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Since the effects of an illness are easily compounded by the psychosomatic pain of thinking it is worse than it actually is, there may be a reasonable explanation for finding that a placebo works even if you know you are taking it. Maybe just knowing a doctor thinks you are well enough to take a …

I enjoyed David Robson's advice to the reader who worried about being gullible. He is right to point out that we are generally unable to tell if someone is lying in casual conversation. The reader might also be reassured by research showing that even those whom we might expect to be better at this, like …

It was interesting to learn of a suspected archaeal host responsible for its primal symbiosis with an aerobic bacterium. The theory of endosymbiosis for eukaryotic cell origins, controversially proposed by Lynn Margulis in 1967, now has ample support with the detection of complex nucleic acids and protein synthesis within today's mitochondria and chloroplasts( 17 May, …

I would like to share my method for addressing the emotional states of anxiety and unhappiness. Make a list of what is worrying you in one column. Then think of possible solutions and put these in the second column. Then work on how to achieve these( 10 May, p 30 ). It is important to …

Your look at emotions and their impact on us was excellent. However, it is worth raising the issue of where, in my view, they come from. I believe we inherit them from our parents, and they from their parents; no one sat us down to explain how we will feel about any situation we find …

The image of Woodhead Reservoir in Derbyshire, UK, made me wonder about possible uses for all that newly exposed, dried-up sediment that has been slowly filling the reservoir and reducing its capacity. Much of this stuff is good-quality soil biomass that is free or mostly free of artificial fertiliser, herbicides and insecticides. I would be …

The energy applied by some of the world's great minds to understand quantum gravity is something to celebrate, but the lack of any real progress in over 100 years implies a gap in the thought process( 17 May, p 30 ). A tenet of quantum mechanics is that the wave function of a quantum particle …

The possibility of geologic hydrogen reserves in mountain ranges is very interesting. But Frank Zwaan saying that these or any other fossil hydrogen sources are "like a free green energy source" is naive at best. Drilling for hydrogen is neither renewable nor without substantial operational and environmental cost( 17 May, p 14 ). Fossil hydrogen …

Rowan Hooper's Future Chronicles instalment "Through their eyes" reminded me of the 1967 novel Night Walk by the Irish science fiction writer Bob Shaw. In this tale, the blind hero designs a device in the form of a pair of spectacles that transmit the signals in the optic nerves of nearby animals into his brain …

A solid Dyson sphere built around a star to capture all its power would be unstable, just like one made of many satellites. Even a rigid sphere with its star perfectly centred would experience gradual drift, necessitating occasional corrections, which might be visible as bursts of radiation. Without such correction, it would eventually intersect with …