Wheely good odds
In your exploration of chance, you state that the probability of 26 consecutive black numbers in roulette is 1 in 136,823,184, and mention this happened in Monte Carlo in 1913, as if that was somehow surprising (14 March, p 28). What is surprising is that this doesn’t happen more often.
There are some 3500 legal casinos worldwide. If we assume there are only two roulette wheels in each casino on average, that each is only used for 6 hours a day and spun 35 times an hour, then each year we see 537 million spins.
If a black followed by 25 more blacks should happen once in every 137 million spins, it should happen somewhere on the globe every three months.
Either the probability calculation is flawed or we have just uncovered a significant bias in the world’s roulette wheels.
London, UK
Wheely good odds
Regina Nuzzo suggests that choosing between Bayesian and frequentist methods of probability is “horses for courses” (p 38). Like choosing to get home by taking the Bayesian bus or the frequentist train; both will get you there, but via different routes. It is not so.
In essence, a Bayesian estimates the probability that a hypothesis is true based on observed data values. In contrast, a frequentist estimates the probability that data values, equal to or more extreme than those observed, would occur, based on the assumption that a null hypothesis is false.
As Harold Jeffreys noted, one result of this convoluted reasoning is that, “a hypothesis that may be true may be rejected because it has not predicted observable results that have not occurred.” Bus or train? That depends on where you want to get to.
Sheffield, UK
Under covers
Sumit Paul-Choudhury’s interesting review of The Nether (14 March, p 44), a play which examines the morality of a virtual clubhouse for paedophiles, got me thinking.
What about books with content that I find horrible and offensive? If people are to be prosecuted for their imaginations, and for indulging in their fantasies in a way that does no harm to others, where do you draw the line between a computer’s virtual reality and a book’s virtual reality?
Do we revert to the times when books were banned for their content? People will always use their imaginations, in private if not in public, so the best we can probably hope for is to channel any potentially harmful thoughts in ways harmless to others, only prosecuting if it can be shown that such bounds have been exceeded.
Surely censorship should be for the guidance of the user and protection of unwilling participants, not to impose the moral standards of some people onto everyone else. The long shadow of fundamentalism looms in that direction!
Temple Sowerby, Cumbria, UK
Getting ahead
I read the various comments on proposed head transplants with interest (14 March, p 54). Even if such transplants are desirable and the spinal cord can be successfully reconnected, no one has mentioned the autonomic nervous system. Parts of this run outside the spinal column and are important in regulating a variety of internal processes including heart rate, constriction of the airways in the lungs, assorted gut activities and bladder function.
If the vagus nerve or the chain of sympathetic ganglia are severed and not reconnected, such autonomic functions may be disrupted. The relevant fibres are smaller and presumably less easy to rejoin than the spinal cord. Is this likely to be another technical difficulty?
Grange over Sands, Cumbria, UK
Getting ahead
Helen Thomson’s article on head transplants was exciting stuff. I generally feel the stir of a good debate to be quite healthy.
Surely though, in line with current transplant procedures, in which the new body part is featured in the title of the operation 鈥� heart, liver, kidney, etc 鈥� the proper name for Sergio Canavero’s procedure should be a body transplant.
London, UK
Virtual performance
Jacob Aron’s article on the new generation of virtual reality (VR) equipment focuses on its use in films or games (7 March, p 20). As the article notes, this can cause problems: in the case of games, the viewer can’t see his or her controller, and in the case of films, he or she doesn’t know what to focus on and the film equipment is hard to hide.
Why not instead use VR for live performances such as rock gigs, theatre showings, opera, sports games and so forth? In all those cases, the focus of attention is one particular area, and the presence of technicians and film equipment is a natural element. Additionally, in a performance attended by people through VR, the venue can be anywhere and the audience is almost limitless.
With microphones and headphones, the audience can cheer and applaud and hear those around them in the virtual venue cheering too, creating a very real atmosphere. It could transform live entertainment.
Hampton, Middlesex, UK
Dogged by doubt
I confess to being less than convinced by Pat Shipman’s explanation for the extinction of the Neanderthals (14 March, p 26).
She begins by describing the similarities between modern humans and Neanderthals, and the fact that we interbred, but her assertion that this was rare is not substantiated.
I would have thought that the modern genetic admixture of up to 5 per cent Neanderthal in those of non-African descent, which has survived in our gene pool without further input for tens of thousands of years, argues for more frequent encounters than rare ones.
Shipman goes on to propose that our ancestors developed their relationship with wolf-dogs in communities that coexisted alongside Neanderthals for thousands of years, and implies that the latter failed to observe, learn and mimic such activities. Shipman tells us that all known wolf-dogs occur in human sites, but the absence of evidence at Neanderthal sites is surely not evidence of absence.
She may be right in declaring that humans kept their dogs and the secret of their training strictly to themselves, but I find it hard to believe they managed to do this successfully for millennia.
Glasshouses, Harrogate, UK
Migraine methods
I enjoyed Helen Phillips’s recent article on the neurological changes in the brains of people who experience migraine (7 March, p 38).
About 35 years ago, when much less was known about the disorder, I attended a lecture in which an eminent US physician described the typical patient at his migraine clinic as a well-dressed woman, but did not mention any possible hormonal link with migraine attacks.
At the time, it was easy to infer a swipe at “uptight bored housewives”, but perhaps his observation unwittingly supports the more recent work? My friend who has migraines dresses neatly, and cannot tolerate untidiness or background noise from radio or conversation 鈥� all could be signs of the mental distress caused by progressive structural changes to the brain. Being a bit uptight may be the result rather than the cause of a tendency to have repeated migraines.
Tiverton, Devon, UK
Migraine methods
With a family history of migraineurs going back at least three generations, I was prone to motion sickness which was exacerbated by flickering lights, such as that caused by driving past tall trees. I suffered no headaches until I started using a contraceptive pill in the 1970s.
Frequent migraines occurred thereafter, even without the pill, until a ruptured ovarian cyst resulted in a hysterectomy in my mid-thirties. I haven’t had a migraine in the 30 years since. Drastic, but totally effective.
West Launceston, Tasmania, Australia
Taking a dim view
David Hambling mentions that the UK Royal Navy developed a laser system to blind attacking pilots in the 1980s (7 March, p 44).
In fact, it was a Ministry of Defence establishment that put an experimental laser on HMS Hermes during the Falklands war but it was never used. I learned recently that naval commander Sandy Woodward did not like the idea and banned its use. Who said chivalry is dead?
Stoke Gabriel, Devon, UK
Self-policing cars
Further to letters on self-driving cars (28 February, p 54), people only misbehave when they think they can get away with it, or if they don’t care about the consequences. Self-driving cars will have cameras recording everything around them. Anyone breaking rules to disrupt traffic flow will be easily identified. If the consequences include being prohibited from using the network, you would think hard before either disrupting traffic or mistreating the cars.
People underestimate how motivated governments are to make these vehicles work. They can see the huge benefits to their health and welfare budgets if they can significantly reduce the cost of road accidents. Every dollar wasted on patching up people is another dollar they can put towards productive projects that improve society.
Auckland, New Zealand
Prime directive
Further to earlier letters, there is another reason why aliens may not have visited us (7 March, p 53). Any aliens advanced enough to cross the galaxy are likely to have strict rules about contaminating new worlds with their presence, much like scientists here have when visiting undisturbed places.
To such an advanced race we would appear primitive and barbaric, and far too dangerous to be exposed to their technology. Perhaps when we have achieved world peace, eliminated poverty and tamed climate change we will be permitted to meet these aliens.
Abinger Hammer, Surrey, UK
Siege breaking
Victoria Esses’s article on immigration is a breath of fresh air in a stale and depressing debate (7 March, p 26). She is more qualified than I to estimate the importance of rationality in this zone, so it is encouraging to hear her optimism for the possibilities in nations built on immigration. Yet I still find it hard to be optimistic here in Australia, where our prime minister and leading advocate of the siege mentality Esses describes is himself an immigrant.
Cygnet, Tasmania, Australia
Future prices
Calculations of the carbon footprint left by our consumer purchases tend to be complicated by how deep one gets into the supply chain.
What would be the carbon footprint of driving my rare-earth filled electric vehicle (14 February, p 35) 30 kilometres to the nearest store selling LED-grown greens (p 30), and paying for it with bitcoin (31 January, p 35)?
Morgan Hill, California, US
Syrian explosion
The idea that global greenhouse emissions contributed to the Syrian civil war may be true,
but this is quite a minor factor (7 March, p 6). A more important factor is the quadrupling of the Syrian population since 1960. With a population explosion like this, the country was bound to reach a point where agriculture was insufficient and unemployment would rise, even without global warming.
Les Essarts-le-Roi, France
For the record
鈥� Colossus was used to crack Nazi Germany’s codes, but not Enigma (14 March, p 36), which was blown apart by the bombe machine at Bletchley Park.
鈥� While NASA’s probe Dawn is the first to orbit two different worlds (7 March, p 6), earlier spacecraft have visited multiple planets.