Editor's pick: The steep learning curve of rocketry
Jeff Hecht says space is still hard (18 July, p 24). Indeed. The engines currently used to launch rockets work on the same basic principles as the V2 rockets of 1944. In the 1960s, these principles were refined into the mighty F1 engines that powered the Saturn V rockets, followed by the more efficient and powerful Russian-designed NK33 engines.
These use what is called a closed cycle, in which . No one has yet built a more successful closed cycle engine, due in part to the failure of any American company to replicate the highly complex metallurgy necessary. Kuznetzov in Russia is very unlikely to restart production, even given a NASA contract.
The issue with all these engines is that they operate at the extreme limits of the capabilities of the materials available. And we just aren’t building enough of them to enable the designs to be worked upon. It took over 100 years and the building of millions of machines to refine the modern piston engine, which has at least 10 times the power and longevity of those from the turn of the last century.
Droitwich, Worcestershire, UK
Imagine there's no religion…
Joshua Howgego asks “What if… we find God?” (8 August, p 28). This ignores a much more plausible question: “What if… we all decide that God does not exist?”. Non-belief, or at least indifference to religion, is already the default position in Japan and Western Europe. In the US it’s the fastest-growing religious view.
If non-belief becomes the dominant view, we can expect religions to lose their political privileges in, for instance, public ceremonies and the UK’s House of Lords. Religious belief will come to be seen as a species of intellectual error due to innate features of human thought such as our preference for living agents as the causes of events.
Once we cease to take seriously beliefs that defy logic, we will be much more able to criticise all forms of irrationalism: commercial, political and scientific as well as religious. This will not solve all our problems: nothing will. But it will remove an important barrier to such solutions.
London, UK
Imagine there's no religion…
鈥� Those wishing to explore more ramifications of a godless future can read our recent feature on this topic (3 May 2014, p 30).
Imagine there's no religion…
I found the tone of Joshua Howgego’s piece a little odd. I am a non-believer for the reason that I have never seen evidence to support any sort of belief in any sort of supernatural entity.
However, if someone were to produce incontrovertible, reproducible evidence for the existence of God, then I would hope to be true to scientific method and unemotionally accept that evidence as reality.
The position of “anti-theists”, and that of those who dismiss such proof as “impossible” seems to me to be as irrational as that of current theists.
Kirkby Malzeard, North Yorkshire, UK
<b>First class post</b>
It’s absolutely not a quantum computer by any definition outside D-Wave’s own sales literature
Richard Marshall by D-Wave’s claims of qubit-crunching power (29 August, p 6)
Disembodied brain escape committee
Anil Ananthaswamy asks “What if… we don’t need bodies?” (8 August, p 28). If my mind could be accurately simulated on a computer, my simulated self would be very annoyed if its ability to do arithmetic calculations were restricted to what my “old” biological brain would do, when there was a powerful and accurate calculating machine on the same circuit board. In fact my simulated brain, if not given direct access, would be busy trying to hack its way out of the simulation.
What simulated mind would want to be merely an accurate electronic model of its human source when it could be an intellectual giant with the enormous power and capabilities of a conjoined system?
Tring, Hertfordshire, UK
So you want to tell us about free will
You ask what would happen if we discovered we had no free will (8 August, p 28). Free will is an idea so bad it’s not even wrong.
People, just like everything else, behave the way they do because of cause and effect and thus are deterministic, or they don’t behave because of cause and effect and thus are random.
Tell me what the term “free will” means and I’ll tell you what would result if we find out that humans don’t have it.
Fort Lauderdale, Florida, US
A gene can do more than one thing
Michael Le Page writes that gene editing can make cattle hornless “without affecting any of their other traits” (15 August, p 10). Can we be sure of this?
In humans, a single gene is implicated in the illness thalassemia, so it might be considered desirable to edit it out. But the same gene also 鈥� a potentially valuable trait.
St Andrews, Fife, UK
What makes a planet 'Earth-like'?
Yet again, excited astronomers and journalists are jumping up and down over finding “another Earth” (1 August, p 4). But Kepler-452b is not an Earth-like planet.
The Earth is part of a binary planet system, with the moon. The effects of being a binary planet have been suggested as major reasons behind the development of life.
Brentwood, Essex, UK
Jobs, not bogus training drivel
Lynne Friedli and Robert Stearn condemn the meaningless and inappropriate activities that unemployed people are forced to take part in, such as “building paper-clip towers” (18 July, p 24).
The same sort of bogus drivel has been padding the staff-training schedules of countless companies for years, and I suspect that managers are at long last expressing doubts about the excessively diaphanous nature of the emperor’s wardrobe.
But the purveyors of this “training” have apparently managed to reinvent themselves as the sure-fire answer to uncomfortable unemployment figures. About the only unemployment problem this is likely to solve is their own.
Riverstone, New South Wales, Australia
Neural network transparency
Tamara Quinn suggests devising a way to monitor how neural networks arrive at their answers (Letters, 8 August). It is an interesting point and if a network could itself provide a case-by-case explanation that would be useful.
I worked on neural networks at British Telecom research labs in the 1990s, and one possibility could be to modify the system in order to gather evidence from the points of greatest “neural” activity. That information could then feed into a symbolic post-processing stage, for error detection and correction, and to package such data into verbal statements that would justify each classification.
Horsham, West Sussex, UK
Sundial is more backward than that
You write that sundials are aligned north (8 August, p 13). This is true in the northern hemisphere.
Readers in the southern hemisphere 鈥� where sundials are aligned south 鈥� may take umbrage at this hemispherism.
Edinburgh, UK
The sovereignty of the beasts
William Travers, in advocating an end to the wildlife trophy hunting industry, continues the tradition of overbearing Westerners forcing their religions and morals on the people of Africa (8 August, p 22).
I am embarrassed that the Australian government has the same attitude regarding lions. This year it on trade in lion trophies 鈥� a position at odds with that of the Convention on International Trade in Endangered Species.
We should respect the governments of African nations as the rightful managers of their wildlife. And we should support, rather than undermine, CITES, the treaty that for decades has effectively regulated world trade in wildlife according to objective ecological principles.
Evatt, ACT, Australia
Meet Superficial Intelligence
Martin Rees says that biological brains will eventually be superceded by superior machine intelligences (1 August, p 22). His remarks follows recent comments by Stephen Hawking and others, calling attention to the supposed dangers of runaway artificial intelligence.
These assertions all surprise me. The machine intelligence we currently see is more superficial than artificial. How do Hawking and Rees think these automated sorters and calculators will reach such lofty goals?
London, UK
How to hack aircraft after all
Iain McDonald reassures us that the flight crew can take over if an aircraft’s computers fail or are hacked, and fly the plane manually (Letters, 8 August).
This would be fine at 30,000 feet, but what if the electronic attack took place at 300 feet during take-off or landing? Would the crew realise what had happened in time, and be able to take over and bring the plane under control before disaster struck? I very much doubt it.
Winchester, Hampshire, UK
<b>For the record</b>
鈥� And breathe. We meant to refer to Astrobiology, vol 15, p 119 () when discussing ways that oxygen might appear on lifeless worlds (15 August, p 8).
鈥� We reported tests for biomarkers of suicidality (22 August, p 10). These were tested by monitoring 265 men with psychiatric conditions, in two groups. One test involved trying to predict which of 108 men would develop suicidal feelings, the other looked at which of 157 would be hospitalised by an attempt.