Letters archive

You report the hunt for possible black holes that predate the big bang, which could be evidence for repeated big bangs and a type of cyclical universe. Perhaps our own big bang is just one of many in a larger cosmos, but has been particularly successful in balancing inflation and gravitational collapse, expanding for so …

Thank you for the guide to the mysteries of the quantum realm( 8 April, p 36 ). The chef at my local garden centre restaurant and I often deliberate on such matters across the counter, and last week we were discussing the relationship between quantum uncertainty and the basis of free will. The next server …

Many thanks for the really clear guide to the quantum world. It was helpful to see all the key aspects and relationships together. Despite being a regular reader, some things were new to me, such as that gluons travel at the speed of light. The section on how forces work was also very useful. Plus, …

Thomas Hertog recalls his and Stephen Hawking's subtle explanation for why physical laws and parameters are "just right for life", positing that they initially varied randomly over time. There is, however, a simpler explanation: that physics varies randomly over space. To be sure, the variations must be gradual over enormous distances. But in a sufficiently …

A sustainable population without overconsumption has been advocated for decades, but with minimal effect. With significant pressure now exerted through the IPCC and environmentalists to change destructive lifestyles and industries, there is a chance that warnings may finally take effect. Tragically, it is likely that few people in high-income countries over 40, with set lifestyles …

I question the UK government pushing for us to ditch modern gas boilers to heat homes before the power system is truly green. The efficiency of my gas boiler is about 95 per cent, whereas if I use grid electricity to heat my home, the efficiency of a gas turbine to generate it is around …

I am unconvinced that biscuits and cakes made with a 2:1 ratio of sugar to fat are naturally "irresistible". For years, we have made cakes at home using half or less than half the sugar recommended by standard recipes. Other flavours aren't overpowered and the resulting taste is more complex and interesting. Shop-bought cakes now …

The claim that hand stencils in Gargas cave, France, show a sign language is very unlikely – there is a more plausible explanation( 18 March p 38 ). One of the illustrations includes the anatomically tricky gesture of an extended little finger and an extended adjacent ring finger, while the next two fingers are folded …

The jury is still out concerning the meaning of the ancient hand stencils with missing or stunted fingers found in caves. I would like to suggest a new interpretation. Previously, it has been shown that cave art is usually located in the most resonant parts of the cave. Could these stencils be an early form …