Chess test
With reference to Thomas Smith’s letter pondering the impact of jet lag on mental functioning (18 February, p 33), I first encountered problems on a 16-hour business flight to Japan in 1974.
I took an electronic chess game to pass the time. It had 10 levels of difficulty and I could usually compete up to level 8. About 2 hours into the flight, I decided to play, set up a game on level 2 and quickly lost. I tried again and lost again. I realised my mental capacity was impaired, which I put down to reduced oxygen levels in the cabin.
When I got to Japan, it took me more than two days to return to my normal standard. I have also noted that I do not fully remember books read or films watched during flights. I now try to arrive at my destination on a Friday so that I can have two rest days before work to restore brain function and memory.
Now I see people on long-haul flights working intensely on laptops, and wonder about the quality of what they produce.
Big bang theory
One possible explanation for the strange booming sounds explored by Kate Ravilious (18 February, p 47), which was not mentioned, is the collapse of marine sediments, although the mechanism involved is uncertain.
Given the quantity of sediment deposited by the river Ganges in the bay of Bengal, this may well account for such noises in that area – known as Barisal guns.
The occurrence of unexplained booms at great distances from large bodies of water has also been put down to the well-known meteorological phenomenon of anomalous propagation of sound in the atmosphere.
Mind games
You reported concerns about the potential use of advances in neuroscience by the military in “Mind wars of the future” (11 February, p 6). The story began: “Wars of the future may be decided through the manipulation of people’s minds.” When was a war fought without manipulating minds? Normal, sane, healthy people do not kill each other: they only do so when they have been brainwashed by propaganda to behave like psychopaths.
It added that technology or chemicals that interfere with thought processes carry “the threat of indiscriminate killing”. Have you not heard of the British and US bombing of Dresden in 1945, the US bombing of south-east Asia between 1960 and 1975, the destruction of Fallujah, Iraq, by British and US forces in 2004, the Israeli attack on Gaza in 2008-2009 or the Nato strikes on Libya in 2011? Has any war been fought in the past 50 years that did not involve indiscriminate killing?
From John McCallum
Talking about mind control in warfare reminded me of a cartoon by Australian Patrick Cook. It shows two lines of trenches. In the distance, enemy soldiers hold up a huge sign which says: “Your mother never really loved you”. In the foreground an anxious soldier turns to his companion and says: “So this is total war”.
Stanmore, New South Wales, Australia
Beats and discords
Ian Stewart made an entertaining dash through the history of physics on the basis of seven crucial equations (11 February, p 34). But one bit was confusing: introducing the wave equation, he refers to “beats” as a buzzing noise produced by waves whose frequencies are not in simple ratios. If two musical notes are not in a simple ratio, what you get is a discord, not buzzing.
Beats are created when two vibrations have almost the same frequency, so that one periodically adds to or reduces the output of the other. In sound waves that creates an oscillation in volume, with a frequency equal to the difference between the frequencies of the two tones.
Ian Stewart writes:
• In the description of beats, I was forced to simplify a bit. Although there is a musical distinction between beats and discords, the physics and mathematics are essentially the same. A discord is a nasty buzzing noise with a high frequency; a beat has a lower frequency. Both are caused by the ratios of the frequencies being combined not being simple fractions.
Other worlds
Further to calls to boost the Search for Extra Terrestrial Intelligence (SETI) which looks for artificial radio signals, so it can check exoplanets (11 February, p 28): it is reasonable to assume radio communication will eventually be superseded by a technically superior system.
If sentient alien species do exist, they are likely to be either far ahead of us technologically or just taming fire – not at exactly the same stage as us. The odds of detecting an artificial radio signal would be slim.
The editor writes:
• SETI’s Jill Tarter did describe a targeted search of appropriate exoplanets as a long shot.
Moral maze
You raised the moral puzzle of why most people would be prepared to redirect a runaway tram car onto a branch line where it would hit one person but avoid the five others it would have killed had it continued, but would not be prepared to push one person off a bridge to achieve the same objective (18 February, p 10).
The article doesn’t mention one reason – how could we justify pushing someone off the bridge when we could achieve the same end by jumping off ourselves?
The editor writes:
• The trolley problem is posed in such a way that jumping does not do any good. You are presumed to be of normal weight, and not heavy enough to stop the tram, but the person you could push is hefty enough to do the job.
Bird brains
The photographs of bird nests by Sharon Beals raise questions beyond the genes of their builders (11 February, p 26). Weaver birds of Africa build huge condominiums of grass under which our ancestors may have sheltered. Perhaps they watched, fascinated, as other birds built with mud that hardened as it dried.
Did we learn to sew and weave, construct grass and mud huts, thatch and make bricks, from observing industrious birds? Do we owe our textile and ceramics technologies to the descendants of the dinosaurs?
Been there
In his letter (11 February, p 33), Bob Donaghy suggests the last car of a nonstop, high-speed train “breaking off” to become a tram and reach its destination. This is a variation on the “slip carriages” used in the past in the UK. In the 1950s I often had to sit in the last coach, as this was de-linked from the train and stopped at my station by a guard.
Full circle
David Bowman makes a good case for introducing elephants to control invasive grass in Australia (11 February, p 29), but I presume more dung beetles would be needed to deal with the extra dung. Would additional species have to be introduced? How about some toads to control the beetles?
Limited hiatus
Jeff Dickens, responding to my letter about a hiatus in the quest for cosmological answers, missed the point (11 February, p 32). The science I question is to do with the massive expense of cosmology and probing for the secrets of the universe.
I did not advocate the removal of the point of science, but a particular point of it. There are more important things – cures for disease, hunger and poverty – than the pursuits of cosmology.
Sofa science
Reading the discussion of game transfer phenomena (24/31 December 2011, p 76), in which player responses in video games can spill into real life, I must mention what I call the Sky+ effect. (Sky+ is a service in the UK that allows you to instantly rewind live TV using a hard-disc-based personal video recorder.)
One day I saw out of the corner of my eye something move past the window, but I was not quick enough to see what it was. Without thinking, I picked up my Sky+ remote and tried to rewind time.
First flight
I am sure your claim that the first uncontrolled steam-powered flight was achieved by Simon Langley in 1896 (4 February, p 3) will be challenged by others, but it was surely predated by John Stringfellow of Chard, UK, who flew a steam-powered aircraft in a disused lace mill in 1848.
The editor writes:
• There are numerous claims, but was the first by a substantially-sized aircraft of that type.
Long way round
The figures in the sidebar to your article on fuel wasted searching for a parking space (4 February, p 19) imply that the Earth has expanded 1000-fold to a circumference of 40 million kilometres and that the average American car does 24,000 miles to the imperial gallon. Good news!
The editor writes:
• Sorry, we were out by a factor of 103
For the record
• In the story on how prions drive evolution in yeast (18 February, p 14), the mechanism described involves reading RNA in ribosomes, not DNA as stated in the text and the diagram.