Apparently, we’re in the middle of a “global infidelity crisis,” a crisis that can only be solved by a smart mattress that pings your phone when it’s being used for sex. Wait, what? Smarttress is a real-looking product from Spanish company Durmet, which claims to use ultrasonic sensors to detect when two people are going at it on a bed. It then pings your phone to inform you of this fact. I’m still partly convinced that this is a late April Fool’s, but working on the terrifying assumption that it’s not, let’s look at this idea on its merits. On...