Rewritten from scratch for the iPad, Atom in a Box HD is an aid for visualizing the Hydrogen atomic orbitals, the three-dimensional states that the electron occupies in Hydrogen, a prime and otherwise unwieldy example of Quantum Mechanics. It interactively shows, in an immersive environment, what the Hydrogen atom "looks" like. Unique among visualizations of Quantum Mechanics, it uses highly optimized code to perform 3D volumetric raytracing through the electron wavefunctions probability density and presents its results in real-time. It animates and mathematically describes all 2109 eigenstates up to the n=18 energy level. The app links to an online FAQ (see the Support link), and the atom rotates with the accelerometer and magnetometer. The bottom line is: Explore! The user are meant to explore all aspects of the atom, what it is and what it can do.