Matthew Moynihan is nothing if not a realist. He knows that the technology he champions suffers from what public relations people call reputational issues. And that’s because for several decades nuclear fusion has at best been saddled with the qualifying term ‘tomorrow’s’, while at worst, it’s a fringe distraction often written about in green ink and block capitals.

Even Moynihan’s co-author on ‘Fusion’s Promise’ had his doubts. Alfred B Bortz in his early meetings with Moynihan wondered: “Aren’t fusioneers chasing steadily moving goalposts?” In the preface to their book – wonderfully subtitled ‘How Technology Breakthroughs in Nuclear Fusion Can Conquer Climate Change on Earth (And Carry Humans to Mars, Too)’ – we’re told that Moynihan answered Bortz’s question in the negative, insisting that the technology was within reach. In fact, “fusion is already finding commercial application in other economic sectors”.

While coming from different generations and...