Letter: Flippin Frisbee
Mace Schuurmans’s spendid article about Frisbees (‘Flight of the Frisbee’,
28 July) omitted one particular mode of flight. In the early 1970s, we underworked
flying instructors at RAF Little Rissington found that a Frisbee worked
superbly in ground effect across a polished hanger floor. The supporting
air cushion seemed to provide magical qualities with no tendency to flip
over at the end of flight. Solid disc Frisbees were used and it is doubtful
if the modern annular type could work on the ‘hovercraft’ principle.
K. A. Harrison, Harrogate, North Yorks
Letter: Flippin Frisbee
Could it not be that the reason why designers continue to experience
difficulties in preventing Frisbees from turning over is that their understanding
of the relevant physical phenomena is incorrect? Mace Schuurmans’s explanation
of gyroscopic motion (although it is the one given by most school textbooks)
contradicts Newton’s second law and ignores the important phenomenon of
nutation.
Fathi Tarada’s Bernoulli-law explanation for lift (although it is the
one given by most school textbooks) is well known to be fallacious. It fails,
for instance, to explain why a symmetrical wing (equal path length on upper
and lower surface) can generate lift, or how an aircraft can fly upside
down.
If the author felt that the real situation was too complex for the average
New 杏吧原创 reader to understand then it would have been better not to
write the article, than to continue to promulgate these clearly incorrect
ideas.
David J Fisher, Cardiff
Letter: Who's for unification?
We ought not to exist! If, as Harold Puthoff suggests in his article
‘Everything for nothing’ (28 July), the average energy density of the vacuum
is comparable with nuclear densities – the Universe should now be a singularity!
Whereas quantum mechanics requires a vacuum energy density – 1030 joules
per cubic metre, cosmological observations indicate a value (for the same
parameter) less than 10-10 joules per cubic metre. A discrepancy of only
40 orders of magnitude.
This is one of the deepest and most important paradoxes facing current
physics – the resolution will require a unification of quantum theory, quantity
and cosmology.
Robert Nield, Hartford, Cheshire
Letter: Who's for unification?
In his article, Harold Puthoff suggests that Boyer’s stochastic electrodynamics
(SED) approach to problems in theoretical physics may be better than that
of quantum electrodynamics (QED). Unfortunately, both approaches neglect
the critical importance of relative phase in the study of interactive oscillations.
In simple terms, radio and TV would not be possible without accurate knowledge
and control of phase relationships.
The worldwide community of quantum physicists seems not to have realised
that, if energy is quantised, then it follows that phase must be quantised
as well. Dictionaries define phase as ‘a part of the process of change’,
but say nothing of how large or how small that part may be.
Brian Clement, Crickhowell, Powys
Letter: Self-obvious
John Emsley’s article on an artificial molecule which can catalyse its
own synthesis (Science, 28 April) provokes some topical speculation. Similar
non-enzymatic auto-catalytic reactions have been shown to occur with small
biological molecules, some involving no more than four nucleotides. These
reactions have interested mainly people studying the chemical evolution
of nucleic acids, but there are possible implications for the understanding
of certain slowly progressive infectious diseases for which the causative
agents are as yet undefined.
If the component molecules of a simple autocatalytic system were available
in living tissues as part of the normal metabolic pool, the introduction
of the complete autocatalytic molecule could initiate its replication in
the tissue. The speed of reaction depends on the concentration of the complete
autocatalytic molecule and so would be expected to be very slow unless there
were micro-environments within the tissue where sequestration and local
concentration can occur. Then, a chain reaction could be set in motion and
tissue-specific damage may result.
Aggregations of a deformed version of a normal nerve-cell protein are
found in infected brain tissue in spongiform encephalopathies such as scrapie,
BSE and related human diseases. The infective agent is known to be sequestered
with this deformed protein and it has been suggested that the deformation
may in fact be caused by the binding of the genetic material of the infective
agent to the nerve-cell protein. Many of the properties of the putative
agent cannot be explained on the basis of any known group of microorganisms
or macromolecules – it is exceedingly small and does not appear to posses
any nucleic acids or proteins of its own. Could it be that the agent is
nothing more elaborate than a simple auto-catalytic molecule?
Francis Emmanuel, Marion Bain City Hospital, Edinburgh
Letter: Unclear energy
Last week’s New 杏吧原创 nicely summed up what it’s all about in the
world of nuclear energy in Britain today.
I’m alluding to the four job descriptions in the Appointments pages
(28 July). The first was headlined with the snappy eye-catcher of ‘When
did you last test a hydrogen bomb?’ and sought to recruit graduates to Aldermaston.
The next vacancy was for engineers to help the UK Atomic Energy Authority
with ‘Risk’ and reliability assessment.
The other two vacancies advertised related to what is often called the
‘backend’ of the nuclear cycle. One was for the AEA again to ‘Contribute
to the environment of tomorrow’ by working on assessing the safety of repositories
for radioactive waste.
And last but not least, the Department of Health wanted researchers
to help look for ‘causative mechanisms (not necessarily involving ionising
radiation) which might explain the documented statistical association between
the excess of leukaemia in the vicinity of Sellafield and the employment
of fathers of affected children at the plant’.
David Siddall, Cleator, Cumbria
Letter: Integrated Links
There is a point where the noise outside (inter alia Margaret Sharp
and Jacqueline Senker, Forum 28 July) overcomes forebearance and I must
complain.
The Link Biotransformations Programme did indeed get off to a good start.
Peter Baker of the Department of Trade and Industry and Maurice Lex of the
Science and Engineering Research Council saw to that when they set up the
Inter-Universities Biotransformations Centre (IUBC) in 1988. Eleven companies
and three universities are collaborating in one integrated project with
an overall budget of Pounds sterling 1.475 million over three years (expected
to rise to Pounds sterling 1.78 million within the next few weeks).
And since then, failure? Not really. The programme has now funded a
project on ‘bioactive oligosaccharides’ at Dundee (four companies supporting
a budget of Pounds sterling 800 000 over four years), and another on ‘catalytic
monoclonal antibodies’ at Sheffield (two companies supporting a budget of
Pounds sterling 440 000 over three years). A second project on catalytic
antibodies should be funded before the end of August (seven companies supporting
a budget of Pounds sterling 760 000). It is good to see Link able to fund
these two abzymes projects where other mechanisms had failed.
This group of projects, and two others, one on carbohydrate synthesis
and another on hydrolases, are expected to take the joint SERC and DTI commitment
over the Pounds sterling 2 million mark before the end of September. Clearly
the Link Biotransformations Programme will not have spent this Pounds sterling
2 million by September, but it has now fully committed the budget which
the DTI and the SERC expected it to spend in the period 1988/92.
In truth the programme is small compared with some, but it will not
escape your notice that there are still two years to run in its four-year
term for creating projects. I am now actively seeking support for projects
on biological fluorination, catalytic RNA, an interactive biotransformations
database, and a successor to the IUBC itself, to name but a few. The letters
which litter my desk are a constant reminder of what is outstanding.
I shall be disappointed not to have a number of these funded next year,
but to do so I need an increased budget. I shall not be pleased if the noise
outside causes the Link Secretariat to lose interest and turn down our request
for that extra money. Nor will the academic scientists whom I have committed
myself to support through new Link projects which are already raising the
necessary industrial interest.
Problems indeed there are. Some are endemic to the funding of science
in Britain, but patience and flexibility will remove others.
Mike Turner, Manager, Link Biotransformations Programme, University
College, London
Letter: Master gene
Two perfectly functioning X chromosomes are no longer enough, it seems,
to determine our sex. Now we all need a piece of the action on the Y chromosome,
even the majority of us who don’t have one! (Science, 21 July).
The curiously named new gene, ‘Sex-determining Region on the Y chromosome’
(SRY), only functions in less than half the population. Is there, therefore,
only one sex in the world? I always thought there were two, or have my genetics
textbooks got it wrong? Or is it that ‘sex’ means ‘male’, an elision of
words to gain some prominence for the very small and inauspicious Y chromosome?
Or is it just unfair? The first revelation of the sex chromosomes in action,
in 1905, came from the research of a woman, Nettie Stevens. Perhaps it was
a legacy of feminine modesty that led to the assignment of the letters X
and Y to the sex chromosomes, a non-contentious and equal designation, although
the X chromosome is significantly larger.
But I’m glad this gene has been located at last, despite my quibble
with the all-encompassing, erroneous nature of its name. My dear brothers
have to get some good out of such a source of sorrow to them. Their unfortunate
genetic constitution means early infant mortality and susceptibility to
so many diseases.
We can now work to limit the effects of having an SRY gene. A new feminist
project now beckons – a search to find the mechanism to switch it off, and
help our brothers to lead healthier and happier lives.
Mary Jennings, User Services Manager, Imperial Cancer Research Fund,
London
Letter: Corn and chaos
The formations of corn circles are growing in complexity each summer.
How long before we see a complete Mandelbrot set?
Martyn Hughes, Highworth, Wiltshire
Letter: Hot air
John Gribbin claimed (Talking Point, 28 July) that carbon dioxide (CO2)
emissions should be curbed prior to proof of human induced global warming.
He supported this citing the Intergovernmental Panel on Climatic Change
(IPCC) as evidence that global warming is scientifically established. However,
the published IPCC report says that air temperature has risen during the
past 30 years by ‘the same magnitude as natural climate variabilty’. Also,
‘there is no evidence that climates have become more variable over the past
few years’. It compares the historic record of air composition and temperature
with predictions of computer models of the atmosphere then argues that improved
models and data are required.
Gribbin did not mention that all attempts to find such evidence have
failed to date. All claims that global warming is occurring, may occur or
will occur are founded on predictions of highly imperfect computer models
which cannot simulate historic air temperatures. The work of Kuo, Lindberg
and Thomson (Nature, volume 343, p 709) is the only published evidence for
a relationship between atmospheric CO2 concentration and air
temperature. It confirms that average global temperature and atmospheric
CO2 are significantly correlated over the past 30 years. However,
the findings also demonstrate that changes in CO2 content lag
those in temperature by 5 months. Hence, a claim that increasing CO2
will cause global warming requires the cause to commence 5 months after
its effect has occurred. Indeed, the 5-month lag of changes in CO2
behind changes in temperature implies that increased CO2 has
negligible effect on air temperature: otherwise, any natural temperature
rise would have induced a positive feedback leading to rapid global warming
generating a climate like that of Venus.
Those who adopt scientific methods will continue to view global warming
theories with scepticism until the above, and similar, issues are addressed.
Gribbin’s attack on studies of solar activity by the George C. Marshall
Institute is typical of the journalistic behaviour used by global warming
proponents. Records of global temperature show much better correlation to
solar activity than outputs from global warming computer models. Indeed,
in 1958 Kopecky used knowledge of solar cycles to predict global temperature
for each year to 2035. His predictions have been accurate to date.
Probably the worst part of Gribbin’s article is his assertion that expensive
preventative measures should be taken prior to proof of any potential severe
risk to the global environment. Many potential risks exist or may be imagined
(modelled?). For example, a widely held scientific theory suggests that
a cometary impact destroyed the world of the dinosaurs and similar impact
would devastate our ecology. Technology exists to establish a system for
cometary detection and defence. Presumably, Gribbin wants the expense of
this. It would be cheaper than his recommendations to insure against unprecedented
global warming.
Richard Courtney, Swindon Village, Cheltenham, Gloucestershire