Letters archive

Laws on licensing and liability are important for self-driving cars (14 February, p 20) , but nowhere have I seen a discussion of the most crucial factor: will they be allowed to travel unoccupied? If they are, it will radically change the way we use our cars. Commuters will no longer pay for expensive town-centre …

With the news that driverless cars are coming to our roads, should we be discussing what will happen when the car has to choose between the safety of its occupants and the safety of other road users? Should it avoid hitting a pedestrian by steering into a river, for example? Tewkesbury, Gloucestershire, UK

Hal Hodson underestimates the difficulty that public opinion represents when it comes to self-driving cars. He assumes that if these vehicles can be shown to be safe, people will accept that they are. But that is not how people behave – the fall in vaccination rates reported elsewhere in the same issue is an example. …

Changes in human behaviour may make driverless cars unusable. Why would you wait to cross the road, or pull out at a junction, if you know that the approaching cars are programmed to give way? London, UK

In writing about the origins of the Up Helly Aa festival in Shetland, Dan Jones writes that "nobody knows quite where the name came from or what it means" (17 January, p 36) . It may just be that no one needed to ask, because with a touch of mutated spelling, a modern day Swede …

Manuel Eisner's fascinating article shows that many forms of violence are avoidable in our societies (7 February, p 26) . Two other factors are likely to contribute to reducing violent crime, which could be included in thinking and planning for future efforts to do so. First, no-fault divorce allows couples to separate in a civilised …

The plan to sell home data centres to customers as heat sources sounds innovative, but seems to be missing some key financial points (7 February, p 20) . Each customer will need to sell the extra computing power online. The cost of a high-bandwidth connection to the internet, and an intermediary to allocate the processing …

Hal Hodson writes that "using our computers generates plenty of waste heat. Time to harness it to warm our houses". Isn't warming my house what my desktop, home server, laptop and various other devices do already? Stocksfield, Northumberland, UK

Michael Berkson writes to bring attention to the patents filed by Arthur Pedrick, one of which proposes transporting fresh water from the polar ice caps to desert regions by means of snowballs drawn through a large pipe (31 January, p 55) . Your cartoonist illustrated this with a polar bear arriving in the Australian desert …

Andy Ridgway is right to draw attention to the supply of rare earth elements for use in smartphone electronics (14 February, p 35) . But the utility of these elements depends on a chemically-inert dopant carrier and heat transfer gas: helium. This element should also be included as a critical raw material. Helium has been …

There is a historical precedent in producing food in cities (14 February, p 30) . As the size of cities grew at the end of the 19th century, the time to transport milk into cities from the countryside also grew. With no refrigeration the milk frequently went sour before it reached customers. This led to …

The question of whether a truck becomes lighter if its cargo of birds takes flight was answered definitively in 1961 by some fellow graduate students at the Colorado School of Mines (24 January, p 13) . We captured a honeybee in a small glass jar with a tight-fitting lid and placed the assembly on a …

Your brief report gives the impression that launching satellites into orbit from an aircraft would be a novel approach (14 February, p 21) . This has in fact been routine for the last 24 years. The Pegasus launch vehicle built by Orbital Sciences Corporation is launched from an airliner at 12,000 metres. It has carried …

It is a nonsense to submit to the voodoo that says germ-line therapy is necessarily a bad thing (14 February, p 26) . Given the rate of progress in gene sequencing, it could soon be practical to combine pre-implantation genetic diagnosis with IVF. This would allow parents to choose the genes of their children by …

In view of some people's concern for the inaccuracy and emotive connotations of the term "three parent babies", how about "melange à trois" instead? London, UK

Hal Hodson reports on SAFFiR, a firefighting robot built for the US navy (14 February, p 22) . Inventor Meredith Thring also developed one in the 1960s, while at the University of Sheffield. This autonomous machine was intended as a nightwatchman in factories, following a pre-programmed route and investigating and dealing with any fires it …

Steven Miles claims that agnosticism is an untenable position (21 February, p 54) . As I understand it, agnosticism is not a "don't know" position, but the assertion that the existence of god is unprovable. This is a more scientific position than either atheism or theism can claim to be. Walsall, West Midlands, UK

So lilac and turquoise have been designated "basic colours", recognised universally among English speakers (7 February, p 16) . It's nice to have two new colours. On the other hand, I've never considered pink to be a fundamental colour. After all, it's just light red, really. Isn't it time that pink was downgraded to "dwarf …

I believe there is a reason behind time appearing to speed up as we age (31 January, p 54) . It is simply that the perceived duration of a defined period of time depends on the proportion of our life to date it would represent. I am now 91, so according to this idea each …