Letters: Laughing gas
Tom Nash (Letters, 14 December) makes some incorrect assertions about
nitrous oxide (N20). He is right in saying that it is not produced
(at least significant amounts) by automobile engines: these are a source
of nitric oxide (NO), which makes an important contribution to pollution
of the lower atmosphere, and to acid rain.
Nitrous oxide comes mostly from biological sources, but not ones designed
to produce carbon dioxide (although the electronic structures of these two
molecules are indeed very similar). Rather it is a by-product of the reactions
involved in the global cycling of nitrogen in the environment.
Nitrous oxide is chemically inert in the lower atmosphere, although
it absorbs infrared radiation and so is a ‘greenhouse’ gas like carbon dioxide.
In the stratosphere it reacts with oxygen atoms and ultraviolet radiation
to give nitric oxide, which does have an important effect on the ozone layer.
For both these reasons the presence of nitrous oxide in the atmosphere is
significant, even at the low concentration of 300 parts per billion.
Although it appears to be of ‘natural’ origin, its concentration has
increased appreciably over recent decades. The reasons do not seem to be
understood, but one cause could be changes in agricultural practice, especially
the increased use of fertilisers.
Tony Cox Inorganic Chemistry Laboratory University of Oxford
Letters: 'Ere we go . . .
Hey, referee! William Bown’s analogy between football and the brain
drain was indeed apposite (Forum, 30 November 1991).
I was over the moon when New 杏吧原创 published my attempt to set the
record books straight about government distortion of brain-drain statistics
(Talking Point, 29 September 1990). But now I’m as sick as a parrot about
your own-goal of an article which trots out the same old myths put about
by those ministerial hooligans: ‘British science is healthy . . . because
it attracts more scientists from abroad than it loses’ and ‘the total gain
. . . shows an encouraging trend’.
So, with an E-I-Addio, here is my action replay.
For example, figures put out by the Department of Education and Science
claim that only 160 academics in all subjects left Britain in 1988, and
that this was fewer than those who came in. However, these figures deliberately
exclude postdocs and graduate students who, as most working scientists know,
constitute the bulk of the brain drain – primarily because they were unable
to obtain permanent positions in Britain.
They also refer only to those who are known by the universities to have
definitely left Britain and, again, deliberately exclude the 577 others
(those who are known to have left for reasons other than retirement or because
they have taken non-university jobs in Britain).
Even with just six months of its rather haphazard chain-letter inquiry,
British 杏吧原创s Abroad collected 10 times as many signatures in science
alone as the purported 160.
The US National Science Foundation also records that about 1000 scientists
and engineers are granted permanent residency in the US every year.
Moreover, none of these statistics takes account of the quality of those
who are leaving Britain and those who come to take their place. For example,
the cream of Soviet physics and mathematics researchers is currently abandoning
the former USSR, mainly for the US; very few of them have come to Britain.
Before the final whistle, let me point out a hat trick of other defensive
blunders in your article. (1) The British 杏吧原创s Abroad petition from
1600 expatriate scientists was presented to the Prime Minster in 1990, not
1991; (2) It was to Margaret Thatcher not John Major; (3) It did not say
what you said it did; that quote was from a letter by 72 expatriate Fellows
of the Royal Society and Fellowship of Engineering.
As they used to sing on the terraces: ‘Whatta loada rubbish!’
Michael Duff Texas A&M University College Station, Texas
Letters: Eat your greens
Richard Ladle’s article on the health consequences of cannibalism (Science,
7 December) referred to the relationship between cannibalism and Kuru in
the highlands of Papua New Guinea. While it is true that a handful of people
continue to fall victim to the disease, no one born after 1959 has ever
been infected – for that was the year cannibalism ceased in the Kuru region.
In less isolated areas of the country, it ceased many years earlier
or had never been the local custom.
In fairness to the people of the Kuru region, and to Papua New Guineans
in general, may I suggest the use of the past tense when writing about cannibalism
in future.
Andrew Collins University of New South Wales Sydney Australia
Letters: Zero point
Several of your recent reports have indicated that the hypothesised
‘zero-point’ energy of electromagnetic field fluctuations is nowadays being
taken seriously by physicists.
Harold Puthoff explained in his article ‘Everything for nothing’ (28
July 1990) how zero-point fluctuations correspond to the ‘uncertainty’ of
quantum mechanics, and lead to an understanding of quantum phenomena such
as photo-electron emission, the Casimir effect and the black-body radiation
curve. The alternative approach is coming to be known as ‘stochastic electrodynamics’.
On this approach, stochasticity is no mystery, but intrinsic to both the
quantum and macroscopic universes.
In their article ‘What is light?’ (2 November), Dipankar Home and John
Gribbin describe new beam-splitter experiments that are supposed to settle
the famous old conflict between photon and wave-packet descriptions of light.
But as they mention, Trevor Marshall and Emilio Santos have shown that zero-point
fluctuations would frustrate a definitive result.
If Puthoff is proved right in postulating that gravity can also be explained,
via zero-point energy fluctuations, as a long-range Casimir effect (Science,
31 August) then stochastic electrodynamics would offer a great advance over
the set of formal rules constituting quantum mechanics.
Max Wallis School of Mathematics University of Wales Cardiff Trevor
Marshall Department of Mathematics University of Manchester
Letters: No reward
Recently I discovered among my mother’s books an 18th-century handwritten
volume of observations and reflections about the behaviour of the English
ant.
Out of curiosity, I took it to the Natural History Museum, to try and
learn about it. They were unable to help me, but were sufficiently interested
in it and its contents to persuade me to donate it to the library. It would
seem to be a unique document of scientific and historical interest.
We would like to discover more about it, and it is possible that some
New 杏吧原创 readers may be able to help. The only definite information
available is that it was written by one Isaac Padman in 1796 – a person
who is otherwise totally unknown.
The text itself suggests that he was well educated and wealthy. The
most likely thing is that he was a clergyman, or course, but church records
are unable to either confirm or deny this. It is fairly probable (though
not certain) that he lived in the Home Counties.
If anyone can help in this quest to trace Isaac Padman, we would be
grateful if they could write either to me or to the Natural History Museum.
There is, I regret to say, no reward on offer – except the satisfaction
of helping to solve an enigma.
David Strank 76 Main Street Stapenhill Burton on Trent Staffordshire
Letters: Computing support
Ian Lloyd’s plea for more computer power for Britain’s researchers as
reported in ‘Feed a pensioner, starve a supercomputer’ (This Week, 14 December)
is timely, and must surely be of critical importance for British industry.
But in weighing it in the balance against a humanitarian need – an old
person’s to keep warm and be properly fed in the winter – he has scored
something of an own goal. It’s such a glaringly obvious error that it smacks
of ideology or desperation, or both.
He is right in saying that we must be prepared to face difficult decisions
– too true. But instead of robbing the most vulnerable members of our society,
what about a bit of belt tightening amongst the wealthy and privileged?
The executive company car would be on my hit list, and if industry insists
on rewarding itself excessively then the state should claw some of that
back in higher taxes.
Yet it is not this that is really the issue, but the inability of successive
governments to get their priorities right. If there’s a will, the money
would be there.
Terry Miller Waddington Lincoln
Letters: Believe it or not
In ‘A new age dawns for science’ (Forum, 14 December) Robin Allen refers
to a result frequently cited in the parapsychological literature, that ‘sceptics
rarely obtain positive results in psi experiments . . . because their scepticism
inhibits the production of psychic phenomena’.
I’m sure that most readers will have realised that this too is a parapsychological
phenomenon, of a sort. However, (and this is the important point) I don’t
believe it!
My disbelief in this effect is in fact so total that I am prepared to
guarantee it never occurs in my presence and, for a modest fee, I am happy
to offer my services to any of the existing investigators of parapsychology.
No longer need sceptics worry that their beliefs will prevent their
results getting a fair hearing, for my ‘meta-sceptism’ will prevent their
doubts from influencing the outcomes of their experiments.
I anticipate great advances in New Age science, as well as in my personal
income – unless the whole enterprise is spoiled by some doubting Thomas
who refuses to take me seriously . . .
Mark Bassett New Malden Surrey
Letters: Morning mists
Perhaps Anthony Edwards should have waited a little longer for the morning
mists to clear from around his bathtub (Forum, 7 December), for he has erred
by a factor of 1000 on two occasions in his opening paragraph. Four hundred
megalitres of shampoo would be 88 million gallons, rather than ‘nearly 100
000′, and the conversion factor relating M and m is a billion (109) not
a million. I feel that Edwards is perhaps confusing his M’s with his K’s
– those morning mists again, maybe.
Michael Wells Currie Midlothian
Letters: Cement coating
In Leigh Dayton’s article about our new cement surface coating (Technology,
30 November) it was incorrectly stated that 98 per cent of incoming solar
radiation would be converted by such a surface.
Actually these new surfaces initially absorb about 92 per cent of incident
radiation and radiate only 2 per cent of that of a black body at room temperature,
rising to 5 per cent at 400 掳C. The photothermal conversion efficiency
at 400 掳C is currently about 80 to 85 per cent with conventional steam
turbines and a peak conversion efficiency to electricity of 27 per cent
is suggested using low-cost collector technology.
David Mills Department of Applied Physics University of Sydney Australia
Letters: Behind BT's horns
I was interested to see that like me, Ariadne (14 December) has been
observing the new BT logo, but as a student of musical instruments the first
thing I noticed was that the instrument being played is not a trumpet, but
an aulos.
This is an unusual thing to see advertising a modern, high-tech organisation,
as it is of early Greek origin.
The aulos was a woodwind instrument. It probably had a double reed (like
the oboe), and was often depicted, like the BT one, as having two pipes,
one played with each hand.
According to the Greek writer Theophrastus (circa 372-287 BC) the aulos
was composed of three parts: the mouthpiece, the middle joint and the foot
joint. The first and third parts were made of reed, and the middle joint
of bone or ivory.
I should love to know the reasoning behind BT’s choice of this obscure
but fascinating instrument. To me at least, far from inspiring thoughts
of late 20th-century technology, the aulos conveys a spirit of tranquil
antiquity when the need for superfast communications was the furthest thing
from people’s minds.
Allison Scott Edinburgh
Letters: Winter wonderland
Reading the letter from Anita Langham (14 December) entitled Window
Wonder I found memories flooding back of a similar occurrence I observed
on a number of occasions at the home of my parents.
Standing on the window ledge in their front room is an old copper kettle
approximately four inches from the glass. As usual, during cooking or the
drying of washing on radiators the window would steam up. Once the cause
of the increased humidity was removed the window would begin to clear.
On a number of occasions when the gas fire in the room was in use almost
all of the window would clear leaving the clearly defined image of the kettle
on the window in the form of condensation.
For some time the cause of this image was a mystery until it was noticed
that the image on the window, the kettle and the gas fire were in perfect
alignment. This led me to assume that the effect was caused by the radiant
heat from the gas fire heating the window slightly and removing the condensation,
while the kettle cast a shadow which kept that portion of the window cool
enough to sustain the condensate.
Perhaps a similar heat source or shadow may account for the patterns
observed by Langham.
Jonathan Dabbs Rotherham Yorkshire
Letters: Over the rainbow
J. C. A. Craik described a remarkable pair of intersecting rainbows
(Letters, 7 and 21 December), a normal rainbow (bow 1) and a fainter, elevated
copy (bow 3), together with the usual secondary rainbow (bow 2) associated
with bow 1.
Perhaps bow 3 arises from a reflection of the Sun off calm water out
to sea to the west of his position. The centre of bow 1 will lie, as usual,
on a line from the Sun to the observer. Similarly, that of bow 3 should
be in line with the observer and the mirror image of the Sun reflected in
the western sea.
On account of the reflection, bows 1 and 3 should be equally depressed
beneath, and elevated above, respectively, the eastern horizon of the flat
plane on which he was standing. The bows should, therefore, intersect at
this horizon, as observed.
But could the sea ever be calm enough on a rainy day off the west of
Scotland?
Gordon Kirby Chemistry Department University of Glasgow
* * *
With reference to J. C. A. Craik’s third rainbow I have been intrigued
by a related phenomenon – that of seeing a rainbow apparently reflected
in a water surface. Because a rainbow is a virtual phenomenon the apparent
reflection is not a reflection at all but is an entirely new bow seen from
a remote vantage point on the surface of the water.
It is possible to have a set of circumstances where there appears to
be a bow reflected in the water without there being a bow visible in the
sky.
David Shrewsbury Tighnabruaich Argyll
Letters: Through a glass
After a particularly enjoyable staff Christmas party, I chanced to flick
through my 23 November copy of New 杏吧原创. I then noticed that, in the
article ‘Meet the molecular superstars’, the first colour graphic became
visibly three-dimensional.
Similar effects were noted with other graphics in the article.
After further research with colleagues on this phenomenon, I have discovered
that it only takes (relatively) small amounts of alcohol to produce the
effect.
Does this make holograms obsolete? I would be intrigued to hear others’
views.
James Neal University of Newcastle