17 December 2011 | NewScientist | 31

our skin during the winter months, could this contribute to making us seasonally depressed?London, UK

The editor writes:n The researchers say there is no evidence that rhodopsin expression in skin can be linked to any kind of depression, so perhaps best to wrap up warm instead.

Net gain From William Hughes-GamesSo the fish stocks in the Canadian Grand Banks are finally recovering (30 July, p 5). A smart fisheries department would now put half the area out of bounds, permanently.

Imagine getting the fish stocks back, not to what they were in 1930, but to what they were when the Portuguese first arrived in the area. Fishing would be so good that there would be no need for bottom trawls or drift nets. Simple hook and line would yield fantastic catches, and there probably would not be any need for quotas. One regulation would suffice: sink any boat found fishing in the no-go area.Waipara, New Zealand

Man strokes fishFrom Dan LufkinYour report that fish find massage soothing comes as no surprise to scuba divers (19 November, p 7). Several species seem to find divers interesting, and will often hang

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For the recordn In the feature “Friend or foe?” (3 December, p 46), the salt content of a small pot of yogurt should have been given as 0.4 grams.n The story on the discovery of exoplanet Kepler-22b (10 December, p 4) should have said that if it is at the lighter end of the possible mass range for a planet 2.4 times as wide as Earth, it might be gassy like Neptune, and if at the heavier end, it might be rocky.

around to be scratched and patted. Groupers, in particular, like to have their bellies rubbed.

Recently, diving off Little Cayman, I met a grouper about 10 metres down which swam below me for 20 minutes. I could put my hands around it and squeeze. The fish would shimmy out ahead, then come back into position for another treatment. Personally, I could no more eat a grouper than I could a cocker spaniel.Frederick, Maryland, US

Doubly infinite?From Hillary ShawSo our universe is one of 10500 universes in a multiverse (26 November, p 42). But what lies beyond the multiverse? Is it just one of 10500 multiverses in a polyverse? Maybe it’s a reversal of the idea from mathematician Augustus De Morgan’s poem: “Great fleas have little fleas upon their backs to bite ‘em, And little fleas have lesser fleas, and so ad infinitum.”Newport, Shropshire, UK

The editor writes:n The suggestion is that the multiverse is everything.

From Brian HortonThose who are convinced that the multiverse explains everything should read The Infinity Puzzle by Frank Close, which Amanda Gefter reviewed (29 October, p 54) and which describes how quantum field theory appeared to require electrons with infinite mass and charge. The infinities disappeared with further development of these theories. No doubt the infinite number of universes will also disappear with a little more thought.West Launceston, Tasmania, Australia

From Phil CarterIf the multiverse contains all possible versions of reality, could

we not be living in one of the universes where the inhabitants are destined never quite to make sense of physics?Lichfield, Staffordshire, UK

God of many thingsFrom Micky StarYour article about the workings of the human mind being more akin to quantum, rather than logical, computation echoes the juxtaposition of eastern and western schools of thought (3 September, p 34).

The ways of the west have their roots in rigid, solid, geometric forms, medieval scholars seeing these harmonic principles as the divine path to God.

The ways of the east could be seen as possessing a quantum element. For example, in Hinduism, the god Brahman was a multifaceted being whose existence simultaneously spanned multiple geo-temporal locations, a feat that quantum science is no stranger to.London, UK

Nothing’s upFrom Tissa PereraI thought physicists had given up hope when I read “Why nothing matters” in the online version of the editorial to your special issue covering zero, the empty set, electron hole theory, the vacuum and noble gases (newscientist.com/article/mg21228391.300).

It soon became clear though. What physicists need to do is to work on a TON – a Theory Of Nothing.Lewisville, Texas, US

Golden stickFrom Hugh ColvinSo ravens pick up sticks in their beaks and wave them about to attract a partner, and develop complex individual

vocalisations, behaviours that could be deliberate and intelligent, or simply down to hormonal triggers (3 December, p 16).

I pick up my gold-plated saxophone, stick it in my mouth and wave it about, which is how I met my partner. I, too, have developed a complex set of quasi-vocalisations: the sax approximates more closely to the modulations and overtones in the human voice than any other instrument.

“Are the ravens doing the same as us?” is as unanswerable as “Are we doing the same as the ravens?”Knighton, Powys, UK

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