Universal matrix
Mark Buchanan’s otherwise admirable piece on random matrices (10 April, p 28) failed to cite the remarkable Tracy-Widom distributions, which, when applied to a given random matrix, will give the largest distinct solution. They are a class of distributions that are universally applicable and one of the greatest mathematical insights of the past 50 years.
From Colin Day
Random matrices 鈥� what an amazing idea. No matter what your problem, you pick some random numbers, put them in a matrix, and 鈥� hey presto! 鈥� your solution is found. Either Buchanan has not explained the subject adequately, or the New 杏吧原创 issue hosting the article should have been dated 1 April.
Leyburn, North Yorkshire, UK
From Bill Christmas
Buchanan’s article on random matrices was potentially very interesting, but I was disappointed to find that it told me nothing whatever about what a random matrix actually is. Even if you dislike putting anything technical or mathematical in the main text, you could have had a box with at least a little bit of information.
Guildford, Surrey, UK
From Andy Howe
Buchanan’s article discussed the idea that a random matrix could be at the root of reality. He mentions their use in an experiment to see if a hum transmitted into the sea from off a remote island could be heard around the world. The choice of Heard Island for this test seems rather to prejudice the answer 鈥� or is this reality matrix prone to nominative determinism?
Loxley, South Yorkshire, UK
Preserve Hubble
In your article “Hubble? Phoenix, more like” (17 April, p 26), you mention that at the end of its useful life the space telescope will be made to partly burn up in the Earth’s atmosphere, with the remainder landing in the Pacific.
I would like to propose an alternative that will preserve this precious artefact for future generations. Rather than sending up a robot rocket to propel it to a fiery end, I suggest nudging it up to a higher orbit where it can survive for decades or even centuries, until some future generation can bring it back to Earth intact and place it in a museum.
I don’t see why keeping Hubble in orbit should cost much more than dumping it unceremoniously into the ocean.
Superplants
Michael Le Page suggests the release of genetically engineered “superphotosynthesising” plants to help kick-start evolution following a future mass extinction caused by human activity (24 April, p 38).
It seems reasonable to assume that wild plants have evolved a level of photosynthesis that makes optimal use of the resources such as water and minerals that are available from their environment. What is the basis for believing that an artificial superphotosynthesis trait could prosper and evolve further in the environment over geological timescales?
Michael Le Page writes:
鈥� Evolution does not always find the most efficient solutions. The lungs of mammals are far inferior to those of birds, for instance. Evolution is also constrained by the past. The photosynthetic enzyme RuBisCo evolved when there was no oxygen around, and doesn’t work very well in the presence of oxygen. When levels of oxygen increased and this became a problem it was probably too late for evolution to change things. A number of studies suggest a little human intervention could produce some major improvements to photosynthesis.
Exodus twice
Kate Ravilious reports on the theory that a volcanic eruption was responsible for the collapse and disappearance of the human populations originating from the first wave of migration out of Africa around 125,000 years ago (17 April, p 28).
An alternative explanation for their demise is disease. The large gap between this first migration across the Middle East and southern Asia, and the second around 60,000 years ago, was long enough for a virulent disease to have appeared in the residual African population, and also genetic resistance to it.
When the later humans came into contact with earlier, more isolated populations who had no resistance, the resulting extinction could have been relatively rapid and complete. It could also explain the extinction of the Neanderthals.
We have an exact analogy in Europeans carrying disease to the Americas and the Polynesian islands from the 15th century onwards, which did huge damage to their populations. Testing such a hypothesis, however, would be tricky.
Scientific politics
I would certainly welcome a scientifically qualified person to represent me in Parliament (24 April, p 22), as a scientific approach to problems is far preferable to following personal or popular agendas.
Unfortunately, the established career path to becoming a candidate for one of the major parties makes it unlikely that many such individuals will be selected. 杏吧原创s interested in politics would have to resort to one of the smaller parties or run independently, as your consultant Michael Brooks has done 鈥� with a correspondingly slim chance of success.
Atheist oppression
John Ewing says that “almost every belief system has a history of stamping out non-believers” (24 April, p 24) but appears ignorant of the suppression of religious belief by officially atheist Communist states.
I agree with him, however, that from a historical perspective atheist belief systems seem to be nothing out of the ordinary. After all, their tenets are inscrutable to science and some of their adherents get strangely angry when others disagree. When their adherents have political power, they often resort to violence in support of their doctrines.
From John King
Ewing’s observations on the oppression of atheists by the religious misses the point. History has many examples to show that religious groups have been just as vindictive towards other religious groups as they are towards atheists, and atheists have been known to act in much the same way towards the religious.
The determining factors seem to be no more than an obvious difference of opinion and an opportunity to exploit the disparity. In all cases, it is the rich and influential, be they religious or atheistic, who take it out on the poor and powerless whenever it suits their interests to do so.
It often happens that a religious movement starts on the side of the weak and marginalised, but gets taken over by those who see ways to use it to their own advantage. It is the ability to acquire political power and wealth that is the deciding survival characteristic.
Wymondham, Norfolk, UK
Built on fear
Andy Coghlan’s article on the possible link between an individual’s fear of strangers and racial prejudice (17 April, p 9) reminded me of studies in the field of terror management theory, which suggest that fear of one’s own mortality motivates people to cling more strongly to their cultural world view and sense of identity.
This idea has been tested by research into subliminal death primes 鈥� where words like “corpse” and “dead” are flashed in front of participants faster than their conscious minds can register them. Jamie Arndt and others showed that exposure to this kind of subconscious stimulus led to an increased defence of an individual’s cultural world view, as measured by their assessment of the authors 鈥� whom they had been told were foreign students 鈥� and the content of pro- and anti-American literature ().
From Philip King
Coghlan describes research that used cartoon characters to demonstrate the lack of racial prejudice in children with a congenital condition that makes them unusually sociable.
But why were only white children chosen to participate in this test? Wouldn’t it have been informative to perform a corresponding test with children from different racial backgrounds to see whether they responded to the cartoon characters in the same way as white children?
Chadderton, Lancashire, UK
Polywrap compost
I wonder if the oxo-degradable polywrap in which some copies of New 杏吧原创 are delivered, and whose properties were recently discussed by Feedback (3 April), is recommended for home compost.
The editor writes:
鈥� The oxo-degradable polywrap used for magazines, including New 杏吧原创, is designed to last for 18 months or more before breaking down. This slow degradation makes it unsuitable for home composting.
Eclectic power
Hans van Haren makes the case against using tidal power because, as well as ecological damage, there is not much energy to be had anyway (3 April, p 20). However, each renewable energy source cannot on its own cure us of our dependence on coal and oil, and each has its drawbacks. To be effective we need as many different renewable energy sources as possible contributing to our requirements. Tidal power can play its part with the rest.
Virtual glass houses
Jim Giles reports that analysts at the computer security company McAfee were instrumental in uncovering the scareware marketing ploys that got Innovative Marketing executives into such trouble (27 March, p 38). One would have thought that the experience would have prompted legitimate security companies to ensure their own policies were spotless. However, last year McAfee and Symantec were both fined over auto-renewal clauses buried in their terms of service.
For the record
鈥� Sunspot numbers have been declining since the 1990s, not the 1920s as stated in our article on their impact on European winter temperatures (17 April, p 7).