Letters: Obvious neutrinos
It is a pity that Steve Currie (Letters, 29 August) chose the neutrino
as an example of something for which there is no direct evidence. One can
quibble about what is direct and what is indirect, but the neutrino can
do just about anything the photon can except be detected by the human eye.
It carries away large amounts of energy from nuclear reactions in an
obvious and readily detectable way (especialy from beta decay). It can
impart kinetic energy to electrons with which it collides, and their direction
of recoil indicates the direction and probable source of the impinging neutrinos.
The neutrino can also bring about much the same nuclear transformations
that the photon and other energetic fundamental particles can, but because
it interacts via the weak force rather than the strong or electromagnetic
the reactions are very much rarer.
There are many other particles for which the evidence is far scarcer
and more indirect, if indeed there is evidence for them at all. How about
the Higgs boson, the gravitano, the photino, the gluon, the glueball, the
axion, the top quark (or for that matter, any sort of quark) and the magnetic
monopole, to mention but a few? If there were half as much evidence for
God as there is for the neutrino, I for one would be converted.
Michael Walsby Hereford
Letters: Lightning calculation
When I was a child, it was common knowledge that you could calculate
the distance of thunder and lightning based on the time between the two
measured in seconds: for example, ‘Flash – one thousand and one, one thousand
and two . . . one thousand and seven – Bang!’ That was seven miles away.
Recently I experienced a thunderstorm in the presence of my brother-in-law
(who is French) and he used exactly the same calculation, but his answer
was in kilometres! This seemed both to confirm the widespread use of the
method and to imply this is due to its simplicity rather than its validity.
As I see it, the calculation is still extremely simple, since the light
is seen virtually instantaneously while the thunder travels at the speed
of sound, approximately 760 miles per hour, and thus 0.211 miles per second.
Therefore the time lag in seconds should be divided by five (4.7 if you’re
using a stopwatch) to get the distance in miles, or divided by three (2.9)
for a distance in kilometres.
John Williams St Galmier, France
Letters: Reincarnation
I am compiling a book of previously unpublished accounts of reincarnation
and near-death experiences.
If any of your readers believe they have lived previous lives, or have
reached the brink of death before being resuscitated, I would be delighted
to hear from them.
Vivienne Rae-Ellis PO Box 5159, Bath, Avon
Letters: Mail made easy
Re Colin Singleton’s letter ‘Character count’ (15 August). On 18 August
I sent a letter air-mail to a friend in Worthing, from here, using only
the house number and postal code, total 9 characters plus UK. The letter
was delivered on 25 August, in seven days, about the same as with a conventional
address. Surely we are on to something. Thank you Colin Singleton.
Eric Smith Antigua, West Indies
Letters: Easy life
In reference to Comment (29 August), we would like to give the point
of view of two second-year physics undergraduates. To quote a recent Radio
4 economics programme, just after the release of the A-level results:
‘Most students go to university, not for a challenge, but for something
easy to do for three years. This is why places on politics, English and
philosophy courses will always be in greater demand than those in science
and engineering that are actually essential to the country’s economic growth
and wellbeing.’
When visiting our BA friends at this and other universities, it is disheartening
to discover that they are obtaining firsts and upper seconds after doing
the same amount of work (and attending only two-thirds the lectures) we
would have to do to obtain a low third. It is ironic that they will on
average out-earn science and engineering graduates on a ratio of two to
one.
Our childhood passion for the physical sciences will remain with us.
However, practicality has to overtake idealism.
We could leave after obtaining our degrees and become, for example,
House of Commons researchers on 拢14 000; do a two-year law conversion
and look at a starting salary of around Pounds sterling 20 000, or we
could stay with the subject, spend three years on a PhD and then go to a
postdoctoral salary of 拢12 000.
This letter was borne of conversation between more than a dozen undergraduates
in a physics common room. The general consensus was that almost anything
was better than the last option.
The manufacturing base of this country undoubtedly won’t notice the
loss of a couple of physicists – it probably wouldn’t miss the dozen of
us – but if this conversation is repeated in the universities, colleges
and polytechnics throughout the Britain, then we fear for the economic wellbeing
of this nation.
Neil Walker and Richard Jordan University of Leeds
Letters: Opportunity lost
Andy Coghlan’s otherwise excellent comments on my lecture at the BA
Science Festival (This Week, 29 August) imply that I blame technology for
the tragedy that worldwide there are now more people than ever before suffering
from acute hunger and abject poverty.
In my lecture I pointed out that advances in technology had, since 1950,
resulted in dramatic increases in production of food (x 3.3), manufactured
goods (x 6) and energy (x 5). This was ‘a triumph of technology which
offered mankind an unprecedented and probably unrepeatable opportunity to
lift the spectre of hunger from the peoples of the earth, and to free hundreds
of millions of human beings from a life of grinding poverty and unremitting
toil’.
Tragically that opportunity was lost because medical technology was
used with commendable success to reduce the death rate (especially in the
Third World) but there was a failure to use it to bring about a corresponding
reduction in the birth rate. Consequently, Third World population exploded
during the 40-year period from 1.8 billion to 4.3 billion.
That increase has caused untold human suffering and environmental damage,
with the prospect of much worse to come as Third World population continues
to increase at the rate of about 90 million per year, or 1 billion in 11
years.
Technology is neutral. Results depend upon the way it is used – or in
this case the way it is not used.
Robin Cole Winchester
Letters: Worth listening
Sam Freeth’s article on Lake Nyos (‘The deadly cloud hanging over Cameroon’,
15 August) provided some interesting new material on the events after the
1986 Lake Nyos explosion, but sadly posed yet more questions. The phenomenon
of inverted thermal stratification proposed by Freeth would appear to be
rather surprising to most limnologists, who have managed quite well for
many years with the more conventional phenomenon recorded in almost all
deep tropical lakes. Stratification increases, not decays as he proposes,
as the surface water of freshwater lakes warms up. My suggestion that a
seiche produced by a strong wind across the lake when it was fully saturated
could have triggered the event (Letters, New 杏吧原创, 29 September 1988),
which now appears to have been adopted by the experts, assumed rather more
conventional lake physics, with which few limnologists would disagree.
Of rather more concern, however, is the assumption that because scientists
cannot fit the reports of people who actually experienced the event into
their theoretical model, those people must therefore be wrong, or even suffering
from ‘olfactory hallucination’. Such intellectual arrogance is the bane
of field science, as Sir Arthur Conan Doyle well appreciated almost a century
ago when he wrote, in the words of his famous scientific detective Sherlock
Holmes, ‘When you have eliminated everything which is possible then whatever
remains, however improbable, is the truth.’
Interpreting uneducated people’s conceptual frameworks often presents
formidable intellectual challenges, but in my experience that effort is
always worthwhile. If the people say that the smell and noise were simultaneous,
then it is worth taking this as the basis for a new hypothesis. For example,
some snow avalanches act as if they are aerosols travelling in low temperature
air currents, and can travel down even slight slopes at extraordinary speeds,
generating a terrifying noise as they pass. It may be that the Nyos carbon
dioxide aerosol resembled such an avalanche in the valleys below the lake.
Nor are the medical symptoms – especially of skin blistering – consistent
with partial suffocation. If the local people reported specific smells (or
tastes?) then it is worth taking a little more trouble in trying to develop
a new hypothesis about the associated chemistry, rather than simply dismissing
these reports as lacking in objectivity.
Douglas Cross Honiton, Devon
Letters: Heading our way
There has been much discussion recently of possible cosmological causes
of global catastrophe over the Earth’s recent history. Random comets from
the imaginary Oort cloud and rogue asteroids are popular enemies.
The recent precise measurements of the velocity of the star Lalande
21185 (New 杏吧原创, Science, 1 August) suggest that a complete star system
may arrive in our midst in under 30 000 years. Now that should produce
some interesting effects.
J. Whitman Barnham, West Sussex
Letters: Video visibility
I leap to the defence of the Beach Boys whose latest environmental venture
(so Feedback, 15 August, tells us disparagingly) is to provide video cameras
to environmental groups so that they can film their local environmental
problems and solutions.
There is considerable evidence to suggest that video is a powerful medium
both for propaganda purposes and for bolstering self-esteem. It is particularly
useful for groups who are illiterate or who speak a minority language. It
can also be used by those who have little financial and political power.
The visibility of what are considered to be environmental problems
is usually decided by those in power; so too are the solutions. I commend
the Beach Boys for having the humility or the percipience to understand
that ordinary people all over the world, with few resources and no publicity,
meet and tackle environmental problems all the time. It is from these examples
that other ordinary people can learn best how to deal with the pollution
(or whatever) in their own back yard.
The sort of films that the Beach Boys are backing do several admirable
things: they provide a visual record of the project for the local environmental
group so that the next venture is easier to plan; they provide graphic ammunition
for a local lobby to combat opposition; they provide examples and propaganda
for others so that local initiatives are encouraged.
I think that it is Feedback that has missed the point.
Sarah Murray Bradley London
Letters: Hole counts
After reading John Gribbin’s letter (15 August), I felt quite embarrassed
that I would have overlooked a paper by Roger Blandford. I therefore asked
Blandford whether he could give me the reference of his estimate of the
number of stellar-mass black holes in the galaxy, of about five years ago,
as no such estimate is given in the published conference proceedings to
which Gribbin referred. I here quote from Blandford’s answer: ‘I think
I quoted a rough estimate which was so uncertain that I did not include
it in the written version. We know more about compact object demography
and so anything said then is pretty irrelevant’.
It is apparently this unpublished rough estimate, which Gribbin may
have remembered from Blandford’s talk.
The difference with the approach in my paper is that, in addition to
(necessarily uncertain) theoretical estimates, I was able to use the new
observed fact that there are now three black hole binaries with low-mass
companions known in our neighbourhood in the Galaxy (two of these were discovered
only this year).
This fact provides for the first time a good basis on which to make
a quite firm estimate of the number of stellar black holes in the Galaxy,
which was not possible five years ago.
E. P. J. van den Heuvel University of Amsterdam The Netherlands
Letters: Mea culpa
Take care! One at least of your readers is a Latin scholar. ‘Raptor’
is derived from the verb ‘rapere’, not ‘raptere’ (‘Birds of prey fly again’,
22 August).
Dorothy Forrester Edinburgh
Letters: Boozy bees
Your Science section is full of surprising facts on recent research
results. Here you got the story of the bees that get drunk on fermented
nectar (8 August). Now, in human society it is a fact that males have a
much boozier life than females (at least on average). Not so with honeybees.
The drone (male bee) that you chose to show in the picture that goes with
the article will certainly not drink fermented nectar from flowers, as it
doesn’t drink nectar from flowers at all but gets fed by busy workers (female
bees) in the hive.
Honeybee society and human society have much in common, but here they
are different.
Dorothea Bruckner University Bremen Germany