Letter
I can only conclude that Feedback is “directionally challenged”. The meaning of the inscription on the face of Peter Groves’s son’s watch is perfectly clear; if you stand 100 metres from the watch and splash water at it, normal timekeeping will continue.
Letter
By chance I bought a new watch yesterday. Jewellery shops in Sydney have helpful displays to explain the grades of water resistance: WR for ordinary water resistance, light spray, sweat, light rain, as encountered in normal daily use; W50 for swimming but not suitable for diving, snorkelling, surfing; W100 for all water sports except SCUBA diving; W200 or greater for SCUBA diving.
When watches with a rating of 50 or higher are serviced they are supposed to be pressure tested to ensure that they still meet the specification. Perhaps this is all somewhat irrelevant in UK, given the Brits’ congenital allergy to water.
For the record
鈥� Owing to an editorial oversight, an item found its way into Feedback on 17 July that should not have appeared in the column. We apologise to Astronomy magazine for stating quite wrongly that it printed an obviously inappropriate time in a diagram about the 8 June transit of Venus.
Wet watch wit
Water-resistant watches. Apologies for not being in any way witty with this reply, but I understood that “100-metre water resistant” meant that the watch could withstand a 100-metre static head of pressure (Feedback, 17 July).
Obviously, if you’re (say) swimming, the dynamic pressure is far greater than the metre or so nominal depth your wrist will reach, because of the movement of your arm 鈥� so this kind of watch is OK for a swimming pool but you wouldn’t put it on your SCUBA gear.
Immuno-computing
It seems reactive antigens and antibodies can be implanted into what is effectively a microchip, and there are “hundreds” of antigens and antibodies that have potential in this application (10 July, p 19).
Could you also beef up the capacity of computer chips by replacing the binary logic gate with something offering considerably more options than “yes” and “no”? Have I just claimed prior art for the “antigen logic gate”?
Download trojan.exe?
I was disappointed to find that Will Knight’s article on spyware missed a key point that could have been extremely helpful to your readers (26 June, p 24). While it did mention a couple of very effective tools for spyware removal, it made no mention of how to make your computer immune to much of the existing spyware 鈥� which you can do by using a browser other than the inept Internet Explorer.
Although this will not prevent spyware from being installed by downloaded applications such as Kazaa, it can stop it from interfering with browsing, and it does prevent spyware from being installed directly from web pages, which is a big problem for many.
Simply switching to another browser such as Opera or Mozilla would instantly eliminate much of the spyware threat. I myself recommend Mozilla Firefox, which can be found at . Prevention is better than a cure.
Eye spy
I read your article on myopia with great interest (10 July, p 12). I too am quite near-sighted, and since early childhood, have been an avid reader of any printed material I have come across. I have by now reached the stage where I am unable to visit our local restaurants without compulsively reading and spell-checking the menus.
Having applied the same diligence to reading your article, I would like to point out that the picture seems to show a child wearing glasses for far-sightedness, and not myopia. The lenses seem to enlarge the child’s face, and not make it appear smaller, as lenses to correct myopia do. Maybe the caption should not read “Too much reading?” but “Too little reading?”
Of course, you are in good company here: In William Golding’s novel Lord of the Flies, the stranded children use the lenses of a pair of glasses taken from a myopic child to light a fire, even though this type of lens should have the effect of diverging and not focusing the sunlight.
Off to polish my specs鈥�
Letter
With the wires Afhar has created a diffraction grating that will scatter the photons in precisely the way needed to recreate the original diffraction pattern but with the new (and unknown) paths for the photons to the detectors. Sorry, but the score is still Bohr 1, everyone else 0.
The editor writes:
鈥� We have had many more letters suggesting that, by placing the wires in his experiments, Afshar creates a diffraction grating. Afshar rebuts this suggestion. The wires are 1.3 millimetres apart, much more than would diffract the 650 nanometre light used in the experiment, and 200 times wider than this wavelength, he says. He also claims that, since they are placed in the dark bands of the interference pattern there is no light falling on them to be diffracted.
Setting a precedent
Peter Rowland argues that a process is more fundamental than its particles because we can only observe a process by observing the particles taking part in it (17 July, p 24). However observation itself is a process. Chickens and eggs come to mind.
Letter
These wires will act like a diffraction grating, so that a photon from one slit may be diffracted into the detection channel for the other slit. In short, if the wires are there, we do not know which slit the photon came through; while, if the wires are not there, we cannot detect the fringes. The conventional interpretation wins again.
Bohr isn't wrong yet
Shariar Afshar has certainly built an ingenious set-up (24 July, p 30). However, if his double-slit experiment performed as claimed, it would refute classical optics rather than standard quantum mechanics. His grid of fine wires constitutes a diffraction grating, which splits an incident beam into multiple beams at angular separations equal to the angular separation of his pinholes. The image formed of each pinhole is not a single spot, but a row of spots. When both pinholes are open, so that the interference pattern exists, the spots imaged from each pinhole are superposed. A photon detected at one of these spots may therefore have come through either pinhole or, as quantum mechanics demands, through both pinholes.
There is no “which-way” information, and Bohr’s ideas do not need to be thrown on the scrap-heap just yet. Afshar has not succeeded where Einstein failed.
Hard to stomach?
I am amused by the apparent revulsion over monkey tea (Feedback, 10 July). My wife is of Chinese extraction and confirms that monkeys are used to collect herbs from places inaccessible to humans. Monkeys are also used to harvest coconuts in many countries, and cormorants to catch fish in China. No doubt there are other examples of animals being used similarly elsewhere. People in the UK use collie dogs to herd sheep, ferrets to catch rabbits and so on.
Also, your note on weasel coffee should not be limited to Vietnam. Kopi musang used to be highly valued in Indonesia. A musang is a variety of civet cat. The coffee “bean” is protected by a skin so tough that it used to be referred to as a parchment, and the bean would pass through the civet cat’s intestines unaffected, to be washed out of the dung later, and the skin then removed. The musang only chose to eat perfect fruit, neither under nor overripe, and was thus deemed more expert at harvesting beans of the very highest quality than we humans are. I know it sounds revolting, and I have not knowingly drunk any as it is appropriately highly priced, reserved for the high and mighty and not available to yokels like me.
Letter
How can the scientific and business communities combat the widespread misuse of the term “renewable energy”?
The subject of Renewable Energy: Practicalities, the House of Lords report reviewed by Jenny Hogan and Philip Cohen, was in fact renewable electricity. This is a clear demonstration of the UK’s civil service using “renewable energy” to refer only to electricity from renewable resources.
But this is far from being the only or even the most significant form of renewable energy in global terms. It is time for renewable heat to be brought out of the shadows. It has been a poor relation for far too long: the UK should fall in line with the rest of northern Europe and start to realise the enormous potential for cuts in greenhouse gas emissions offered by heat pumps, heat from biofuels, solar thermal systems, and so on. Nor should we ignore the home and export market potential for wind pumps, wind-heat conversion, hydraulic rams, hydraulic air compressors鈥�
The phrase “renewable energy” must be extended to mean renewable energy 鈥� in all its manifestations.
Plane common sense
Tam Dalyell’s piece about the impact of air traffic on climate change addresses a vital issue that is often obscured by the debate about numbers (17 July, p 45). Our fundamental concern is that a policy permitting unhindered growth in airport capacity directly contradicts the UK government’s goal of reducing carbon dioxide emissions by 60 per cent by 2050.
The Treasury and the Department for Transport predict that aviation’s share of UK CO2 emissions could increase fourfold between now and 2030, while other sectors of the economy are working hard to cut back their emissions. All seem to agree that aviation would contribute about a quarter of the UK’s total contribution to global warming by that time. If we include all the emissions from air travel, unchecked expansion in this sector could lead to aviation accounting for over half of the UK’s global warming budget by 2050.
The soaring growth of aviation emissions is clearly both unacceptable and unsustainable. We agree that international action to include aviation in emissions trading schemes is both welcome and necessary, noting that these schemes must recognise the unique aspect of aviation: CO2 emissions only account for about a third of the global warming caused by aircraft.
However, progress in the domestic arena is needed without delay. The government should encourage a shift to more environmentally-benign modes of transport such as rail, support technological innovation and impose charges to reflect the damaging nature of short-haul flights.
Do the same with less
What a curiously narrow approach you are taking to the optimum way to match the UK government’s sustainable energy targets (17 July, p 6). There really is a lot more to this debate than the simplistic wind versus nuclear power equation. Energy policy is not just about supply: it is every bit as much about demand.
If you examine the government’s official energy strategy up to 2020, at least half of the CO2 savings must come from doing what we now do, but doing it better.
Driving cars that guzzle less gas; running appliances that are less wasteful; occupying buildings that are better insulated: the technology is there to provide us with light, heat, and motive power by burning a tiny proportion of the fuel we currently use.
I realise that none of this is quite so excitingly controversial as the little debate you posit. But in truth it is really where the main policy wheels are turning. I’m sorry you haven’t appreciated that yet.