For the record
鈥� In our article on recycling old ammunition (30 August, p 13) we listed the constituents of gunpowder as the classic mixture of potassium nitrate, charcoal and sulphur. But as several readers have pointed out, modern firearms cartridges do not use that age-old recipe. Instead, they are based on nitrocellulose or nitroglycerine mixtures. It is the limited shelf lives of these compounds that necessitates their disposal.
Reduce demand
The pro-nuclear letter-writers of your 30 August issue refer to the “40 per cent increase in electricity demand predicted by 2020” (p 22). But that is where a big part of the problem lies 鈥� we want to continue using ever more energy, even though we don’t have good ways to do so. Does the “pursuit of happiness” necessitate an ever-increasing use of the world’s resources?
As to the statement that it is hard to see how renewables can substantially replace fossil fuels in the long term, it is only renewables and fusion that can provide a truly long-term solution, theoretically millions of years. Uranium, and thorium for that matter, are limited resources. Even fusion presently requires the rare element lithium.
Dishonest whalers
Your recent statement that Iceland’s stance on its “scientific whaling” programme is no more dishonest than that of the opponents of industrial whaling, such as the UK and US, demonstrated a woeful lack of understanding (23 August, p 3).
Contrary to the myth that is peddled by whaling countries, whale populations are not exploding around the world. With a few notable exceptions, most populations of large whales remain at less than 20 per cent of their initial abundance, particularly in the southern hemisphere.
Whaling nations are prone to using selective extracts from the IWC Scientific Committee reports to bolster their case. In fact, there is far more doubt about the populations of minke whales in both northern and southern hemispheres than your article suggests.
For example, over 20 years’ worth of data has been collected during minke whale-sighting cruises in the Southern Ocean, at a cost in excess of $60 million, and yet there is still no agreed population estimate. Those countries that argue a case for sustainable hunting and killing of whales are surely obliged to first demonstrate a reliable and repeatable method to estimate abundance.
The arguments against killing whales are scientific, moral and ethical. Even if whale populations were ever to recover to their previous abundance, New Zealand would still be opposed to commercial hunting, which is an activity whose time is now past.
None of the established whaling countries need whale meat as a source of food, and the economic benefits of whale watching far outweigh those of whaling, which has been heavily subsidised for years.
Earthrise
Greg Klerkx suggests: “Picture yourself on the moon, watching Earthrise over an eerie landscape of lunar craters and peaks. It’s just a fantasy, surely?” (30 August, p 25).
Surely. The Earth doesn’t rise there, as the moon’s rotation is orbitally locked.
Letter
I hope Klerkx warns his clients for moon travel that to watch Earthrise they will be confined to a fairly small strip of the surface, where the Earth rises and sets thanks to the slight monthly wobble in the moon’s orientation. You can see just how small at
The editor writes:
鈥� Even though Greg Kavalec is right that the moon always presents the same face towards Earth, its wobble lets us see 59 per cent of its surface, as can be seen on the NASA website that Richard Hilken mentions. Lunar hoteliers who want to give their guests a room with a view of the Earth rising should build at the poles or at the edge of the area facing the Earth.
Blinkered defence
Philip Cohen’s report of how some experts have reacted to suggestions that the theory of universality of the genetic code might be flawed provides yet another example of scientists defending a favourite theory with all the blinkered dedication of a lioness defending her cubs (30 August, p 35).
The pervasiveness of this attitude in disciplines as diverse as biology and astronomy, and the frequency with which it appears, should be a constant reminder to us all that the world’s greatest scientific minds once knew beyond doubt that the universe rested on the back of a giant turtle.
No chalk on Mars
You report that the absence of significant carbonate deposits in basins and gullies on Mars suggests that there were no large pools of water on the planet in the past (30 August, p 12).
Although it is possible for carbonate rocks to form through inorganic reactions, the vast majority of the carbonate rocks on Earth have been formed through biological activity.
For example, the chalk of the White Cliffs of Dover consists almost entirely of the fossilised shell cases of coccolithophores, minute sea-living organisms variously regarded as algae or protozoa, now most commonly classified as protists. Similar organisms such as radiolarians and foraminiferans are also involved in chalk (and limestone) formation.
The absence of these massive deposits on Mars is therefore evidence of a much more restricted kind for the absence of a certain type of life, rather than for the much more general inference that there have never been large pools of water on the planet.
Lengthy transmutation
Laser transmutation certainly has a long way to go (23 August, p 10). It was noted that the 1017 pulses needed to transmute the small sample of iodine-129 into iodine-128 would need the energy of a dedicated power station.
More problematic, however, is the pulse rate of one per hour. Transmutation thus requires over 1013 (10 trillion) years. With a half-life of a mere 16 million years, the iodine-129 would decay completely over a fraction of this time.
Fly on the wall
Unfortunately Mark Robinson’s patent application for his technique of killing flies must fail, as I claim prior art (Feedback, 30 August). I have used this technique for decades, having learned it, I think, from my late father.
There is also another technique that he taught me: clap your hands just above the fly. On seeing the rapid approach of the two objects (your hands), the fly immediately flees, but straight into the trap.
Uniformly vulnerable
In your article on computer antivirus strategies, you describe the results from Hewlett-Packard researcher Matthew Williamson’s computer model that mimics the way in which viruses spread, based on a model that tracks the spread of biological viruses (6 September, p 6).
Any analysis of biological systems will highlight the risk caused by genetic uniformity. This has been the downside of factory farming with monocultures of highly uniform varieties. In the computer world it is the lack of variation in operating systems that creates vulnerability and facilitates the spread of viruses. Pick a computer at random, as a virus does, and it will almost certainly be running a Microsoft operating system with common applications.
The easiest way for a business to reduce the threat from viruses is to choose a little-used operating system and applications.
Letter
If you take two rolled up newspapers and bring both slowly into swotting position simultaneously, the fly sits quietly as its response system is stuck between the two incoming threats. Many dead flies have proved the practice.
Letter
Robinson has overcomplicated fly swatting with his slow approach and flick method. If he simply remembers that flies take off backwards and aims his rolled-up newspaper a couple of inches behind the fly, he will get a 100 per cent kill rate.
Photography is art
Tony Straka cites the case of Bridgeman vs Corel to argue that photographs of paintings in the public domain cannot be protected by copyright (6 September, p 24).
He should be aware that the decision is widely considered to be of doubtful authority. Aside from being binding only in New York state, the case was flawed because crucial evidence was never presented to the judge. It would be news to art photographers (and scanning technicians for that matter) that their work merely consists of “slavish” copying of the paintings they photograph or scan.
Taking a picture of a painting is far more than just a matter of “point and click”, let alone photocopying (the analogy used in the case). Considerable knowledge and skill is required to produce a reliable image without distortion, glare or reflection, given the change in medium from canvas to film or disc.
The weakness of the case is obvious when you read the judge’s criticism of the attorney for the Bridgeman Art Library. The judge made clear that he could reach no other conclusion given the complete failure to present any evidence of the skill required to take high-quality art photographs. So the case has had virtually no impact in practice 鈥� a reflection of its flawed legal status, as well as a relief to public institutions that rely on the income from image licensing to bolster hard-pressed budgets.
Letter
The most effective recent viruses have all exploited known vulnerabilities in the Windows operating system. IT managers normally have months to patch known weak spots in their systems before a virus is written to exploit that weakness. This gives them a head start, but unfortunately prevention has to be balanced against system stability, and currently too many systems remain unpatched for too long.
A lot of the recent virus catastrophes were totally preventable. The Sobig.F worm that recently caused much damage sends itself as a .pif executable file attached to an email. Any IT professional who manages a network that doesn’t automatically filter executable files from incoming emails should hang their head in shame 鈥� there is no excuse.
The problem isn’t the effectiveness of virus scanners, it is the fact that too many networks (even critical national infrastructure networks) have terrible security systems in place, and probably aren’t even using their virus checkers properly.