Meanwhile, Zoe is getting some extra physics help from Henry when she's supposed to be working. Carter walks in just as Henry's demonstrating a little gizmo that uses acoustic pressure waves to turn a penny into a puddle of melty goo. Seeing something shiny, Carter sticks his finger in the middle of the wave and is surprised that it really, really hurts. He's lucky his finger didn't turn into a puddle of melty goo. That was an epically stupid move by Carter. Henry and Zoe are too disgusted with Carter's stupidity to be very sympathetic. Henry says Zoe's trying to figure out the frequency to melt copper ore. Zoe says she's totally in over her head in this new physics class and is still clearly angry at her father for making her take it. Carter's also mad, because he's got to tell Hood that no one believes him. Henry says he knows how it feels to have to do something unpleasant, as he's on his way to run a "troubling errand."