Conversion to clay
Both Graham Hodgson and Boyd Williamson (Letters, 4 March) detected an apparent inconsistency between the immobilisation by clays of the DNA and amino acid precursors for life (18 February, p 7) and the idea in Jeff Hecht’s article (11 February, p 15) that clay production would have been minimal before the appearance of life because physical weathering would not have produced particles “fine enough to form clay”.
Hecht implied that life, whether microbial or fungal, is necessary to convert rock-derived material to clay minerals (a process of chemical weathering) with the high surface areas and often electrical charges that make them so effective as adsorbents (as in kitty litter). However, the conversion of reactive rock minerals such as feldspars and micas to clay minerals is a purely inorganic reaction. It usually occurs by precipitation of dissolved components of the reactive rock mineral. Their dissolution is greatly aided by a low pH, so it is only necessary that there be a source of acid.
Since the advent of life, its ubiquitous production of carbon dioxide has provided widespread low-pH waters for rock mineral dissolution. Nonetheless acids were present from inorganic sources long before the appearance of any forms of life, with volcanic eruptions a significant source. Chemical weathering of rock minerals to give clay minerals has always been with us.
Working water
Peter Abrahams (Letters, 11 March) raises the question of how much water would be required to produce hydrogen for fuel by farming algae, in response to the 25 February articles “The parched planet” (p 32) and “Green gold” (p 37). While I do not have the figures to answer this question, I have made a calculation on hydrogen production by bio-fermentation, which might prove illustrative. To replace the 54 million tonnes (and rising) of petroleum fuel currently used annually in the UK would require 1.78 脳 1011 cubic metres of H2. To produce this amount would need a total volume of 152 cubic kilometres of fermentation vessels, which is rather more than the entire reserve of freshwater available in the UK (148 km3), assuming we had no other need for it. To grow the sugar crop for fermentation would require around 520,000 km2 of land, which is more than twice the entire area of the UK mainland (most of which, of course, is not arable). The waste, mainly butyric acid (essence of sweat) and acetic acid (raw vinegar) produced would amount to around 400 million tonnes, or more than sufficient to fill Lake Windermere…and that is every year, in perpetuity. The details of these and other calculations on meeting future fuel requirements by renewables, nuclear etc are available at: , which your readers might find interesting.
From Malcolm Shute
You have now published two letters, in successive weeks, in which the writers point out that the vast quantities of water poured on to agricultural crops are not lost, but remain on the planet (11 March, p 22, and 18 March, p 24).
This is true, but misses the point made in the original article, namely that useable water is being squandered, despite it being in short supply. In effect, we can say that all natural resources are provided for free, but that it costs time and effort to collect them. Solar energy pours down on us for free, but what makes it expensive is the equipment needed to collecting it, and this is no different to the situation with coal, which is lying in the earth for free, but collecting it incurs mining costs.
In the case of water, when it is sprayed over one farmer’s fields, the majority is dispersed back to the water cycle, and cannot be reused unless we go to the cost and effort of collecting it together again. It is in our ability to collect it that we are rapidly running up against our limits, not in its availability on the planet (which has oceans full of the stuff).
La Tour d’Aigues, France
Kids' hipporoo kits
Rick Fielder asserts that Freeman Dyson’s comparison of biotech with computers is nothing to worry about because children’s games do not yet involve the construction and programming of computer systems (Letters, 18 March). It seems he has overlooked Lego’s Mindstorms product, which may well be what Dyson had in mind. This allows children, and quite a few adults, to build robotic systems that react to input from sensors. At the heart of the system is a brick containing a computer and a programming system designed for children to use. This product has been available since 1997 and a significant upgrade will be released later this year. Personally, I am looking forward to building my own hipporoo from a kit aimed at children in the not too distant future.
Pre-Inca stopover
Emma Young, in the article on hill arts in South America, points out that the most common figure, a double outlined square, is interpreted as a “ritual corral” (18 March, p 16). Could another explanation be that they are genuine corrals? As they are often found close to water, could they have been used as somewhere to park the stock for the night?
Reversed image
Daniel Fischer proposes that a correct view of the full moon be shown (11 March, p 22). Most published photographs taken from Earth are, to my Antipodean eyes, upside down. How about some inclusiveness here too?
And what about the standard movie shot of the setting moon always moving down to the right? If you’re in the south it moves to the left 鈥� and so does the sun.
Ads for gas guzzlers
The 25 March issue of New 杏吧原创 had four full-page advertisements for cars. The vehicles comprised three “gas guzzlers” (a 3.7-litre Mercedes, a 3-litre Subaru and a 4.2-litre supercharged Range Rover) and only one “green” car 鈥� the hybrid Toyota Prius. The gas guzzlers do an average of 9.8 kilometres per litre (23 miles per gallon) on the combined cycle whereas the green car does some 28 km/l (65 mpg). The gas guzzlers spew out an average of 304 grams of carbon dioxide per kilometre, whereas the green car emits some 104 g/km.
Presumably car manufacturers choose which publications carry their advertising based on the likelihood that readers will buy their product. This would imply that scientists prefer gas guzzlers to green cars in the ratio of 3 to 1, so who says that scientists are generally environmentally conscious individuals? Or is this tactical advertising a cunning ploy by the manufacturers to discredit those who raise awareness of global warming?
From Mike Wootten
Your penchant for promoting high-polluting vehicles and even higher-polluting air travel hardly gives you the right to pontificate to policy makers around the world.
Wirral, Cheshire, UK
The editor writes:
鈥� Several readers have noted the difference between our editorial line on climate change and some of our adverts. At New 杏吧原创, there is a Chinese wall between editorial and advertising. This works both ways. While it does create contradictions at times, it also ensures New 杏吧原创‘s editorial independence from commercial considerations 鈥� other than the interests and enthusiasms of our readers, of course. This is a strength, not a weakness.
New 杏吧原创‘s journalists report evidence from rational studies and write editorials based upon that evidence. We hope that these articles will help readers to make wise choices when buying technologies that increase carbon emission.
Two souls, one body
Alison Motluk reports in the box “When does life begin?” in the discussion of abortion that there is a question over whether a “soul” assigned at fertilisation might have to be split in the case of identical twins (18 March, p 8).
It gets even more interesting than that, in the case where two separate fertilisations that would normally become fraternal twins instead fuse to produce just one embryo, leading to chimerism in the adult. Here you must perforce have two “souls” inhabiting one individual.
I’d like to see the governor of South Dakota sort that one out, and I’m not sure what the Pope would think of it either.
Interest deficit
I was intrigued to read in your article on human evolution that a gene associated with attention deficit hyperactivity disorder has been selected for and is increasing in the population, though it is not known why (11 March, p 30).
One thinks of ADHD in children as a problem. I think it is only a problem when they don’t know what to do with their abounding energy. The deficit of attention is in the attention paid to what adults want them to do. I suspect such children can become highly productive and motivated people once they find a satisfying direction in which to use their abilities. It would be interesting to trace the adults who suffered ADHD as children 鈥� comparing those treated with Ritalin and those not 鈥� and see how well they are coping with life now.
Who needs gravitons?
Why does gravity need a particle (18 March, p 32)? If the theory of relativity is even partially correct then surely there can be no particle. Relativistic gravity is dependant on the curvature of space or time directly, so it needs no particle. There is also at least one theory of gravity based on “hyper-spaces”, which needs neither spatial curvature or particles because gravity becomes a direct emergent property of space. The simple truth is that these ideas of “quantum” gravity are very probably on completely the wrong track.
From Adrian Smith
Your article asserts that the force-carrying particles (excluding the graviton) are more than theoretical flights of fancy, and that experiments have detected them (18 March, p 32). I would agree with respect to the photon and the weak force bosons, but I was unaware that any gluons have ever been detected. Their sister particles, the mesons, have been detected, but no gluons have been detected on their own.
Addingham, West Yorkshire, UK
Dusting off the archives
Heather Constance is right to challenge Feedback’s image of “dusty libraries” but I must in turn challenge her suggestion of “dusty archives” (25 March, p 25).
The archiving profession has been trying to shake off this clich茅 for some years. Any properly-run archive will be managed by “well-educated, well-qualified people” like the librarians Constance describes, helping a wide range of researchers to make use of the information that is stored in their collections. Simple good housekeeping is a fundamental part of a document conservation plan aimed at ensuring that such information, whether it be hundreds of years old or last week’s electronic records, will remain usable long after its creators have turned to dust.
Nuclear longsight
I am troubled by one thing in your article on permanent waste disposal: the timescale involved surely invalidates some of the audacious assumptions that underpin such projects (4 March, p 38). Climate change and the rise and fall of nations 鈥� for which there are arguably no effective countermeasures 鈥� are two factors guaranteed to occur during the 100,000-year period described.
The designers of these repositories should also plan for the sites to be “relocation-ready”, so that when conditions change, as they will, the cost of doing this is minimised.
In just a few hundred years our descendants will start looking at using their various space elevators as a cheap, efficient means of sending Earth’s most hazardous material on a one-way trip to the sun. A bit of forward thinking when designing repositories (multiple shafts, redundant access points, transportable containers) will put them in a better position to clean up our nuclear mess.
Synroc edges ahead
Your correspondent Rosemary Campbell asks what happened to Synroc, the Australian project for sealing radioactive waste (25 March, p 25). I reported on the continuing, albeit slow, progress of this project in an episode of The Science Show on ABC Radio National a few months ago. There is a transcript at .
Space sickness
Although extremely thorough and well written, Hazel Muir’s article ignores what I would consider the more fundamental challenge to a manned journey to Mars: the physical safety and integrity of the astronauts (11 March, p 34). Humans have evolved to live and thrive with the force of one full Earth gravity. Living in a microgravity or zero-G environment for any length of time leads to the human body breaking down. By the time the crew got to Mars they would be in no physical shape to explore the Red Planet.
The other physical barrier to extended space travel is solar and cosmic radiation. Not only will a Mars vehicle have to include a rotating component to mimic at least fractional gravity, it must be encased in sufficient shielding to prevent the crew’s DNA and internal organs suffering radiation damage. Until these problems are solved there can be no successful flight to Mars or any other distant body in space.
Heated debate
Last year, US Representative Joe Barton, Republican Texas, wrote to three reputable climate scientists and asked for the facts underlying their hockey-stick theory of global warming. This request exasperated a crowd of onlookers comprised of journalists, congressmen and others, and they responded with rhetoric so hot you could fry an egg on it. New 杏吧原创‘s editorial and story only hinted at the tone (18 March, p 5 and p 40).
If I have any complaint with either, it’s that we’re being gently advised to change a position that we don’t hold. Let me clear up what we think we know and don’t know. For starters, we know the globe is warming. We know the hockey-stick graph asserts a plausible cause, but we also know that its underlying statistical analysis is said to be unreliable. A panel of statisticians is looking into this now, and a group assembled by the US National Academy of Sciences is also examining the theory, though evidently without much focus on statistical underpinnings. Finally, we know that all of us have an obligation to tell the truth, and some of us have an added obligation to the taxpayers whose money is proposed to be spent in great gobs.
For us, the process of getting to the facts began with asking for information from the people who said they had the answers. As you may have noticed, scientists tend to be proud of their work and downright eager to explain it, and it looks like the three climatologists are no different.
Not everybody is interested in listening, though. Our questions from the committee produced orchestrated anguish, the theme of which was to forget facts and just get on with the spending. Two US representatives, New York Republican Sherwood Boehlert and California Democrat Henry Waxman, share that view and heatedly instructed us to adopt it.
Representative Barton is hardly likely to accept such advice, nor should he. We don’t know what this inquiry will find except facts, and we hope and expect they will speak honestly, calmly, and for themselves.
From Nick Reeves, Chartered Institution of Water and Environmental Management
Quite rightly, your editorial promotes the reality of global warming and urges us all to deal with it. Sadly, as long as there are still those in the science community and elsewhere who are in climate change denial, certain governments and sections of the public will continue to do nothing. Conflicting advice and prevarication will be used as a reason to avoid making difficult lifestyle changes and setting more challenging targets.
Successful and urgent action on climate change is as much about marketing and presentation as it is about the science. But as any marketing-monkey will tell you, the message from scientists must be clear and unequivocal. Unfortunately, we are still far from a consensus view. Or, if there is one, it is not coming across and arguments about graphs and predictions are confusing the public and the decision-makers.
London, UK
From Brian Adams
You say, quite rightly, that the evidence for global warming is all around us but don’t mention the “elephant in the room” in front of us 鈥� economic growth.
Liss, Hampshire, UK