A decades-old mathematical riddle that claims to calculate humanity's expiry date is back in circulation, and it has people arguing online about something nobody can actually prove: how much time our species has left. The trigger is a report by The Metro, which put the spotlight back on the "doomsday argument," a decades-old theory that uses probability, not prophecy, to guess at how close humanity might be to its final chapter. The report has pulled a niche academic debate straight into mainstream conversation, and the internet is, predictably, divided.
