before the big bang. That is not true.” As Ralph Estling says, the rest of us shout “Whoa” being unable to follow such abrupt changes of mind.
Paul Davies wants to have it both ways. The laws of physics explain the big bang but didn’t exist at the time. Gravitation is symmetrical with respect to time, but time ceases to exist at the origin. The Universe at the beginning was both nothing and everything. Schr枚dinger’s cat is both alive and dead. What has happened to the normal rules of logical thought 鈥� the common sense sought by Ken Wallace at the start of this correspondence?
The correspondence has shown the gulf between those readers who tend to believe that when a set of postulates leads to contradictory conclusions, the postulates must be wrong, and those writers who follow the New 杏吧原创 editorial line, that the understanding of the Universe resides in these contradictions.
鈥� 鈥� 鈥�
We have two ways of ordering events in time: past, present and future; before, after and simultaneous with one another.
Davies asserts that this method of ordering events is invalid “before” the big bang: “Because the big bang represents the origin of time itself, ‘prior’ is meaningless when applied in the normal, temporal sense”.
Having, in this context, thrown “prior” in its recognised sense, out of the front door, he smuggles it in through the back door by allowing that “鈥� one may still use the word prior in a logical or explanatory sense as something more fundamental”.
This has no meaning for me: in what way does “prior” used in a logical or explanatory sense differ from “prior” used in the usual sense? Apparently, the term is transformed and made legitimate in the context of the big bang by being, or referring to “something more fundamental”. Is it rude to ask: more fundamental than what?
No clean hands
How odd that in 1908 Ernest Rutherford readily accepted the prize money from Alfred Nobel, the inventor of dynamite and then eleven years later did not shake hands with Fritz Haber, just because Haber’s development of ammonia synthesis, which has saved millions of people from death by starvation, could also be used to make explosives (Letters, 9 December 1995).
I am sure I am not the only one in whose eyes Rutherford has fallen a few notches on the respect scale, and I wonder whether this was what P. G. Sussman intended by relating this anecdote. Haber was as much a scientist as Rutherford, and no more responsible for grenades than Rutherford was for the atomic bomb.
I feel the time has come to stop glorifying such tales of the past which fortify the myth of the ugly “German”. Rutherford’s action in this tale does not promote the myth of the fair “Englishman” (albeit naturalised) either.
Pushing down
The article “Breaking the Laws of Flight” (18 November 1995) makes a common error in describing the phenomenon of aerodynamic lift. It ascribes lift to the cross sectional shape of the aerofoil which causes the air flowing over the top to move faster than the air flowing beneath, presumably creating a pressure differential that resulted in lift.
This is incorrect. An aircraft flies by pushing air down. In level, unaccelerated flight the “push” downward (air mass flow rate 脳 downward velocity of the air) equals the weight of the aircraft. This experience is common to anyone who has flown a conventional aircraft and realises that at slower forward speeds the angle of attack must be increased over that of normal cruise speeds. This assures that the mass flow rate goes up to compensate for the decreased downward velocity of air.
The actual nature of the downwash is complex but does include wing-tip vortexes. These are occasionally manifested at air shows by aircraft equipped with wing-tip smoke generators which show a downward, spiralling flow of air.
If this concept is confusing, consider two facts: first, conventional aircraft, assuming proper fuel and lubrication systems, can fly upside down for extended periods of time. Second, some aerobatic aircraft have wings with symmetric aerofoil cross sections. If the article is correct, the latter should not be able to fly.
The real purpose of the aerofoil shape used in conventional aircraft is that it generally produces the optimum ratio of lift to drag.
Keep it wet
Our group has been interested in the care of historic properties for many years. Tam Dalyell should be glad to know that our research has shown that the tolerable relative humidity (RH) fluctuations (for textiles or anything else) can be calculated from considerations of an object’s material properties (Forum, 11 November 1995).
Air conditioning systems are one way to limit damage from high RH excursions. Humidifying systems are also necessary to prevent damage from low RH excursions that otherwise occur in cold climates when buildings are heated.
The absorption of water vapour by organic fibres is well known, and these properties must be taken into consideration in any approach to preservation.
Recently, we used the water absorption properties of cellulosic fibres to develop a strategy for buffering photographic materials during low temperature storage.
Genetic ignorance
Andy Coghlan’s report of the discussions about gene therapy trials (“Gene dream fades away”, 25 November 1995) draws attention to two issues. First, it seems that the scientific and medical communities may have been overoptimistic in moving from basic research to clinical trials. Second, there has been a healthy concern about the potential side effects of gene therapy.
We are interested in public perceptions of the new biotechnologies and have recently explored the ideas of undergraduates about gene screening and therapy, in the context of cystic fibrosis. Some of our findings reflect these two issues.
It appears that the public may have an overoptimistic idea of the current capabilities of gene technology. Only a quarter of a group of 135 arts-based students in their final year (who might represent the scientifically naive but otherwise well-educated public) understood that gene therapy involved the addition of functional genes. Others in this group thought, falsely, that techniques were already available for selectively excising faulty genes, or even removing, repairing and replacing genes.
More than a third thought that one treatment would be sufficient, whereas repeated treatments are usually needed. Two thirds imagined that the future children of a treated woman would be protected to some extent, even though in fact her eggs would not carry the added functional genes. We imagine that their understanding of the term “genetic” is extrapolated, incorrectly, to mean “permanent” and “inherited”.
A group of 280 final-year biology students were better informed, but even here more than half misunderstood the principle of gene therapy. As for perceptions of the safety of gene therapy, also raised in Coghlan’s article, more than a quarter of both groups of students thought that gene therapy would increase the risk of cancer.
So, even when the practical problems of gene therapy are overcome, the general public may still harbour unrealistic expectations and unnecessary fears about the application of genetic technologies.
Wandering trains
What is the point of installing global positioning system receivers in trains (Technology, 2 December)? GPS receivers are useful in aircraft because they record movements which might be in any of three dimensions. Trains already have speedometers. By integrating the output from the speedometer with respect to time, it is a simple matter to work out a train’s position, providing it is moving along a defined route and the starting point was recorded.
The consequences of privatising the railways may be unpredictable, but it seems much more likely that trains will come to a complete stop, rather than wander away from the tracks or take off into the sky.
No threshold
The letter from M. Tubiana et al (2 December 1995) epitomises the attitude of the nuclear establishment in France which, alone among members of the European Community, has continued to reject the nonthreshold model of radiation risk put forward by all the international regulatory authorities including the International Commission on Radiological Protection, and in Britain by the National Radiological Protection Board. Tubiana’s letter makes the extraordinary claim that: “No survey, including those on atomic bomb survivors, detects any effect for doses of less than 200 millisieverts in acute irradiation.” I’m afraid these French scientists are seriously misinformed.
In 1987 E. Radford published data that show exactly such an effect (“Recent evidence of radiation-induced cancer in the Japanese atomic bomb survivors”, Radiation and Health, edited by myself and Richard Southwood, John Wiley & Sons). It is quite clear from Radford’s figures that effects, including deaths from leukeamia and other cancers, have taken place among people exposed to less than 200 mSv, and that there is no threshold. In fact, as many as 77 per cent of deaths from cancers other than leukaemia occurred among people exposed to 160 mSv or less.
It is odd that French scientists do not refer to these data, as they were published eight years ago. It is also odd that the French Academy of Science continues to argue in favour of a threshold model for radiation risk. On the other hand, the French government insists that there is no risk whatsoever from its programme of underground nuclear tests in the Pacific, and for this claim to have any credibility you have to believe that there is a threshold below which radiation is harmless. While in-vitro laboratory studies of human and animal cells do appear to support a linear or less than linear response to radiation dose, the wide acceptance of a threshold dose below which radiation exposure has no more long-term effects than “a mild dose of flu” (Comment, 2 December 1995) has serious consequences for radiation protection. In any one individual, DNA repair may well function to produce a linear or threshold response. But if, as seems likely, the gradient of the response curve (or the threshold level) differs between individuals then the acceptance of a threshold effect becomes alarmingly nonsensical.
The current understanding of the pathogenic mechanisms in many diseases, including cancers, is that DNA repair mechanisms in some individuals are deficient. The adverse response to radiation stress in these individuals will occur at a lower threshold or rise more steeply with dose than in the population at large. It is at these highly susceptible individuals that radiation protection measures should be aimed.