Diesel delivers
Buckland points out that diesel cars may be more ecologically sound that petrol-electric hybrids. Presumably a diesel-electric hybrid would be better still.
The brain's flame
In his letter about the “hard problem”, of consciousness, Philip Cooper writes about “the neuron networks that supposedly generate consciousness” (23 October, p 28).
Why “supposedly”? The overwhelming evidence is that consciousness only arises from a material source, the mammalian brain, especially in Homo sapiens. Such a brain, moreover, must be carrying out the proper electro-chemical reactions.
Consciousness ceases to exist if you cut off oxygen or energy supplies, alter the temperature by only a few degrees, or alter or destroy its chemistry with anaesthetics, other drugs or poisons. The nature of consciousness and the personality associated with it can be drastically altered by purely material chemical means such as hallucinatory drugs. Can Cooper show us some disembodied, non-material consciousness that does not arise from neuronal reactions?
It is also misleading to consider as an example of the emergence of consciousness the difference between the static components of water (H2 and O2) and the static reaction product (H2O). Consciousness is a kinetic process arising not from static entities but from dynamic neuro-chemical reactions. So we should instead be considering the hydrogen/oxygen reaction 鈥� and from this emerges a phenomenon which we call a flame. Consciousness is analogous to flame.
Crookes's rotation
In his article on Crookes’s radiometer, Marcus Chown mentions the observation by Arthur Schuster that if the instrument’s bulb is suspended by a single fine thread it rotates in the opposite direction to the vanes, but he offers no explanation of the phenomenon (21 August, p 48).
As Chown indicates, the light itself does not transfer momentum to the vanes. So if the vanes are subject to a torque caused solely by the gas, then the gas must acquire an equal and opposite momentum in order to conserve the angular momentum of the vane-gas system. There must therefore be contra-rotation of the mass of gas.
If we now extend our system to include the bulb, its contra-rotation would seem to indicate that the movement of the gas applies a torque to the bulb, presumably via wall shear stress at the surface of the bulb associated with a boundary layer. Any frictional torque on the bulb induced by vane rotation would tend to induce the bulb to rotate in the same direction as the vane.
Badgered bumble bees
I wonder whether the lack of bumble bees in Tam Dalyell’s constituency (16 October, p 49) is linked to an increase in numbers of badgers, which dig up their nests. Since I fenced badgers out of my garden, bumble bees have become more common, and I’ve found several nests. Honey bees were rare this summer, and bumble bees were the main pollinators.
Polluting trees
Your In Brief article states: “But trees also produce VOCs (volatile organic compounds), which tend to be ignored by scientists modelling the effects of ozone on pollution” (16 October, p 18).
Emissions from trees, usually called biogenic emissions, are always an essential input in modelling urban ozone air quality. They are a fundamental source of emissions, just as VOCs from all other sources are. This has been the case for many years.
For example, trees remove ozone from the atmosphere through deposition, a process also included in ozone modelling. And higher urban temperatures increase biogenic emissions from trees, boosting ozone formation. This phenomenon can only be demonstrated through modelling specific air systems, making it difficult to generalise across all cities in the US.
Chuck the oysters
Boone Mora proposes that we produce and accumulate oyster shells to solve the problem of carbon dioxide in the air (website letters, 23 October). As I have explained in previous letters to New 杏吧原创, producing calcium carbonate from seawater actually adds carbon dioxide to the air. This is because the total reaction is: 2HCO鈭�3 + Ca2+ 鈫� CaCO3 + CO2 + H2O. Two bicarbonate ions from the seawater react with a calcium ion to produce calcium carbonate, carbon dioxide, and water.
To absorb CO2 from the air, we need the opposite reaction, which uses up calcium carbonate found in coral reefs, for example. So toss your oyster shells back in the sea to combat global warming.
Correction corrected
New 杏吧原创 is rarely wrong when correcting an error, but Nunavut is a new territory, not a province, of Canada (16 October, p 23).
Profitable wildlife
Fred Pearce is right 鈥� conservation needs money and wildlife stays if wildlife pays (23 October, p 14).
As WWF finally acknowledges the value of using wildlife wisely, the International Fund for Animal Welfare’s retrograde stance looks increasingly wrong-headed. When the IFAW devotes funding to lobbying against wise use of wildlife it perpetuates the myth of “wild” Africa, denies poor countries cash from wildlife that will anyway die from natural causes, exacerbates conflicts between wildlife and rural populations and retards development of wise stewardship of wildlife in conservation areas that are effectively protected.
The IFAW might be better to put its money where its mouth is and start facilitating wildlife conservation that does not conflict with the development interests of the citizens and wildlife of African range states.
Silicon life
Many of the limitations of life in Titan’s potential lakes of liquid methane and ethane, or the even more extreme cold of the subsurface liquid nitrogen of Neptune’s moon Triton, are only limitations if we think of carbon as the central element of life (23 October, p 42).
Star-Trekkish as it sounds, life based on silicon might be a possibility under such conditions. At the temperatures on Earth its compounds are less stable than their carbon counterparts. But the corollary of this is that they react faster at low temperature, and some of these reactions may take place in liquid nitrogen, which almost no complex carbon chemistry does. The rate at which chemical reactions can occur in liquid nitrogen or ethane is limited mainly by how fast molecules can diffuse through the liquids to meet each other, and this is not much slower than in water.
One major problem for carbon chemistry is how life could get started before enzymes have evolved if the environment is too cold for any carbon chemistry to happen. But there are plausible routes by which silicon chemistry might get started in the deep freeze of the outer moons. Silicon displays all the chemical diversity necessary to perform the biochemical functions we see in terrestrial microbes. There is a lot more about this possibility in Astrobiology (vol 4, p 137).
Diesel delivers
Colin Buckland suggests you research and publish an authoritative article on the relative merits of diesel versus petrol-electric hybrid cars (16 October, p 22). I too would very much like to read such an article. Pending its arrival, however, here is a summary of the situation as I see it.
If a hybrid does 50 miles per gallon and a diesel 60 mpg, the diesel will only emit 5/6 of the carbon per mile that the hybrid does. The carbon/hydrogen ratios in the two fuels are almost identical.
Further, the diesel will emit it all as carbon dioxide without needing a catalyst to oxidise the carbon monoxide, as a petrol-fuelled car does. And better still, if the diesel you burn happens to be biodiesel, you’re only putting back the carbon you took from the atmosphere in the first place. Diesel and hybrid cars emit similar amounts of nitrogen oxide, so both will need catalytic converters. Modern low-sulphur diesel will ensure low sulphur emissions.
The main concern with diesels is particulate emissions, but good soot filters reduce these to very low levels. If you follow a modern diesel you will notice it smells more like a good central heating boiler than a coal fire.
The hybrid also loses out when a lot of acceleration and braking is called for, because despite the advantage of regenerative braking, the hybrid’s heavy batteries make it weigh far more than the diesel equivalent, and accelerating mass costs energy. The best modern diesels, in my opinion, make hybrid technology a dead end. Modern diesels and biodiesel fuel are worth serious consideration as the way forward for road transport.
Work-life balance
Talking of women’s under-representation in the higher ranks of science, Alison George states: “Work-life balance will be the new buzzword as employers wake up to the fact that the world has moved on” (2 October, p 42). But if work-life balance is underestimated as a factor in creative productivity, then men could be affected by this just as much as women.
Let us suppose that the present overwork culture favours highly competitive males who are less concerned by their lack of home life, irrespective of whether their skills are the right ones for the workplace. In such a culture, fathers who prioritise caring for their children are just as likely to suffer discrimination in the workplace as their female counterparts.
Surely the obvious scientific approach to diversity in the workplace would be to stop categorising people by sex altogether, and to seek rounded human beings, whose home lives are not kept rigidly separate from their corporate environment?
Men and women are most productive working in a balanced mixed-sex environment without sexual discrimination. In other words, in a successful organisation the whole is greater than the sum of its parts.
Work-life balance
Women see the world from a different viewpoint than men, and that means that they frequently offer fresh ideas that bring good results.
As a woman academic, I have closely observed the masculine world of academia for over fifty years. I have often seen how the originality of women does not fit the mould laid down by men. I have heard women scholars dismissed as “crackpots” by men, or else, when their work has been judged successful with hindsight, it has been described as having been “in advance of its time”. Either way, the women get ranked below their male colleagues.
I see no hope of resolving this dilemma until the differences between men and women are brought out into the open, and tolerantly and intelligently discussed and accepted as one of the beneficial and enriching facts of life.