From Bryn Glover, Kirkby Malzeard, North Yorkshire, UK
I was a little surprised that Claudia de Rham’s article on new ideas about gravity made no mention of dark energy (11 July, p30). It seemed to be the logical next step to wonder, if gravitons have mass, and thus have finite range, whether there is any need, in considering the expansion of the universe, to invoke dark energy at all.
