Letter: Cosmic coincidences
Vaughan Stone (Letters, 3 March) is right that both divine creation
(as taught in traditional religions) and pure chance (as conceived in his
letter) are equally plausible. But they are also equally speculative. The
existence of a creator deity can be neither proved nor falsified by means
of tests or observations using scientific methodology; but neither can conditions
in other universes (if any). Both contentions remain thoroughly metaphysical.
It’s vaguely puzzling that although Stone appears to have some difficulty
running with the idea of a creator god, he can manage that of an infinitely
old set of cycling alternative universes, scrolling forever through different
nuclear energy levels like some hypercosmic fruit machine, and eventually
coming up with a row of carbons! If Occam’s Razor is appropriate in the
field of metaphysics, then ‘god’ in this context would at least seem to
have the virtue of simplicity. In any case, he still doesn’t address the
question of how such a state of affairs as he outlines could have come to
exist at all . . .
What Vaughan seems to be doing here is attempting to replace theological
dogma with materialistic dogma. Personally, I feel that a cautious agnosticism
is the only sensible stance.
Trevor Danson Lancaster
Letter: Chaos rules
Chaos has become a most popular topic in venues ranging from the pages
of New 杏吧原创 to conversations at cocktail parties. If the paradigm of
chaos becomes accepted, the population ecologist may appear to be out of
business. If population trends result from purely deterministic processes
that are sensitive to starting conditions and produce chaotic dynamics,
field studies and experiments to predict population trends are doomed to
failure. Therefore, a comment on Robert May’s article (‘The chaotic rhythms
of life’, 18 November 1989) from the perspective of field population ecologists
seems appropriate.
May begins by claiming that ‘until recently most ecologists assumed
that the effects regulating density would, in the absence of other factors,
keep a population at some constant level’. For May’s ‘most ecologists’,
one should perhaps read ‘most mathematical ecologists’. The experiences
of field ecologists and mathematical ecologists are very different.
Field experience shows that it is often extremely difficult to demonstrate
density-dependent relationships. This may be due to measurement problems
or it may indicate realistic biological problems. For example, the quality
of individuals can vary with the the history of the population quite apart
from its density. Therefore, individual animals in increasing populations
can have very different relationships with their predators, parasites, food
plants and diseases at a given density than individuals from declining populations
at the same density.
For plants, relationships between density and survival can change with
moisture and nutrient content of soil, plant distribution, and competitors.
Therefore, for both plants and animals the effects of density are not
readily captured in simple mathematical expressions. Field ecologists are
not enamoured with equilibria but are impressed by variation. Chaotic behaviour
may result from some simple mathematical expressions, but these expressions
are unlikely to capture realistic population phenomena.
The following points are relevant: (1) Single, unchanging deterministic
processes do not regulate natural populations. Natality and mortality functions
continually change as the genetic and phenotypic composition of populations
shifts with environmental conditions.
(2) Describing patterns of chaotic variation does not identify underlying
mechanisms. Chaotic dynamics may arise in a variety of ways.
(3) Even if the deterministic functions commonly used by mathematical
ecologists to describe population dynamics were realistic, the parameters
necessary for chaotic dynamics are biologically unrealistic.
Nonlinear, deterministic interactions may produce fascinating and counterintuitive
patterns of change in numbers. But, while the emperor’s new clothes may
appeal to physicists, mathematicians and physiologists, perhaps field ecologists
can be excused for a less enthusiastic response.
Judith Myers, James Smith and Charles Krebs Department of Zoology University
of British Columbia
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Letter: Reactors in space
Antinuclear groups, having cut their teeth on opposing Earth-based nuclear
power, are now turning their dubious talents to opposing space-based nuclear
power (‘Protest groups move to halt space mission’, This Week, 3 March).
As in the case of conventional reactors on Earth, there are genuine good
reasons for using nuclear electricity, including economics, safety and practicality.
As the US plans the future of its space programme we realise that meeting
the need for reliable sources of electrical energy is paramount to success.
This is true whether we are establishing bases on the Moon or on Mars, conducting
explorations far from the Sun or manufacturing new semiconductor materials
or medicines in Earth-orbiting factories.
The primary factor in determining the cost of a space mission is weight.
It is a simple fact that a compact (about the size of a filing cabinet)
nuclear reactor, providing large amounts of energy, weighs much less than
a solar array that could produce the same amount of energy. This, however,
is a consideration only for near-Earth activities. For deep-space exploration,
the Sun’s energy is too diffuse even to consider using solar energy. In
deep space the solar array necessary to power a half dozen 100-watt light
bulbs would be larger than a soccer field, making the system unacceptably
heavy and awkward.
Ironically, the same issue of New 杏吧原创 carried the article ‘Space
may be ‘too dangerous’ for human beings’. This article raises the point
that heavy shielding may be needed to protect astronauts on Mars missions.
If this is the case, nuclear propulsion may be the only practical method
of transporting that much weight.
R. H. Cooper Space and Defense Technology Programs Oak Ridge National
Laboratory Tennessee, US
Letter: Beautiful chemistry
I was interested in John Nicholson’s article ‘Our brilliant careers’
(Forum, 10 March), in which he discussed his accidental route into chemistry.
I happened to read the article the day after hearing another chemist, Sir
George Porter, on Desert Island Discs.
Having just retired after 40 years as a chemist, mostly in universities,
but including a couple of years in industry, I find my experience much closer
to that of Porter than of Nicholson. Like Porter, I was fascinated by the
excitement of making crystals and colours, and bangs and ‘stinks’, and,
as a boy, I spent all my pocket money on my laboratory, which was not in
a bus in the garden as Porter’s was. Nearly all the chemists I have met
have shared this boyhood fascination with the subject.
Later, the intellectual challenge of trying to understand the double
helix, or the ceramic superconductors, or giving a judgment on ‘fusion in
a test tube’ has kept my interest alive; and the poetry is still there:
as Hinshelwood wrote, ‘To understand the secret of the rose’s fragrance
or the oak’s tenacity, that is the purpose of chemistry.’
D. W. Davies Shetland
Letter: Prawn cocktail
Your In Brief correspondent reports that the Asian prawn, Penaeus japonicus,
was caught in the wild by fishermen of the English Channel, and suggests
that it escaped from shrimp farms in Northern France (This Week, 3 February).
The same thing happened back in 1987, in the Gulf of Cadiz, where fishermen
caught the indigenous species, P kerathurus, along with ready-to-spawn P.
japonicus. In this case, it was also suggested that the animals had escaped
from shrimp farms, in the Andalusia region.
There is, however, no cause for concern: in Egypt, Turkey and southern
Spain (not yet assessed in Portugal), the two populations grow well together
without any type of apparent competition, and increasing the profits of
the traditional fishermen. In theory, these two very close species should
compete, and the Asian one, which grows faster and is more fertile, should
destroy the native one. At present, their geographical distribution is all
over the Mediterranean and Southern Atlantic coasts of Portugal and Spain.
Maria Helena Barahona-Fernandes Faculty of Science Lisbon Portugal
Letter: Nagymaros dam
Fred Pearce’s article on the controversial Danube dams in Hungary (Forum,
16 December 1989) elicited criticism from Montague Keen (Letters, 27 January)
who suggested that if Pearce had examined the dam projects with the engineers
responsible for the design and future operation of the project he might
well have found that the benefits outweighed the adverse ecological impacts.
Keen also pointed out, correctly, that a large number of scientific institutions
in Hungary had studied the impacts.
As a member of a team who did visit the sites with the Hungarian engineers,
I would like to share with your readers an additional viewpoint. In October
1988, a 10-person team from the University of Massachusetts, including biologists,
engineers, planners and an environmental lawyer, spent a week in Hungary
at the invitation of a Hungarian governmental agency. Our task was to give
advice on minimising the adverse impacts postulated from the dams. We visited
the dam sites at Dunakliti and Nagymaros and met with many engineers, academicians,
planners and biologists who had first-hand knowledge of details of the project.
Included in our team were a native Hungarian and a second Hungarian-speaking
person.
We were provided, by the government engineers, with details of the benefits
of the project, much as were summarised in Keen’s letter. We met with representatives
of the many scientific groups that had studied the impacts. We learnt of
much concern on the part of the scientists who contributed to the studies
and reviewed their recommendations. While many scientific/academic groups
had contributed there was almost no communication between them. Nor did
any one group know who the other contributors were. Participants did not
see or read what was reported by groups other than their own. Many times
we were told by scientists that the published government summaries of the
programme read as if their studies had not been done. Rarely were detailed
responses offered by the government in response to their concerns.
Our team reported to the Hungarian government that adverse impacts on
existing and potential water supplies, the quality of the Danube river water
itself, fisheries, wetlands of international importance, agriculture, rare
and endangered species and the cultural values of the Danube Bend were potentially
significant. We found that plans to mitigate these impacts were in no way
as well-developed as the engineering of the structures – which, by the way,
appeared to meet very high standards.
Mitigation proposals involving maintenance of minimum flows were generally
vague and unquantified. Water quality maintenance depended upon major expenditures
on pollution treatment facilities by Hungary and Czechoslovakia that appeared
wishful at best. No scheme had been developed to manage multiple demands
and seasonal adjustments for simultaneous allocation of water for the needs
of power generation, navigation, agriculture, fish breeding, wildlife habitat,
maintenance of municipal wells and protection of future aquifiers.
With respect to the role of the dam project in the future energy needs
of Hungary, it appears that the entire scheme was conceived and implemented
without any comprehensive energy planning process. Thus, while there is
a long-term, but apparently not near-term, need for more energy generation
capacity, one cannot say with any assurance what role the dam project would
play in a least-cost expansion strategy. It does appear that time is still
available to do a comprehensive study. Our team recommended that the Nagymaros
dam ought not to be built. We concluded that if the Dunakliti site is to
be finished much more needs to be done to assure that major adverse impacts
on health, welfare, safety and environmental functions will be avoided.
Joseph S. Larson Professor and Director The Environmental Institute
University of Massachusetts at Amherst
Letter: Pathological science
Geoff Kirby’s warning about ‘pathological science’ in amateur astronomy
(Forum, 24 February) reminded me of Richard Leakey and Roger Lewin’s warnings
about ‘pathological arts’ in archaeology. In Origins they wrote: ‘Because
theories in archaeology are often constructed from relatively litte data,
in that field the danger of over-interpretation, and therefore biased theories,
is particularly acute.’ But they continued: ‘And because of this same weakness,
truly important discoveries may be ignored.’ Perhaps there is a crumb of
comfort for amateur astronomers here.
Although Kirby ranks the Canals of Mars high in the roll of dishonour
for pathological astronomy, it is not clear to me why, just because the
Mariner spacecraft failed to detect any linear features on Mars in 1972,
it automatically follows that Percival Lowell could not have seen any in
1900, especially if, as is likely, they weren’t canals.
I for one will reserve judgment until 1992, when the Observer spacecraft
will be sent to check.
G. J. Harris Frodsham, Cheshire