The problem with science fiction is rarely the big ideas, but the story around them. By Light Alone has a fascinating concept in a genetic modification that allows human hair to photosynthesise, with the aim being to cure world hunger but leading instead to mass economic inequality.
It’s an idea that might have better served a series of interlinked short stories rather than a single narrative from different perspectives hastily tied together at the end, not least because the sections are wildly uneven in length and tone.
The largest problem with the novel is Roberts’ writing style. Too often, it reads like he’s trying to impress in an undergraduate creative writing class (“he strained to put his body through those ineffectual resistances against gravity’s hostile intent”).
And while the story is ostensibly set a century or so in the future, many of the developments, both scientific and cultural, seem far too advanced for the timeframe (city names becoming phonetic abbreviations, new lifeforms running wild, humans dividing into the emotionally absent super-wealthy minority and scrabbling “leaf-head” underclass). There are good ideas here, but By Light Alone struggles to find a compelling story with which to showcase them.