32 | NewScientist | 18 February 2012

Fracking fearsFrom Derek BoltonWhile I appreciate that Peter Aldhous’s article was primarily concerned with the immediate health questions raised by the process of fracking, or cracking rock to extract natural gas from shale beds (28 January, p 8), its effects on climate change cannot be ignored since that, too, is likely to be bad for our health.

As some of the incentives for fracking come from the lower carbon emissions produced by gas-fired power stations, a key question is whether the extraction of shale gas has an additional impact on greenhouse gas (GHG) emissions. This is something recent studies say should be taken into account given the methane leakage such extraction creates.

Over 20 years, atmospheric methane has seven times the GHG potency of carbon dioxide, so leaks could easily wipe out the benefits of burning gas over other fossil fuels.

That is the conclusion of two studies carried out by Cornell University in Ithaca, New York, one published in Climatic Change in 2011 (DOI: 10.1007/s10584-011-0061-5) and one in press.

Reducing methane emissions may be an essential step to avoid climatic disaster, regardless of success in cutting carbon dioxide.Sydney, Australia

The editor writes:n A feature on this and other facets of gas production and use will be in New Scientist next week (25 February).

From Philip Mitchell, Blackpool and Fylde Green PartyScientists should not encourage fracking for shale gas in the UK (28 January, p 10), but instead press for a moratorium.

The threat is widespread. The main shale formations in the UK that could be exploited in this way cover half of England, with more offshore. Here in north-west England, where waste fracking fluid is being stored, some

residents have already reported respiratory problems. In addition, being woken by earthquakes associated with fracking has caused psychological stress.

We expect passenger cars to be proved safe before they come to the market; the same should apply to energy policy.Blackpool, Lancashire, UK

Science of sleepFrom Nich WoolfHaving been on call or rotating shifts for almost 40 years, I was interested in your Instant Expert on sleep, particularly the section on sleep cycles, to see how my coping mechanisms match current thinking (4 February).

I learned a long time ago that if you cannot have a whole night’s sleep, then having more than an hour but less than two will allow you to wake without feeling too drowsy. This fitted with your diagram showing all the phases of one sleep cycle occur in 1.5 hours.

Although waking from deep sleep, functions such as balance seem much better than if you wake part way through a cycle.Burnham-on-Sea, Somerset, UK

3D protectionFrom Eric BillettYou report that file-sharing site The Pirate Bay has started to offer “physibles” – digital objects that can be realised on 3D printers (4 February, p 22). The article says that while copyright and patents can protect music and inventions, there is very little protection for solid objects.

This is not the case in the UK, where “design right” and “registered designs” are used to protect intellectual property (IP) in the case of 3D objects. Design right is roughly the equivalent of copyright and automatically covers 3D designs, whereas a registered design offers more formal protection

to specific designs.It is true that these IP rights are

fairly new and not as well tested in the courts as copyright and patents, but they do form the basis of the future protection of 3D designs.Chellaston, Derby, UK

Holy rights?From Annette ThompsonI read with interest the interview with Isak Gerson, leader of the world’s newest religion “Kopimism”, which believes the

act of copying information is holy, (14 January, p 25).

Does this mean students can now plagiarise others in their essays under the protection of their religious belief?Newport Beach, California, US

Predator vs alienFrom Patrick WilsonI find it disturbing that a scientist would suggest introducing elephants to Australia to eat fire-prone, invasive African grasses (11 February, p 29).

Elephants are a disruptive force in any ecosystem they inhabit, and the numbers required for any real impact on invasive grasses would be huge.

Getting such a project up and running would take a long time and be very expensive. There are 12,000 elephants in Kruger national park in South Africa, which covers only 19,500 square

Enigma Number 1685

OPINION LETTERS

WIN £15 will be awarded to the sender of the first correct answer opened on Wednesday 21 March. The Editor’s decision is final. Please send entries to Enigma 1685, New Scientist, Lacon House, 84 Theobald’s Road, London WC1X 8NS, or to enigma@newscientist.com (please include your postal address). Answer to 1677 The answer and winner will be announced next week

GWYN OWENMy whimsical uncle tells me that he goes to his study at a certain time every day, but doesn’t say when. On Sundays when he arrives, he winds each of his two eight-day clocks and sets them to the correct time. One of the clocks gains an exact number of minutes each day, and the other loses the same, so the mean of the times is correct through the week.

He also tells me that on three days during a previous week (Sundays being excluded), as he

entered the study he jotted down the time from one or other of the clocks, and he now produces the resulting slips of paper with the times 8:56, 9:11 and 9:20 written on them. These times are not necessarily in the order in which they were written down, nor do we know which clock is associated with which timing. Nevertheless, my uncle tells me I can deduce that he noted the time on a particular day of the week.

Which day was that?

A noted eccentric

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