Bicycle zoo
In Michael Brooks’s “Easy rider” (28 May, p 44) he wrote, “it is clear that a near-perfect [bicycle] design evolved decades ago”.
Evolution as a metaphor is perhaps a little off, given that marketing, new materials and the restrictive rules of international cycling have exerted powerful “non-evolutionary” effects on the design process.
Even so, surely the path of this “evolution” has not been towards a single “near-perfect” design but, through a process more like speciation, into many different bike designs: cargo, folding, mountain, touring, recumbent, recumbent trike, Christiania trike and front-wheel-drive recumbent.
These are not tweaked road bikes, and road bikes are no more perfect than they are, any more than there is the “right” kind of Galapagos finch.
Even when speed is the key, recumbent bikes are faster due to lower air resistance. Indeed, as I ride my recumbent with its aerodynamic and comfort advantages, I tend to view traditional road bikes as being pretty imperfect.
From Jerry Cain
Your feature stated that bike riders “seem to rely on a mix of feedback controls from various inputs” and “most of the control is done by turning the handlebars”.
Perhaps the experts involved made the same discovery as me and my teenage pals in the 1930s: that crashing was inevitable if we crossed our arms on the handlebars, in other words, put the right hand on the left grip and vice versa.
Wagers were laid, but universally scraped elbows and knees precluded payment.
Try it on grass if you insist on verification.
West Lafayette, Indiana, US
Calming effect
Ocean engineering authority Chiang Mei, quoted in the story “Wave dismantler could shield coasts” (4 June, p 14), has been the voice of breakwater reason since at least 1978, when he predicted the failure of the huge breakwater in Sines, Portugal.
Wave-modifying theories, such as the invisibility cloak principle, can be adapted to water waves, but rarely where they dissipate or convert their energy 鈥� near the shoreline, for example. As Mei points out, numerical and physical modelling may prove this concept without proving its feasibility for a breakwater.
All “clever” wave absorbers have anchoring problems at full scale. The absorbed or converted energy from a wave must be resisted by forces on the foundation and anchorage of the system. These forces are small in the lab, but rise as the cube of length scale: that is, for a model scale of 1:10, the anchoring force scale is 1:1000; a kilogram in the model corresponds to a tonne full scale. That is why coastal engineers specify massive rubble-mound or caisson breakwaters.
As for tsunamis, they are long, long waves, whose wavelength is usually several kilometres. To provide effective protection, the cylinder array described in the story would need to project at least a wavelength offshore.
The mathematician proposes and the coastal engineer disposes.
Fired up
I read with concern the story on energy-related carbon dioxide emissions hitting a record high last year (4 June, p 6). It looks like Germany has just decided to focus on burning more coal and gas for political reasons. Opportunists such as the German chancellor Angela Merkel keep repeating words like “renewable” to disguise the reality, and gullible voters swallow it.
It is time to realise the fossil fuel industry has won. All recoverable coal and oil is going to be burned. We need to start mitigating the effects of climate change now, before it’s too late.
Top priorities should be the creation of migratory corridors between wildlife refuges, assisted migration of threatened ecosystems where that isn’t possible and creation of doomsday vaults for seeds, embryos and tissue samples.
At least that will give our descendants a chance to partly restore the planet, should they survive the bottleneck.
Mutual benefit
Pat Shipman’s concept of the domestication of animals by humans (28 May, p 32) overlooks the fact that it would certainly have been a two-way street.
Wolves, for instance, were not passive agents upon whom domestication was imposed. They launched themselves on this pathway because, being opportunistic omnivores, they recognised the activities of humans as providing a niche worth exploiting.
Wolves/dogs and humans domesticated each other.
Baby's blank
I read Kirsten Weir’s article on childhood memory (30 April, p 42) with interest.
It is not hard to understand why “most people remember nothing from before the age of 2 or 3”. Most things that happen to a baby are not individually memorable. Being bathed, fed, changed and put to bed belong to short-term memory; each day’s memories are overlaid by repetition and each new attainment is soon taken for granted.
Also, children are not expected to remember what went before. Most events memorable to adults are incomprehensible to a baby.
Finally, a 1-year-old has no calendar, no concept of years or months, and therefore no framework in which to fix memories.
No, sunshine
In his letter, Michael Phillips suggested a solar furnace could focus sunlight into a beam to power a plasma-engined rocket (28 May, p 31).
Unfortunately, solar furnaces cannot focus sunlight into a beam, they focus it into an image of the sun at a single focal distance. The sun subtends an angle of 0.5 degrees at the Earth, and the focused image subtends the same angle.
The rocket would rapidly reach a height where the diverging “beam” was much larger than it. This is why you need lasers: the beam remains narrow over a much greater distance.
Still steaming
The continued use of a stylised steam train on road signs warning of a rail crossing is not quite as anachronistic as Feedback would have us believe (14 May).
The reality is that there has not been a single year, let alone a decade, in which there has been no steam traction running on British main lines.
Clearly, the steam loco outline has been retained as it is instantly recognisable. Images of most other forms of rail traction would, unfortunately, look like buses.
Go with the grain
K.T. van Santen writes that both tomatoes and trees have short-term carbon cycles, but goes astray in conflating the two (4 June, p 35). Almost every carbon atom in a tomato plant and its fruit will be oxidised within a year. Trees continue to withdraw carbon from the atmosphere for as long as they are growing, which may be many decades.
Carbon fixed in wood may remain out of circulation for centuries in objects such as buildings, furniture and books. We should maximise this form of carbon capture and storage by reforesting large areas, substituting forest products for energy-intensive materials, and by reusing and recycling them.
Jungle law
Fred Pearce questions the Borlaug hypothesis (5 February, p 26), that agricultural intensification could save rainforests from further destruction to create farmland.
We cannot rely on farmers at the borders of our diminishing rainforests to voluntarily maintain the status quo.
Rich countries and the UN will have to motivate governments that control rainforests to legislate to stop farmers, loggers and others from damaging the remaining areas. Rangers will be needed to enforce this.
The world benefits from rainforests. It is reasonable for rich countries to pay for the protection of an asset which is vital for a sustainable future.
Vacuum row
Ernest Lucas sells science short when he suggests that philosophers or theologians will be able to tell us the origin of the quantum vacuum (4 June, p 34).
Suppose that science could not answer this question. Does that mean we can simply make up an answer and insist it is so? That is what theology is, after all. In what sense is that an “intellectual discipline”?
The theologians’ answer will, of course, be “God did it”. But why is there a God rather than nothing? Like petulant teenagers, the only answer they will provide is: “There just is, right?”
CC all readers
On the use of words in meanings different from the original (Feedback, 28 May), it is worth correcting the “typist’s” mistaken belief that cc stands for carbon copy, as its use pre-dates this.
It is the Latin duplication of the initial letter of a noun to indicate plurality. The Latin copia was, in medieval use, an extra copy of a land tenure document, and cc indicates more than one, as in LLB (Bachelor of Laws) and pp (pages).
Bad for bats?
Pity bats and other cave-dwelling animals if sound waves are blasted into caves in order to map them (4 June, p 26). Marine mammals are having a hard time with noise pollution in the oceans, particularly from the military; surely bats will fare little better with bangs in caves.
Grilled rat
Cedric Mims points out that rodents consume a considerable proportion of food crops (4 June, p 34). I don’t know how much of the world food crisis is caused by the African cane rat, but I do know they are delicious when barbecued. They are big and meaty and very tasty.
It’s one way of getting even.
For the record
鈥� In the “Mind readers” feature (28 May, p 40), Hans Berger’s invention was the encephalograph.