The original version of this story appeared in Quanta Magazine. In 2020, scientists detected a gas called phosphine in the atmosphere of an Earth-sized rocky planet. Knowing of no way that phosphine could be produced except through biological processes, “the scientists assert that something now alive is the only explanation …

The original version of this story appeared in Quanta Magazine. Luca Giomi still remembers the time when, as a young graduate student, he watched two videos of droplets streaming from an inkjet printer. The videos were practically identical—except one wasn’t a video at all. It was a simulation. “I was …