30 | NewScientist | 12 May 2012

Overly optimisticFrom Elizabeth YoungE. O. Wilson picks up on our urge to group (21 April, p 34), which  is leaving us with innumerable paradoxical, overlapping loyalties. Kinships and religions, the ones that he recognises,  are only two: think local, think country, think race, think culture, think football team, think enemies and rivals.

But Wilson is surely engaging in a narrow form of optimism when he says a better understanding of biology is the key to resolving conflict. His solution, though useful, will not be enough to save humanity, let alone our world.London, UK

Born to dieFrom Graham ThomasFurther to Geoffrey Shephard’s letter suggesting stem-cell research could enable lifespans  of centuries through the manufacture of replacement  body parts (21 April, p 37). I cannot think of a better recipe for the intellectual and cultural stagnation of our species.

Death, as Steve Jobs observed, “is very likely the single best invention of life. It clears out  the old to make way for the  new”. Besides, how would  such long lives be financed,  or would we all have to work  to age 300?

A more valid objective would  be to make the last quarter of people’s lives healthier and more comfortable. A shining earlier example of such a philosophy is John Charnley’s replacement hip, which has restored mobility to millions in later life.St Albans, Hertfordshire, UK

Snuff saidFrom Byron RigbyIn CultureLab’s look at Immortality (7 April, p 47), both reviewer S. Jay Olshansky and author Stephen Cave appear to consider that the unit of survival is the individual. The battle against death is then the fight  for individual survival, whether through health measures, life after death, immortality of the soul, or legacy.

What if the unit of survival is the community, or the species? 

We have already seen the resurrection of the concept of group selection, after all.

Many of us are happy to  grow, spread our genetic and cognitive seed, then drop off  the branch. We might not even need to leave a recognisable legacy, so long as we make a difference during our time.Bundoora, Victoria, Australia

Hard problemFrom Martin BakerAs a physicist, I’m intrigued  by Christof Koch’s article on consciousness (14 April, p 24). 

His description of an  approach to a generic theory  of consciousness that involves linking physical neuronal firing patterns in the brain to an abstract, multidimensional space is strongly reminiscent of the phase space model of statistical physics. Physicists have honed  the phase space model into a powerful mathematical probe  of complex systems, out of  which emerges the profoundly important link between information and entropy.

In the past, researchers  from other disciplines brave enough to paddle in biological waters have labelled the development of a successful theory of consciousness as “the hard problem”. Physicists may perhaps be encouraged that a solution is now being sought on territory familiar to them, and they may find the link between 

consciousness, information and entropy particularly appealing.Eskbank, Midlothian, UK

Moon economicsFrom Ian ChappleI couldn’t help feeling that  mining minerals on Earth’s  mini-moons would not be viable (21 April, p 48). If a 2-kilometre-wide asteroid is worth $25 trillion ($25 × 1012), surely a mini-moon one-thousandth of the diameter of such an asteroid (and therefore one-billionth of the volume) would only be worth $25,000 ($25 × 1012 × 10-9).

There does not appear to be  any way in which the value of the minerals found on such a small moon could possibly justify the expense of getting there and bringing it back. Or am I missing something important?Rijswijk, The Netherlands

Power talkFrom Chris Goulden, Joseph Rowntree FoundationMichael Bond’s article on wealth and the research of Dacher Keltner and Michael Kraus throw up some interesting hypotheses regarding the impact of class, status and money on the way we interact with each other (21 April, p 52).

Teasing apart those three concepts is often hard and there are a host of assumptions made about the terms. This is one reason why the Joseph Rowntree Foundation has embarked on 

Enigma Number 1697

OPINION LETTERS

WIN £15 will be awarded to the sender of the first correct answer opened on Wednesday 13 June. The Editor’s decision is final. Please send entries to Enigma 1697, New Scientist, Lacon House, 84 Theobald’s Road, London WC1X 8NS, or to enigma@newscientist.com (please include your postal address). Answer to 1691 Factory parts: ENIGMA is 921375 The winner John Kelly of Walsall, West Midlands, UK

IAN KAYI have before me a number, which when written in binary is palindromic and has n digits. If I told you the value of n, and you wrote a list of all the possible palindromic binary numbers of length n, your list would have n numbers in it.

If your list was in ascending numeric order, and I told you the difference between my number and the next higher number in the list, you would be able to identify my number.

What is my number, in decimal form?

Binary palindrome

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