I was there
I do not wish to denigrate Patrick Darling’s work in surveying Sungbo’s
Eredo鈥� the vast earthworks near Lagos
(11 September, p 38). But I must
take issue with the statement that I “did not realise its significance”.
In a paper published in 1997, Darling writes: “In 1974 I read Lloyd’s [1959]
article and resolved to study the Eredo . . .” He did not stumble across it five
years ago, as your article states.
What’s more, Darling’s recent reports substantially confirm my published
findings.
Tangled web
Matti Nummelin wrote about the problems developing countries have keeping
their virus software up-to-date because of cost
(11 September, p 56) and
proposed an open-source antivirus development programme.
Although the sentiment is great, there is one major flaw. Antivirus software
source cannot be open-source, because the virus writers would then have access
to the same source to develop viruses that were immune to it. The people who
write viruses are resourceful enough as it is, without any organisation giving
them such an opportunity to get ahead!
Letter
Virus authors have not been heard in the debate. Everyone seems to assume
that we are electronic-age vandals, equivalent to arsonists, trying to see how
much we can destroy for our own thrills. The truth is that most virus writers
are not the people who spread viruses.
Virus authors are proud of their creations, and will distribute them to other
virus authors for appraisal, bragging and help鈥攂ut this does not
constitute spreading. Spreading is the malicious sending of a virus, worm or
Trojan horse. Authors send viruses to antivirus companies’ researchers for the
benefit of the public. Some are encouraging people new to the scene to release
their viruses in a special forum as source code for appraisal, rather than
spreading them. The aim is to reduce the number of viruses getting into the wild
by showing newcomers that recognition be earned in better ways than getting your
virus reported in the wild.
The antivirus industry, meanwhile, tells people that their software can
detect 100 per cent of all known and unknown viruses. They do use what are
called heuristics to detect anything “virus-like”鈥攂ut if they haven’t seen
it, how do they know what it is? A whole group of authors out there are writing
viruses specifically to embarrass the people who perpetuate these half-truths:
they are egged on by the arrogance of the claims.
My own virus collection is now destroyed and my virus code (never spread or
distributed by the way) is destroyed. I don’t feel I am in the wrong for having
coded viruses. I welcome discussion of these matters.
Junk joules
Robert Matthews mentions Roger Penrose’s mad-scientist proposal to extract
clean energy from an “off-the-shelf” black hole by throwing a skipful of junk at
it in the right way
(28 August, p 24).
The hole would eat up the junk and hurl
the empty skip back out again with more energy than it had before.
Unfortunately, the closest such hole is likely to be too far away to be
useful.
However, gravitational energy can be similarly extracted from the Earth
itself. Junk from a near-Earth-orbit asteroid (or the Moon) could be made to
fall towards the “edge” of the Earth’s atmosphere. Controlled horizontal
collisions with orbiting impact-powered generators could convert part of its
kinetic energy first into electricity and then into microwave beams (or
very-high-velocity junk) directed towards energy collectors on Earth and to our
asteroid (or the Moon) for launching additional junk and repeating the
cycle.
Bubbles
Why do Brits have the strange notion that bubbles go on cleaning our dishes
after we have placed them on the drainer? Why, otherwise, do most people in
Britain not rinse their dishes?
Washing-up liquids contain oestrogen mimics which may cause cancers and have
been shown to bring about feminisation in alligators. People will say that we
have been doing it for years and hey鈥攚e’re all fine, what’s wrong with it?
But why are we the only country that does it?
Viruses at war
When it comes to the proposals for controlling drug-producing plants such as
cannabis with a herbicidal fungus, it is depressing to see New 杏吧原创
tamely joining so many others in issuing warnings of doom and gloom
(11 September, p 3).
As someone who used to teach plant pathology, I have two comments. Firstly, a
very patchy and incomplete kill of the target plant is likely. Whether foliar
pathogens infect leaves depends on the temperature and moisture at the leaf
surface. Even if the leaves do become infected, the epidemic will peter out if
conditions are not right for rapid secondary spread. We know this because nature
practises this kind of warfare on a large scale in many tropical countries.
Secondly, Fusarium oxysporum is not a foliar pathogen. It infects
plants via the roots. It has to establish itself in the soil before it can do
any damage, and has to compete against a veritable jungle of resident
microorganisms to do so.
The argument you deploy, that such methods could inspire terrorists to
produce biological weapons that destroy normal crops, would bring to a halt all
research on the development of weed-control fungi. This would be a pity because
such agents should have the advantage over chemical alternatives.
Information info
In his feature on whether life is inevitable
(18 September, p 27), Paul
Davies says “throwing energy willy-nilly at amino acids will not create delicate
chain molecules . . . in the same way that putting dynamite under a pile of
bricks won’t make a house”. Although a colourful analogy, this is
incomplete.
If bricks assembled in small groups tended to attach themselves to other
bricks, if you weren’t particularly concerned about what sort of house you made,
if you had a low-level continuous earthquake going on beneath sufficiently large
numbers of piles of bricks and if you didn’t have a deadline to meet, then
dynamite just might do the trick.
Try to visualise it; it’s very entertaining. Perhaps we can construct a
Molecular Dynamics model of the whole thing and air it on MTV.
Letter
“An apparently random sequence such as 110101001010010111… cannot be
condensed into a simple set of instructions, so it has a high information
content,” Paul Davies writes. However, this notion of “information content”
leads to paradoxes.
Suppose a random number generator program produced 100 and 1000 random
numbers. The second sequence of numbers seems to have an information content ten
times higher than the first, because its description would be ten times longer.
In fact they are both generated by the same simple set of instructions, so have
exactly the same “information content”.
One needs to know the meaning of a sequence to capture its true information
content.
Wet blanket
Shigenori Maruyama and his colleagues calculate that the oceans are losing
water to the Earth’s mantle
(11 September, p 4). However, they seem to have
assumed that the total amount of water on Earth has remained constant.
In fact, some estimates of the quantity of water arriving in small and large
asteroid collisions suggest that the entire planet should be covered by water.
The net absorption of water into the mantle might explain why there is still
some dry land.
Indeed, our existence may depend on a knife-edge balance between new water
arriving in asteroids of all sizes and the net absorption of water by the
mantle.
However, this suggests that the mantle began soaking up water early in the
Earth’s 4-billion-year history, rather than the process beginning 750 million
years ago, as Maruyama thinks.
You are an alien . . .
We wonder whether the radio message that Charles Seife describes
(18 September, p 36)
could be understood only by aliens who are implausibly similar
to ourselves. To develop our understanding of what is involved in communicating
with aliens, and how to construct such messages, we propose the following game
involving two teams Home and Away:
Imagine some distant aliens who suspect the presence of life on Earth. They
do not share all our presuppositions but wish to communicate. The Away team, the
aliens, have to construct the kind of message they might send, building upon
their imagined way of thinking. Can the Home team, those who think that we know
what is required to communicate with aliens, decipher this test message? If
early efforts were indeed deciphered, the same exercise could be repeated,
systematically imagining aliens who are progressively more different from us.
Letter
I tracked down Yvan Dutil through a Web search, and he kindly provided an
address for the full message to aliens:
www.contrib.andrew.cmu.edu/~mm4b/inter-comm.html
Best bang so far
Reader Stephen Parish makes the valid point that we cannot be certain that
the red shifts of galaxies are caused by them moving away from us
(18 September, p 58).
It’s simply our best guess at what is happening based on known physics.
However, he also suggests that red shifts may be caused by the photons losing
energy as they travel.
Such “tired light” models have been around for a long while, and they have a
number of well-known problems, the most serious of which is an inability to
reproduce the black-body nature of the cosmic microwave background radiation.
Cosmologists do not embrace the big bang model because it reassures them to
think there might have been a beginning, but because it’s the model that best
explains the observations.
All reputable scientists would acknowledge that, in spite of this, it might
be wrong. And to remove it from its place as the standard picture, it’s
necessary only to find a model that does a better job!