Protection, for whom?
Your special report on nanopollution contains a misleading caption (29 March, p 14). The use of multimillion-dollar clean-room facilities and protective masks and clothing doesn’t spring from the need to protect researchers from nanoparticles, but to protect nanoparticles from researchers. Stray dust, hair or moisture from a person can spell disaster for nanoparticles or even for conventional semiconductor materials.
Not godlike yet
In referring to Stephen Hawking’s view that physics, like mathematics, may contain true but unprovable statements, Michael Brooks writes that this is something “we might have seen coming for decades” (5 April, p 34). Perhaps this is a point on which philosophers were ahead of physicists.
In Unended Quest (1976), Karl Popper wrote: “The evolution of physics is likely to be an endless process of correction and better approximation. And even if one day we should reach a stage where our theories were no longer open to correction, since they were simply true, they would still not be complete 鈥� and we would know it. For G枚del’s famous incompleteness theorem would come into play: in view of the mathematical background of physics, at best an infinite sequence of such true theories would be needed in order to answer the problems which in any given (formalized) theory would be undecidable. Such considerations do not prove that the objective physical world is incomplete, or undermined: they only show the essential incompleteness of our efforts.”
Letter
In the first paragraph of his article, Michael Brooks repeats a common distortion of Stephen Hawking’s views. Hawking doesn’t think that we would “know the mind of God” if we invented a theory of everything. Instead, he thinks that such a theory would be just the first step.
On the last page of A Brief History of Time, he writes: “However, if we do discover a complete theory, it should in time be understandable in broad principle by everyone, not just a few scientists. Then we shall all, philosophers, scientists, and just ordinary people, be able to take part in the discussion of the question of why it is that we and the universe exist. If we find the answer to that, it would be the ultimate triumph of human reason 鈥� for then we would know the mind of God.”
Hawking doesn’t think that physics gives insight into the mind of God. Indeed, he explicitly states that science can’t answer the question of what “breathes fire into the equations and makes a universe for them to describe”. This, he believes, is a job for philosophers.
'Cold fusion' explained
Your article on cold fusion (29 March, p 36) as well as the review of the book Undead Science: Science studies and the afterlife of cold fusion by Bart Simon (22 March, p 48), omit a simple and known explanation of the extra heat given off by metal hydrides such as palladium deuteride.
The extra energy comes from elastic relaxation. When hydrogen is forced into the metal, either by external pressure or by electrochemical means, the metal lattice swells to accommodate it. The new lattice is irregularly distorted and full of defects.
People who work with hydrides tell me that if you touch a block of palladium hydride, you will feel your hand grow warm. Apparently the readjustment of the solid structure goes on for months, and as the potential energy decreases, the liberated energy is radiated out as heat and conducted away.
Made in space
Presumably the problem of the extra launch weight of cooling water (29 March, p 21) disappears if the water is generated as a by-product of the fuel cells during the mission itself (22 March, p 37).
Mum's the word
Tam Dalyell points out that having babies makes it hard for women to progress in science (5 April, p 53).
That sounds like indirect sex discrimination to me. Perhaps Britain’s academics should be reminded of the law. Ambitious women with maternity gaps in their CV might like to look at:
Watery solutions
Does the solution to the world’s water supply problems have to be “either or”? If even the present human population is to be supplied with enough water, both dams and rainwater harvesting are likely to be required 鈥� in different places or in the same places at different seasons (22 March, p 11).
You are here鈥�
Feedback’s correspondent Chris Collins points out the redundancy in a promotional document reference number (29 March). The 35 letters and five numbers of the mailing address for New 杏吧原创 (New 杏吧原创, 151 Wardour Street, London W1F 8WE) could specify your position on the Earth’s surface to an accuracy of 1 nanometre, with enough redundancy left over to deliver the letter to an individual cell in the body of a selected staff member. If the staff member’s name is included in the address, the letter could be delivered to an individual atom in their body (still with some redundancy left over!).
The calculation is simple enough, but if you want more detail please send correspondence to the third neuron on the left in my cerebral cortex.
Shut that door
Here is a solution to Feedback’s dilemma over the fire hazard posed by automatically closing doors being wedged open (29 March): prop the door open with the nearest fire extinguisher. Should a fire break out, the extinguisher will be removed for use, enabling the door to close.
For the record
鈥he physiotherapist who led the research on using textured insoles to reduce injuries is Gordon Waddington of The Canberra Hospital. Apologies for getting his first name wrong in our story (5 April, p 15).
鈥n our feature on Biotech in Britain (12 April, p 54), we mistakenly relocated Alizyme Therapeutics to Abingdon, Oxfordshire. It remains, as ever, in Great Abington, Cambridgeshire.
鈥teuart Campbell’s letter on the nuclear fuel cycle stated: “In fact, 98 per cent of the ‘used fuel’ is recovered in this way” (12 April, p 29). This figure should have been 96 per cent.
After the battle
I was initially surprised that Lewis Moonie (5 April, p 28) should be naive enough to believe that there can ever be such a thing as an independent report on matters as politically sensitive as British and American forces leaving depleted uranium scattered across Iraq.
However, careful reading of his letter reveals an evasive use of language. He writes, “Many independent reports have been produced that consider the battlefield effects of using DU munitions. None of these has found a connection between DU exposure and illness鈥�”. But it is not the “battlefield effects” that we are particularly worried about, rather the long-term effects of this stuff on the environment.
Similarly, he quotes two Royal Society reports which state that, “The inhalation intakes from resuspended DU are considered to be unlikely to cause any substantial increase in lung cancer or any other cancers.” Apart from the obvious questions (How unlikely? What is substantial? Who decides and in whose interest?) inhalation is by no means the only route by which people can be contaminated by DU. Nor is cancer the only possible effect.
Forestry threat
The World Bank is indeed in a regressive phase. Not only is it promoting large dams again (22 March, p 11 and p 29), but it is also back into logging primary forests.
Last year the it overturned a 1991 forestry policy that prohibited funding of logging in primary moist tropical forests. Its new policy allows it to finance projects which destroy all but “critical” forests 鈥� officially recognised protected areas and sacred sites.
Non-governmental organisations consulted by the World Bank had urged the opposite: that the proscription on funding logging be extended to cover all old-growth forests. This was because the World Bank finances projects in Russia, which boasts 22 per cent of the world’s forests but where old growth is under serious threat.
The World Bank also refused recommendations from its technical advisory group that the policy should require borrowers to comply with the international human rights treaties ratified by borrower countries. This has sent a shiver of fear through the forest peoples who stand in the way of forestry corporations.
Gambling in the fields
Your three-way debate about genetically modified crops raises a number of issues that need to be addressed (5 April, p 44).
First, Chris Leaver and Anthony Trewavas ask, “If we replicate by genetic engineering what nature has already done, are we really doing anything different?” But scientists are not at all replicating nature. In our view, genetic engineering techniques are very different from natural processes and that’s the problem.
Nor do we think genetically modified organisms are rigorously tested for safety. They are tested far less than pesticides that we still believe could be having undetected long-term effects. You cannot extrapolate results from controlled lab conditions or even controlled field trials to the wider environment and human body. Ecosystems and health are complex, and all sorts of new stresses and interactions come into play which mean that in our view you cannot predict the actual impact of GMOs from the limited tests currently used. This concern was raised by the many scientific advisers who opposed the US government’s GM approval procedures, but unfortunately they were ignored.
We also think it is wrong to say GMOs have had no negative effects. Many people claim they have suffered allergic reactions to the GM StarLink maize in the US 鈥� some serious. There are no other reports of negative effects, simply because no one in the US has studied the health effects of eating GMOs.
HRT safety
Marina Delac makes the argument in her letter that hormone replacement therapy based on the two hormones oestrogen and progesterone might be safer if women took the natural “bio-identical” hormone progesterone instead of the synthetic progestins usually prescribed (29 March, p 29). But as she correctly points out, the bio-identical progesterone preparations that are available have never been tested in large-scale trials, so no one knows whether they are indeed safer.
I have come across one trial done in 1998, but the results were not convincing. To be effective, progesterone or its synthetic equivalents must reach and protect the uterus to prevent it turning cancerous through overexposure to oestrogen. But when the bio-identical progesterone was applied to the skin as a cream, not nearly enough diffused into blood to protect the uterus. This is hardly surprising, given that the skin contains 5-reductase, an enzyme which destroys progesterone.
Unless a way can be found to make bio-identical progesterone as resistant to enzyme destruction as its hardier synthetic cousins, it looks as though the commercial preparations are the only reliable ones for now.