Nuclear matters
Just as the nuclear industry was on the brink of a renaissance, along comes the disaster at Fukushima (19 March, p 5 and p 8). Anti-nuclear campaigners now have serious grist for their mills.
There are, however, two courses of action for the nuclear industry that should make nuclear power a serious “green” option for all but the most diehard opponents.
First, switch nuclear fuel from uranium or mixed oxide with plutonium (MOX) to thorium. As New 杏吧原创 has reported (26 March, p 8), no meltdowns are possible, no fuel enrichment is required and the radioactive waste is very short-lived. Thorium reactors were abandoned by the nuclear industry during the cold war because they could not be used for breeding fissile materials for nuclear weapons.
Secondly, build reactors deep underground. This solves two problems at once: containment and decommissioning. It also makes it easy for each reactor to be built with a large water reservoir above it for passive emergency cooling, employing gravity and not pumps 鈥� which failed at Fukushima. At the end of its design life, the underground installation can be sealed, complete with its complement of spent fuel.
From Hugh Colvin
The weakest link in the nuclear power chain is not so much the technology as the human beings involved in foisting it on us, who are frequently secretive, ill-prepared and short on logic.
You state that Fukushima “was shaken by a megaquake that was exceptional even for Japan” (19 March, p 5). This tsunami was exceptional only in the subjective terms of the human lifespan, not in the statistical terms which should be the objective measure used by scientists and risk managers. It has been described as a once-in-1000-years event; a similarly large event hit Japan in AD 869. Reactors are built to operate for perhaps 40 years. The crudest of calculations gives you rough odds of only 25:1 against the nuclear disaster we are now witnessing.
You say that Chernobyl “pales into insignificance compared with the devastation earthquakes and hurricanes inflict”. But it permanently displaced about 135,000 people, and 25 years later there is still a 30-kilometre exclusion zone around it. New Orleans has had a difficult recovery from hurricane Katrina, but five years later 70 per cent of the population has come back.
Llanfair Waterdine, Powys, UK
From Ian Christmas
Those who are trying to play down the risk of nuclear energy are not fully representing what the term “risk” involves.
There are two independent elements: probability (how likely something is to happen) and seriousness (how damaging it will be if it does happen). All too often it is reported that something is “low risk”, when what is meant is “low probability”.
Hughenden Valley, Buckinghamshire, UK
From Robert Findlay
Nuclear reactors are superb military targets. While there may be international conventions prohibiting the deliberate bombing of nuclear reactors, revered international conventions applying to the treatment of civilians, so-called “armed combatants” and other people fighting for their country have been ignored repeatedly by assorted nations during the past 100 years. Why should it be any different when it comes to attacking reactor sites?
We may manage to build a near-foolproof nuclear reactor, but none can be made war-proof.
Montagu Bay, Tasmania, Australia
Lazy time
You point out that GPS is an essential element of some critical systems such as air traffic control (12 March, p 3 and p 44). There is, however, no need for cellphone masts and ATMs to rely on GPS. They both have easy access to high-bandwidth fixed line networks that could provide accurate time for synchronisation and auditing purposes. Lazy system design is responsible.
Morality without God
Martin Nowak is right to say that “Evolution is not an argument against God” (19 March, p 34). It is, however, a powerful argument against the literal truth of the Bible, the Koran and any other book that asserts a creationist position 鈥� and many religious people base their faith on the literal truth of their holy books.
Happily for us all, we probably do have a global majority for being nice. Most religious and ethical traditions support it and most individuals try to practise it most of the time.
Humanists agree with Nowak in seeing religion as a developing set of tools for managing our social and political life. Principles such as compassion may draw strength from religious endorsement, but they do not depend on it.
From David Jenkins
If you pick two random humans and compare their genes, they are likely to be much more similar than those of two chimps picked at random out of the same group, a paper in Science () reported in 1999. This is evidence that within the past couple of hundred thousand years humans have been through a major genetic bottleneck. Might that explain the roots of our cooperative nature?
Carlton, Bedfordshire, UK
Digital evolution
Your excellent piece on the evolution of humans and how civilisation has shaped us (19 March, p 36) reminded me of a great test for membership of the baby boomer generation: ask the test subject to press a doorbell.
Those of us born before mobile phones and handheld consoles almost always use our index finger; those from “generation Y” almost universally use their thumb, having spent their life using it to text and control games.
It is interesting that something so seemingly trivial can seemingly overwrite millennia of evolution in such a short time. More importantly, it provides a simple excuse for my constantly losing at any console game: I was born too soon.
Random vitamins
The effect of vitamin D on the speed at which certain drugs are broken down (12 March, p 13) may be particularly significant for warfarin, a drug for which it is notoriously difficult to calculate the appropriate dose.
Your article mentions only sunlight as a factor in vitamin D levels. But many people take supplements which contain vitamin D, and that too needs to be taken into account. People may not worry about maintaining a regular intake of a tablet they take voluntarily, and miss doses at weekends, on holiday or if they run out. If the amounts taken vary significantly and sharply, it will be hard to calculate their effects on other drugs.
Dream substitute
Reporting on dream research, Emma Young mentions Matt Walker’s view that dreaming is important for “rebalancing the emotional compass” (12 March, p 36). Walker’s finding that sleep strengthens certain emotional memories might be seen as support for the use of eye movement desensitisation and reprocessing (EMDR) as a therapy for post-traumatic stress disorder (3 February 2007, p 40).
It seems conceivable that in people with PTSD, the specific eye movements that take place while recalling disturbing memories in EMDR might make up for the dreams’ failure to strip away emotion.
From Tim Stevenson
So possible purposes for dreaming include rehearsing our response to a real-life threat. May the rehearsal hypothesis be taken further, at least in the case of daydreaming, when introspection is possible?
Beyond the totally routine, we think too slowly to identify the optimum response to any situation from scratch. This is an unavoidable consequence of the mental evolutionary arms race our species underwent. Instead, we rely upon a vast mental repertoire of situations and appropriate responses. We are slow to reach social maturity because of the time it takes to develop such a good stock.
Daydreaming certainly, and possibly dreaming while we sleep, allow us to expand our repertoires by pondering our responses to imaginary situations.
Prestwood, Buckinghamshire, UK
Other attraction
I loved Helen Thomson’s wonderful article on what prompts attraction at first sight, and I imagine that men have since been rushing out to buy red shirts (12 February, p 36).
I do wonder if this applies to the gay and lesbian worlds. It would be interesting to know whether there have been similar studies of their response to coloured clothing.
Wrong rhino
In the “Instant expert” guide to mass extinctions, your description of how woolly rhinos and mammoths died out 11,000 years ago was accompanied by two pictures (5 March, p ii). One correctly showed mammoths, but the other is not the two-horned woolly rhino (Coleodonta antiquitatis) but the much larger Elasmotherium sibiricum, which had a shorter face and a single horn up to 2 metres long extending from its forehead. It apparently became extinct at the end of the middle Pleistocene, long before the woolly rhino took its final bow.
Vulcan's hatchling
If that’s a “gushing larva” in Iceland, as your picture caption indicates (12 March, p 43), I’d hate to see the adult!
For the record
鈥� While the text in our “Instant expert” pull-out guide to dark matter (5 February) said that the Z boson transmits the weak nuclear force, the caption on p iv said otherwise. The caption was incorrect.
鈥� In a bungled attempt at clarification of a letter by Valerie Yule about using concert technology to help older people discriminate dialogue (19 March, p 33), we added a sentence saying that compensating for the difficulty of picking out voices from low-frequency background noise “often requires that the radio or television be turned up to a level unpleasant for younger ears”. She points out that “Turning up the volume only makes the noise louder for older ears”. Our apologies for the error.