Letters: Too much dust
I am a little concerned at the data presented by John Gribbin regarding
the fall of ‘star-dust’. An annual fall of 5700 times 106 tonnes is suggested.
On the 5.1 times 1014 square metres of the Earth’s surface this works
out at 11.2 grammes per square metre per year. The weight of star-dust falling
on a small suburban garden, say 1000 square metres, at 11.2 kilograms, probably
exceeds the weight of chemical fertiliser applied per year to most such
gardens. In view of the magical properties of star-dust, are we fertilisers
wasting our time?
William Lonie Melrose, Roxburghshire
* * *
John Gribbin writes: The calculation is correct, but fortunately there
is no need to cover your garden with protective sheeting just now. As the
report on 26 March perhaps failed to make completely clear, this kind of
fall of star-dust occurs only during the break-up of a giant comet in the
inner Solar System – roughly once every 200 000 years. But the next one
could arrive at any time . . .
Letters: Clerks with PhDs
Martyn Kelly’s interesting piece on textbook publishing in Nigeria (Forum,
19 March) refers (distressingly) to his academic colleagues in that country
having greater administrative burdens than their British counterparts. I
had an academic job in a British university once, and one of the reasons
I left it was that I realised that I was going to have to spend 30 per cent
of the rest of my working life doing low-grade administrative tasks, most
of which would have been better, and more cheaply, done by a well-paid secretary.
I first detected the problem when I noticed one day that I was the only
person in a six-long queue for the photocopier who didn’t have a PhD, and
what I learnt as time went on was that the organisational culture of the
trained academics (I was there to teach on account of my record as a practitioner)
included an almost complete inability to distinguish between secretarial
work, administration and management. (I know there are penumbrae, but twilight
does not disprove the distinction between day and night.)
The result was an extensive misuse of the time of the highly trained,
highly educated, and highly intelligent people among whom I was working;
and any attempt at suggesting that things might be organised differently
was met with incomprehension. Enquiries to friends in other places indicated
that the university I was in was no worse in this respect than any other.
If I were in charge of giving out government money to universities,
one of the things I would want to know from each would be ‘What are you
doing to make sure that your clerical, secretarial, and administrative work
is done by clerks, secretaries and administrators, and not by academics?’
I would not accept the answer ‘We need more money to achieve this.’ Any
institution which could afford to have me and five PhDs queuing at a photocopier
was not seriously poor.
Donald Simpson Rochdale
Letters: New eugenics
Frances Culshaw (Letters, 19 March) should not be surprised at the
conflicting messages about undesirable personality characteristics. The
origin of this conflict lies in the politics of geneticists’ lobbying.
In the Depression years of the 1930s the eugenics movement campaigned
for sterilisation of ‘inferior’ people. This idea was sold to the politicians
as a method of solving social ills such as crime, illegitimacy, drunkenness,
etc. For the public, sterilisation was promoted through an obnoxious propaganda
campaign which used base instincts such as racism and hatred of social deviance
to get the message across.
In the depression years of the 1990s the eugenicists are campaigning
for genetic engineering in a broadly similar way. The appeal to politicians
is much as before, a snappy ‘solution’ to poverty, civil disorder, crime
and other social ills. For the public, a new element is the free market
and consumer ‘choice’. In a climate of growing unemployment, increasing
competition between individuals, and the collapse of the welfare state,
parents will be ‘free’ to choose those characteristics leading to their
childrens’ success in the pecking order.
As extroverts are by definition more visible in society, and so tend
to do well in material terms (salesmen earn more than poets), it is not
surprising that characteristics of introversion should now be presented
as symptoms of disease.
C. Mather Meersbrook, Sheffield
Letters: Cynical industry
In ‘Save The Planet plc’ (Comment, 19 March) there is some emphasis
on the ‘cynical’ profitability concerns raised by the chemical industry
over the Montreal Protocol. As a chemist in industrial research and development
– in lead/zinc metallurgy, not CFC production – I can say from experience
that the concern is very real.
It comes in two forms. First, if a company in a developed country has
to meet a new environmental requirement there is usually a cost associated
with it. The common method of recovering this cost is to raise the price
of the product, thereby passing the cost to the consumer. In many cases
this is not possible, however, as is the case in the metals business. In
a substantially free market the price reflects the lowest cost of production
of the commodity. Therefore, if a company has to wear a new cost without
a commensurate increase in price, and others do not, the new impact can
be disastrous for the company concerned.
Secondly, in the development of new technology there is an interesting
phenomenon which can be summed up by the phrase ‘whoever is first loses’.
The first company to implement new technology usually has to wear the cost
of the R&D, commissioning the new plant and the production problems
which usually occur when trying to run a new process. Firms which adopt
the same technology later are able to draw upon the experience gained, and
therefore their own costs can often be much lower.
I fully agree with the Montreal Protocol, and other similar environmental
regulations. However, without common standards there will be great difficulty
in getting companies to cooperate, especially if meeting the new standard
is a suicidal action to the company concerned. Negotiation and agreement
of these standards is clearly the responsibility of our politicians. Perhaps
they should get their act together too.
Eric Roche Booragul, New South Wales
Letters: Morphic relevance
Sheldrake’s theory does seem a little far-fetched but it is clearly
linked to a similar effect I have personally experienced. I was working
in a well-known research laboratory in this country on a project in which
I had no previous experimental expertise. I knew what I had to measure
to find the required parameters, the apparatus was all set up and I set
out to make the measurements. I had no preconceived idea as to the magnitude
of the result expected at all.
My first set of results were rubbish: they were inconsistent and made
no sense. I went away and read about the work which had been carried out
elsewhere and, you’ve guessed it, when I returned to make the measurements
the same day I got consistent results agreeing with the other work. I know
the apparatus had not been touched by anyone else in the meantime, and
that day has haunted me for fifteen years now.
What do I make of it? In my mind I am absolutely sure of what had happened
and my theory is very easily tested. If what I am implying is true, all
we need to see is recorded data taken before a theory has been worked out,
and then examine the results to see if the earlier recorded data is in accord
with the new theory.
For example, look at pre-Newtonian ideas on the trajectory of projectiles.
Early manuscripts report that projectiles followed nearly triangular paths:
a projectile went up into the air until its energy ran out, then fell to
earth vertically. You will see early religious tapestries showing just this,
arrows sticking straight up from the ground without the slightest hint of
a parabolic trajectory. These guys were not stupid; they would have stood
sideways on to an archer and seen the arrow’s trajectory from a distance.
What is going on? Would it not be a dirty trick if every time a Newton
or an Einstein comes along with a logical argument or theory ‘nature’ obliges
by falling into step with the great thinker. Did planets follow elliptical
paths before Kepler?
My apologies for remaining anonymous. I am a ‘professional researcher’
with a string of letters after my name. My employers would not like this
letter at all and jobs are hard to find nowadays.
Anon
Letters: Morphic relevance
I read Colin Tudge’s review of Seven Experiments That Could Change The
World (26 March) with dismay.
Tudge begins by telling us that morphic resonance ‘lies outside the
ken of conventional science’. Later he asserts that the ideas are testable
and therefore ‘firmly within the bounds of bona fide science’. Amazingly,
he fails to notice that these statements are contradictory.
Worse is to follow. To suggest that a vixen’s ability to control her
cubs by looking at them is evidence for a revolution in physics is ridiculous.
Did Tudge not even try to think of possible conventional explanations? The
most impressive example was the divided termite hill whose halves remained
coordinated. Very mysterious, until you realise that if termites have regular
cycles of behaviour (hardly unlikely) then the two halves might maintain
the illusion of coordination by independently maintaining those cycles.
I am also at a loss to understand why we should worry that coordination
ceased when the queen was killed. It would have been much more surprising
if the separated halves had maintained coordination after such a dramatic
event.
I think that none of the experiments Tudge describes could possibly
change the world, for they are too ill-controlled to prove anything. Nor
do I believe we should be grateful to Rupert Sheldrake for suggesting them.
It will do no good to let people think sloppy experiments and folklore can
provide hard evidence. More likely it will encourage cranks who believe
they have discovered secrets hitherto unknown to science and are immunised
against criticism by their lack of understanding of the need for experimental
controls.
Some good may yet come of this, though. Why don’t science teachers show
their pupils this review and challenge them to think of ways in which the
phenomena Tudge cites can be explained conventionally? Then they might suggest
designing better experiments that really could provide reliable evidence.
In this way they would promote the virtues of good scientific thought by
making an example of the bad.
Jeremy Henty Cambridge
Letters: Not so natural?
The Scottish Office view that recent seabird deaths are due to a ‘purely
natural disaster’ following ‘severe weather’ is simplistic and misses the
point (This Week, 5 March). Seabirds in the North Atlantic have always had
severe weather to contend with and are well adapted to cope with it. Most
of the birds found along the North Sea coast in this recent incident had
starved to death and clearly found food difficult to find.
The Royal Society for the Protection of Birds has long argued that fluctuations
in fish populations are poorly understood. We have strongly supported the
need for more extensive fishery research and have recommended that the broad
‘extent of the problem’ be assessed. Andrew Slorance is at odds with his
government’s action plan for biodiversity in suggesting that ‘we must conclude
that the seabird wreck is a purely natural disaster until we have evidence
to the contrary’.
This is a far from precautionary approach. The government must demonstrate
that fishery practices do not have an adverse effect on fish stocks and
the overall health of the marine ecosystem even in the absence of known
’cause and effect’.
Graham Wynne RSPB, Sandy, Bedfordshire
Letters: Going nuts
Tightening of screws and nuts causes elastic deformation of the components,
resulting in a sustained force holding them together. This force is roughly
proportional to the torque applied. Even if, as suggested in New 杏吧原创,
friction between the nut and the surface to be bolted is eliminated (which
in any case leaves the greater friction between male and female thread members),
spanners and torque wrenches will still be needed. A finger-tight nut –
as suggested in the article – would result in near-zero clamping pressure;
hardly a good way to seal a cylinder head, for instance, against the pressure
in the cylinders.
Gerry Harant Blackburn, Australia
Letters: Going nuts
My understanding of the modus operandi of a bolt is that as it is tightened
beyond a certain point (the point at which the flange of the bolt is in
firm contact with its seat) the bolt begins to stretch. Even if friction
at the seat is eliminated, a torque is required to provide the necessary
axial stretching force.
Why a Teflon bolt should spontaneously tighten (that is, stretch) rather
than loosen itself is a mystery to me – but not, however, as great a mystery
as why it should tighten itself ‘to the optimum holding tension’. Surely
this is more often than not a property of the bolted object, rather than
the bolt itself. Friction may hinder the tightening of a conventional bolt,
but it also ensures that the bolt does not undo itself.
I certainly do not relish the idea of a transatlantic flight in an aeroplane
held together by hand-tight ‘Supa-Nuts’.
Nicolas Lyons Newbury, Berkshire
Letters: Going nuts
Les Matthews’s nuts (Technology, 12 March) may have integral PTFE washers
to make tightening them easy – but this is also going to make them easy
to undo – prey, you might say, to vibration and vandals.
Compared with getting the nut on I would have thought that getting it
to stay on was of much greater importance – for a whole variety of safety-related
reasons. So, until someone comes up with a nut that slides on with finger
pressure, and can then successfully resist the loosening vibrations found
in so many mechanical applications – I remain unconvinced.
Tony Griffiths Buxton, Derbyshire
Letters: Flying scampi
The delights of Chinese maggot protein (Feedback, 26 March) are supported
by evidence that termites have as high a calorific value as rump steak,
and the habits of tribes whose favourite grub is that of a beetle or wasp.
Hundreds of insect species are used directly as nutritious food by those
who do not consider them as distasteful as most Westerners do.
A fascinating little book, complete with menu, Why not eat insects?,
originally published in 1885, has been reprinted by the National History
Museum; and in a lecture to the 10th British Pest Control Conference in
1992, entomologist Dick Vane-Wright suggested we consider locusts as ‘flying
scampi’, presumably on the basis ‘if you can’t beat ’em, eat ’em!’
What the idea needs, of course, is some professional marketing. Anyone
for an American Chocroach?
Peter Bateman East Grinstead, West Sussex
Letters: Too much dust
I refer to the interesting article by John Gribbin entitled ‘Fire from
the stars could spell global disaster’ (New 杏吧原创, Science, 26 March).
I am puzzled by how the dust flux figure of 5700 million tonnes per
year was obtained. This figure is the amount that is supposed to be intercepted
by the Earth following the break-up of a large comet in the inner Solar
System.
Currently, only 40 000 tonnes per year fall on the Earth, as determined
by Love and Brownlee after analysing the LDEF satellite and reported in
Science, 22 October 1993. This low value seems to be consistent with geochemical
evidence found in the ocean sediments and the relatively thin layer of interplanetary
dust accumulated by the lunar surface (about 70 millimetres) over the age
of the Solar System.
If the figure of 5700 million tonnes per year suggested in John Gribbin’s
article were to last for only 1000 years, at intervals of 200 000 years
as implied, then the amount of dust collected by the Earth and Moon would
be some 712 times greater than currently accepted. This would result in
a dust layer of 54 metres accumulating on the Moon’s surface and 108 metres
on the Earth over the lifetime of the Solar System.
These figures clearly contradict the observational evidence which is
better preserved on the lunar surface due to the lack of ‘geological’ processes.
G. Aucker Chelmsford, Essex
Letters: Is it a bird?
Q: My patio is well lit by the summer sun, which illuminates the floor
and the adjacent walls. Last year I noticed that when a bird flew overhead,
it cast a shadow on the patio. The bird was flying at the correct height
to just clear the wall on my right. Its shadow moved across the patio floor
at the same speed as the bird. However, when the shadow reached the base
of the wall, it accelerated instantly, climbing the wall before reaching
the top and continuing along the flat roof, again at the same speed as the
bird.
If the bird had been an object travelling at the speed of light, then
the shadow on the ground and the flat roof would have also been travelling
at the speed of light. But what of the period when the shadow was travelling
up the wall? Under this condition, the shadow would have had to travel faster
than the speed of light, which would present a direct challenge to Einstein.
Is there any other explanation?
A. R. Seabrook Eastbourne, East Sussex
Letters: Rising cold
Q: Heat is supposed to rise. Why, then, is it colder on top of a mountain
than in the valley below?
J. M. Allen Burley, Hampshire
Letters: Double vision
Q: I have a mirror made in about 1800. It produces a clear secondary
image above the main image, regardless of whether the object being reflected
is above, below or to the side of the direct line of sight. The displacement
is about 10 millimetres at 1 metre (slightly less towards the bottom of
the glass). The glass is about 6 millimetres thick and so could hardly produce
the effect by internal reflection even in one direction. Can anyone suggest
a reason for this effect?
Richard Hilken Exeter, Devon
Letters: Wear and where?
Q: Much is made of the problem of recycling the millions of used vehicle
tyres. But what has happened to all the rubber which used to be on these
tyres? If it is worn off as cars travel why don’t the roads slowly develop
an increasingly thick layer of tyre rubber? Rubber-coated roads would presumably
result in less tyre wear, but this does not seem to be the answer.
Ian Kellie Gloucester
Letters: Bedtime blues
Q: Why do I often experience a violent contraction – almost a convulsion
– of the limbs, particularly the legs, when just dozing off to sleep? This
can be sufficient to wake me up completely. I have also observed the same
thing in some pet animals.
S. T. Dobbs Market Harborough, Leics
Letters: Ask us another . . .
New 杏吧原创’s question and answer section is going strong. Answers
to the questions we have already published have been pouring into the office
along with more questions about scientific phenomena. We intend to begin
publishing readers’ answers in the issue of 7 May, when the column will
move to the inside back cover of the magazine, opposite Feedback. Here is
the latest batch of questions. Please keep providing us with both answers
and more questions. The senders of all answers that are printed will receive
a 拢10 book token.
Letters: God's razor
Colin Tudge’s article on Occam’s razor (Forum, 19 March) reminded me
that when I was studying biochemistry at Cambridge a number of lecturers
were constantly trying to impress upon us the fact that life was often more
complicated than you might think. A notorious exam question invited us to
discuss the contention that certain elegant experiments gave rise to conclusions
which were ‘neat, simple and wrong’.
Keith Tipton (later professor of biochemistry at Trinity College, Dublin)
expressed what could be a summary of Colin Tudge’s point most memorably,
in a line he attributed to Malcolm Dixon, the enzymologist, as: ‘God doesn’t
always shave with Occam’s razor.’
David Hall Reading
* * *
Correction: ‘Old tyres don’t die, they just dissolve away’ (Technology,
12 March) gave the impression that 250 million tonnes of tyres are scrapped
each year in the US. In fact this figure is the total number of tyres that
are currently in dumps, of which only a small percentage are recycled each
year.
Also, to protect a pond requires 100 grams of tea, not 100 milligrams
as stated in ‘Tea for Toads’ (Letters, 16 April).
Letters: Napoleon's organ?
Further to the correspondence on tin below 13.2 degree C and the legend
about the trouser buttons of Napoleon’s army (Letters, 12 February and 19
March), the organ-building fraternity can supply interesting information
and actual pictures of the ravages of the ‘tin disease’, as they called
it, in organ pipes in unheated churches in cold climates. When the pure
tin was scratched at very low temperatures, a spot of spontaneous conversion
could start and grow, looking like a boil on the skin; moreover, any of
the grey powder (the alpha form) falling on a clean tin surface would start
off another ‘boil’. The old story about the load of tin sent by rail to
Russia in winter that arrived as grey powder instead of ingots – and nearly
caused an international incident – is perfectly feasible and probably true.
Quite a different phenomenon but involving trouser buttons comes from
one of England’s long-wave radio transmitters. The output coupling coil
to the aerial was in the roof space – an all-wood construction, metal being
taboo as eddy current heating had already caused a fire in another transmitter.
A carpenter sent aloft to do repairs unfortunately had a ‘bachelor button’
on his trousers and had to beat a hasty retreat.
I have often wondered what dental fillings might do.
Ralph West Devillac, France