Letters archive

The world of quantum computing is complex, and while we appreciate Michael Brooks educating audiences on the various efforts, there were some misconceptions made about the D-Wave system in his article (18 October, p 43) . In particular, the article's table "Which quantum computer is right for you?" indicates that the D-Wave machine is only …

In support of harmonising regulations between the US and Europe through the Transatlantic Trade and Investment Partnership (TTIP), designed to break down barriers to trade, Tracey Brown asks who would defend a return to the wasteful delays of countries running separate clinical drug trials to meet local regulations. (1 November, p 33) I for one …

I thoroughly enjoyed reading Tracey Brown's thoughts on TTIP and regulatory cooperation. However, Brown says chemical regulators look at benefits and risks when making assessments. The European Chemicals Agency is bound to similar requirement as the European Food Safety Authority and can only consider risk. Brussels, Belgium

John Middleton cites examples of private companies that sued national governments for loss of profits under agreements similar to the Transatlantic Trade and Investment Partnership (TTIP) (1 November, p 34) . The question that occurred to me as I read about the various instances was of enforceability. If a legal complaint should prove to be …

It's a good question. Under existing trade agreements, arbitration procedures are enforced by the treaty itself and cases are heard and enforced by arbitration panels such as the World Bank's International Centre for Settlement of Investment Disputes. But nobody knows in the specific case of TTIP because negotiations are ongoing and conducted in private.

Imagining a world without fossil fuels, Michael Le Page fails to mention that without them, there is no way modern intensive agriculture could have developed (18 October, p 34) . Think of diesel for tractors, combines and distribution trucks, electricity for cold stores, and petroleum-derived agrochemicals. Without those things, we could not have huge modern …

Although we are blessed in New Zealand with an abundance of renewable resources, these are not enough for our country of just 4 million. I work at a large electricity company in New Zealand. Our energy portfolio is mostly hydroelectric and geothermal. But we also burn natural gas and the odd bit of coal. Almost …

You report that banded stilts tracked by GPS tags were found to fly 2200 kilometres in two days (1 November, p 18) . That's crazy. Did anyone sit down and calculate average velocities of these birds? Foxboro, Massachusetts, US

Katharine Sanderson sets out the wondrous potential of new 2D materials such as graphene (25 October, p 40) . Like all good things, however, there may be a downside overlooked in the excitement of discovery. A key property of graphene is its high strength and, presumably, durability. So what are the likely consequences of a …

Regarding the 2008 global market crash, the Queen may well have asked "why did nobody notice it?" (1 November, p 28) . But she was wrong, some people did. Many were laughed at and some quietly got ready for it. Gregory Zuckerman's book The Greatest Trade Ever gives a wonderful account of how John Paulson …

In your article on decoding brain signals (1 November, p 8) , the scientists report that they have followed their work on reading these impulses by "turning their hand to predicting what songs a person is listening to by playing lots of Pink Floyd to volunteers". Is this ethical? Hampton, Middlesex, UK

In Jacob Aron's article on hybrid computers, Chris Eliasmith says that neural networks are required "if you want to build a computer that is cognitive in the way we are" (1 November, p 21) . But do we? I'm with Elon Musk in thinking that fundamental questions like this need to be asked and the …

In her guide to the human mind, Caroline Williams recommends caffeine to shake off sleep inertia in the mornings (4 October, p 34) . This advice is worthless as any studies supporting her contention were inevitably carried out on caffeine addicts. I gave up caffeine 26 years ago and I am fully awake every morning …

It's easy to find out if e-cigarettes help you quit or get you hooked (1 November, p 35) . Just ask the tobacco companies if they are for or against them. Berlin, Germany

I was fascinated by Michael Slezak's article describing a new take on the many worlds theory for explaining quantum mechanics (8 November, p 6) , particularly as the theory predicts that as few as 41 other universes existing alongside ours could explain these effects. Is it possible that the answer to "Life, the Universe and …

The universe modelled by Howard Wiseman and his colleagues uses 41 worlds including ours. But that was the minimum number needed to get a qualitatively similar result to the double-slit experiment, so 42 would work too.

• Our claim about a burst water main near Singapore's Marina Bay Sands didn't hold water; the leak was several hundred metres away and was spotted before it could threaten the complex (8 November, p 20) .