Hydrogen atom (non relativistic) hydrogen atom was solved for the first time within Feynman's path integral formulation of quantum mechanics. This work greatly extended the range of applicability of Feynman's method. Hydrogen atom A hydrogen atom is an atom of the chemical element hydrogen. The electrically neutral atom contains a single positively charged proton and a single negatively charged electron bound to the nucleus by the Coulomb force. Atomic hydrogen constitutes about 75% of the baryonic mass of the universe. In everyday life on Earth, isolated hydrogen atoms (called "atomic hydrogen") are extremely rare. Instead, hydrogen tends to combine with other atoms
Captain Atom of alternate Captains Atom, including Earth-13's Brigadier, the Captain Atom as depicted in the graphic novel "Kingdom Come" (Earth-22), and a Captain in a red/silver variant of the Monarch's costume, one similar to the Charlton Comics Atom (Earth-4), and a Hulked out variant named Attum from an unknown Earth. Several more variants are shown in "Countdown: Arena" #4, including a President Atom, a robot called Quantum Mechanix, Kid Quantum of the Legion of Super-Heroes, Captain Adamma, Quantum Boy, an anthropomorphic wolf version, a from Earth-30, a Doctor Manhattan-lookalike, an energy based-Atom who makes calculations during his attacks, and a giant-sized