In The Truth Machine, a science-fiction novel published in 1996, scientists invent a device that can detect lies with perfect accuracy. It abolishes crime, changes the world, and generally saves humanity from self-destruction. Which is nice.

Could such a machine ever be a reality? Not if our current technology is anything to go by. The polygraph has been around for almost a century, with wired-up offenders and twitching needles becoming a staple of criminal investigations. But there is no solid evidence that the signs it looks for – faster heart rates, shallower breaths and moist skin – can accurately indicate whether someone is telling a lie. Underpinned by fluffy theory and backed by a weak and stagnant evidence