Exotic atom to weak, electromagnetic and gravitational forces, muonic atoms are governed to very high precision by the electromagnetic interaction. Since a muon is more massive than an electron, the Bohr orbits are closer to the nucleus in a muonic atom than in an ordinary atom, and corrections due to quantum electrodynamics are more important. Study of muonic atoms' energy levels as well as transition rates from excited states to the ground state therefore provide experimental tests of quantum electrodynamics. Muon-catalyzed fusion is a technical application of muonic atoms. A "hadronic atom" is an atom in which one or more of the
Captain Atom not mentioned in the panel in which they appear, but the Captain Atom is visually similar to Charlton's original version of the character. However, according to comments by Grant Morrison, this alternate universe is not the pre-Crisis Earth-4. 2007's "" features Captains Atom from alternate universes. The combatants of the series are introduced as a new Breach of Earth-8, a Ronnie Raymond/Nathaniel Adam fusion called "Quantum-Storm" from Earth-37, and another from Earth-38 who rules over his Atomic Knights. Additionally, issue #1 introduces a "Brigadier Atom" from Earth-13 married to Nightshade, and in "Countdown: Arena" #3, Breach gathers together a group