In which we talk about the fastest spectroscopy yet, attosecond spectroscopy, which can resolve electrons moving around atoms. The topic begins with Christian Spielmann in 1997, working to get shorter and shorter laser pulses, and continues with Ferenc Krausz. We discuss what you might be able to inspect using these short light pulses, such as how the shape of atomic orbitals oscillates after ionization, how you can change the opacity of a substance for a brief moment, and fluctuations of wat...