Steeper than vertical
I must comment on the Feedback piece about the vertical roller coaster (6 May). You may be interested to know that Oakwood theme park () in west Wales has just installed an even steeper roller coaster called Speed, with a “past vertical” drop of 97 degrees. I think that will satisfy your readers who ask how you can get a steeper-than-vertical drop.
From David Purchase
Climbers know well that slopes can be steeper than vertical. They can be overhanging. An early guidebook for walkers described the Inaccessible Pinnacle in Skye thus: “The drop on the west side is infinite and vertical. That on the east side is rather longer and steeper.” Having been on that summit, I can assure you that is just how it feels.
Bristol, UK
Anagram clue
I’m amazed that in the study on subliminal advertising researchers used an anagram of Lipton Ice 鈥� Nipeic Tol 鈥� for the control (29 April, p 16). Why? Well, at first glance I thought they were both Lipton Ice. Some brains work like that, especially in the first 300 milliseconds.
杏吧原创s and SUVs
Unlike many earlier correspondents, I would argue that the advertising of SUVs in New 杏吧原创 is a good thing. Look at it this way: from the recent letters, it is obvious that the intelligent and attractive readers of this magazine would never even consider purchasing one of these CO2-producing behemoths. Indeed, my hatred of the companies that sell them increases with every picture of gleaming 4脳4s perched atop rugged outcrops. Their advertising strategy appears to be failing here.
Consider now that every pound/dollar/euro spent on advertising such vehicles in New 杏吧原创 is a pound/dollar/euro not spent on advertising in publications with a less discerning audience. As members of “the enlightened”, I believe it is our duty to draw funds away from advertising aimed at the easily influenced and environmentally irresponsible.
Like can attract like
Are Simon LeVay’s observations about gay relationships favouring difference tainted because obviously different same-sex couples 鈥� such as older white man with younger Hispanic or Asian man 鈥� stand out and are thus more easily identified (29 April, p 42)? A quick look around the numerous pairs of clones in long-term relationships evident at any same-sex relationship recognition rally would suggest homosexual homophily is at least as abundant a phenomenon.
Watch your step
The message of our paper was not in fact that “if you walk around with your eyes shut you are more likely to fall over”, as Feedback claimed (29 April). We were not asking if vision was being used during walking, but specifically how and when it was used during a step. Our experiment did indeed occlude visual feedback, but only during the swing phase of a step. This revealed that vision during this phase, when present, results in corrections of foot trajectory even in a predictable environment. “Blindingly obvious”? Perhaps not. Previous research had suggested that only vision during the stance phase was significant. Our research confirmed that the path of the foot when it leaves the floor is not fixed, so vision can be utilised during this phase as well.
Cyclists' fumes
I agree with Alex Rothney that cyclists escape a great deal of traffic air pollution by reason of their higher position relative to the road, but there is another reason why they escape much of the pollution (6 May, p 25). Cyclists spend much less time in traffic jams than motorists, as with a bike it is always possible to squeeze past stationary vehicles, or even to dismount and become a pedestrian.
Furthermore, cyclists do not use the same routes as motorists: riders can use minor roads and off-road cycle lanes that bypass the more congested areas. Air pollution contributes to death from cardiovascular and lung disease, but all the evidence from cyclists indicates that regular cycling has a protective effect.
From Iain Hayes
I feel that Rothney has slightly missed the point. Even if cyclists aren’t suffering from air pollution to the same extent as other road users, it is inexcusable that they have to suffer at all at the hands 鈥� or engines 鈥� of people who are predominantly driving short distances that could easily be undertaken by bicycle or public transport.
Edinburgh, UK
Gene society
“Revolutionary” was the right word to describe Austin Burt and Robert Trivers’s new book Genes in Conflict (6 May, p 48). What is revolutionary about it is its Darwinian approach.
Hitherto, any changes in a gene have been widely visualised 鈥� certainly by the layman 鈥� as arbitrary lesions or “misprints” occurring during the process of replication. Burt and Trivers depict these mutant segments as independently evolving entities, as intent on perpetuating themselves as any other living unit. Like the dinosaurs, they appear to have had lineages that flourished and later became extinct. Their former existence and history may be deduced and sometimes even timed from stretches of inactive DNA, as the dinosaurs’ can from the fossil record.
It is a startling idea. Reviewing it in Nature, James F. Crow was unable to swallow it whole. Agreeing that this approach makes the book especially interesting and stimulating, he acclaimed it as “great, if you don’t inhale”. However, it is very cogently presented, and ultimately we may find that we have to inhale.
The Nature review also recalled how Trivers’s papers in the early 1970s met with opposition from social scientists and Marxists 鈥� but these new revelations are unlikely to attract similar criticism. Those who like to think that human behaviour is dictated by “algorithms all the way down” will hold to that belief, but others may feel there is something liberating about the picture of a seething underworld of genes with conflicting interests. It seems to give the organism more room for manoeuvre than the monolithic single-minded activator which the words “selfish gene” have sometimes conjured up in the popular imagination.
Legal drug pushers
It was encouraging to see an editorial on the subject of disease-mongering and to read the views of David Healy (15 April, p 5 and p 38). It seems to many of us in general medical practice in the UK that the bewildering helter-skelter of change to which the National Health Service is being subjected is largely driven by the drug companies. The resulting exponential rise in drug costs means that increases in health budgets are not translated into predicted health improvements, something that politicians seem unable to comprehend.
The new GP contract specifically pays us for escalating drug spending, moves us away from a patient-centred agenda in consultations, detracts from our ability to make individual decisions based on experience and negotiation, and promotes the concept of disease-mongering at the expense of disease avoidance. Are any policy-makers out there listening?
Disrespecting the dead
In today’s tradition of seeking the ultimate sideshow, we now hustle the family on down to the local science museum and plunk down our Visa card for admission to view the flayed and dissected remains of fellow humans, frozen into “artful” poses, caught in the act of kicking a soccer ball, or split down the middle as with a meat cleaver (6 May, p 51).
Respect for the dead has been a defining characteristic of human culture from its inception, but no longer. Such respect has been demonstrated throughout recorded history by the ritual love and honour shown to those who had died, as displayed in funeral traditions and elaborate grave sites. The exception has been the treatment accorded to one’s enemies: corpse mutilation was commonly a way to exhibit vengeance and has in recent years come to be regarded as so abhorrent as to have been outlawed as a war crime by the Geneva conventions.
It is also a crime to “pillage” a body. How much more pillaged could a body be than to be hacked up and displayed in public for financial gain?
Taking liberties
Zeeya Merali’s provocative article may have left readers with the impression that our paper “The Free Will Theorem” was a response to a recent paper by Gerard ‘t Hooft. In fact, neither paper was written with knowledge of the other. Also, the title of Merali’s article “Free will 鈥� you only think you have it” (6 May, p 8) is exactly contrary to our own opinion.
Our theorem emerged from a long study of the “twinned Kochen-Specker paradox”, not examination of ‘t Hooft’s paper. We drew no “potentially frightful consequence” from his work, but showed with mathematical precision that the opinion of most physicists that particle behaviour is indeterminate is a consequence just of the free will of the experimenter and three simple physical axioms.
More contentiously, since we have never seen any reason to doubt human free will, we expressed our personal happier beliefs: “The world it presents us with is a fascinating one, in which fundamental particles are continually making their own decisions. No theory can predict exactly what these particles will do in the future for the very good reason that they may not yet have decided what this will be!”
From Rick Fielder
Merali says that with quantum uncertainty we can’t have free will, but doesn’t mention that unpredictable behaviour can come from other places as well, such as chaotic systems. This can only be predicted by running an exact simulation, which would be identical to just watching the universe evolve.
It follows that in our universe the only way to predict what is going to happen is to sit back and watch. So even if we don’t have free will we can’t actually tell.
Didcot, Oxfordshire, UK
Is anything imaginary?
I never imagined being in a position to comment on Stephen Hawking’s ideas about quantum properties of the cosmos and imaginary time. I am doing so now because your article mentions that electrical engineers routinely use complex numbers to design electrical circuits, as though this somehow might make the concept of imaginary time acceptable (22 April, p 28).
We do use complex numbers a lot, but only as a means of solving what would otherwise be horribly difficult trigonometry problems. Voltages and currents of the same frequency are represented by coplanar vectors, and these are overlaid with an Argand diagram so that the vectors become complex numbers. Dividing voltage by current gives a complex impedance with real part (resistance) and imaginary part (reactance). Multiplying voltage and current gives a complex power with real power and imaginary power components. I hate some of these names but we understand exactly what they mean. Frequency, time and everything else in electrical engineering and, come to think about it, everything else in science, is real, and we should not forget it.
My company has a 拢1000 prize awaiting the first person who can name anything that is indisputably imaginary in science, excluding mathematics. Terms and conditions apply. See .
Too risky to ignore
David Healy claims that suicidal acts are 2.2 times as likely in people who take mood stabilisers, compared with those taking a placebo, based on data from clinical trials (15 April, p 38). However, the figures he quotes indicate that the difference in likelihood of suicidal acts by those taking placebo compared with those on medication is not statistically significant. That being so, how can he use these figures to draw any conclusion on the possible link between mood stabilisers and suicide?
David Healy replies:
鈥� I accept that the risk of suicidal acts is not statistically significant according to the conventional standard, which requires 95 per cent certainty. In this instance, an odds ratio of 2.2 means there is a 65 per cent certainty that the higher suicide rate is due to mood stabilisers rather than to chance. Establishing a safety risk with 95 per cent certainty is an incredibly high standard to demand, and would often require impossibly large studies. This issue was highlighted by David Graham, a researcher at the US Food and Drug Administration, in his testimony to Congress regarding the agency’s failings concerning Vioxx and SSRIs.