From Guy Cox, Sydney, Australia
There are two problems with arguments in favour of Dyson spheres, massive structures that advanced alien species might build to capture all of a star’s energy. First, long before a civilisation could build one, the issue of hydrogen fusion would have been solved and so abundant energy would be available. Second, if the aliens’ star system were anything like ours, putting a Dyson sphere in place would lead to the extinction of all higher life, including them – which doesn’t seem like a bright idea(Letters, 29 June)!
