Â鶹´«Ã½

With reference to the interesting article by Ciarán Gilligan-Lee on quantum cause and effect, I would point out something that I have often noted, but that is always overlooked ( 29 November, p 36 ). History can be understood in quantum terms. The future is nothing but a series of probabilities, the present is where …

Jonathan R. Goodman argues that the selfish gene view of evolution is correct and bemoans the "old and tired" debate on whether niceness and group selection trump that. It is this binary thinking that is old and tired. Evidence for each view exists and must be synthesised into a 360-degree view. Competition and cooperation are …

Richard Black asks if a hearing aid can be designed with software to selectively amplify sounds coming from the direction you are facing. I can tell him that my hearing aid does exactly that ( Letters, 22 November ). Instead of picking up all the sounds entering the ear and amplifying select frequencies, my hearing …

David Flint says biomass carbon capture would require too much land area. He favours using chemical plants to capture carbon dioxide from the air. I would like to point out that, every year, about 440 gigatonnes of carbon dioxide enter the atmosphere from rotting vegetation, whereas we have about 1100 gigatonnes more carbon dioxide in …

As a contributor to the documentary Blue Planet Red , I would like to address the criticism in Simon Ings's review that xenon-129's presence in the Martian atmosphere implies ancient nuclear conflict only if you ignore the well-understood process by which a now-extinct isotope, iodine-129, would have decayed to xenon-129 in Mars's rapidly cooling lithosphere …

You report that a study by Satoshi Kojima and his colleagues may have solved the mystery of why birds sing at dawn, suggesting singing is suppressed by darkness, leading to a build-up of motivation that is released when the dawn breaks. This may explain the mechanism that mediates the diurnal pattern of singing, but it …

Regarding the feature Songs from the caves, the Lascaux cave paintings in France include a star map of the Taurus region of the sky with a bull painted around the Hyades, just as the constellation is depicted today ( 22 November, p 34 ). Dated at 17,000 years old, surely this is the oldest provable …

On the discussion of knowing when to give up on your goals, I contend that longing for perfection of oneself is an exercise in futility and frustration. Why? Because none of us is perfect and, despite our best efforts, alas, none of us will ever be perfect. Let's all relax a little and not set …

The Torino scale assigns asteroids a score of 0 to 10 based on their size, energy and probability of hitting Earth ( 15 November, p 38 ).