This is the number of possible arrangements of a pair of identical bosons in a two-level system. A DC circuit that exhibits damped harmonic oscillation must contain at least this many passive elements. This is the smallest nonexistent multipole moment. Any gravitating system with at least this many bodies is not analytically integrable. The electron's charge is this number times the down quark charge. The thermodynamic law of this number isn't really a law, and describes the entropy of ideal crystals in a certain limit. There are this many generations of quarks. For 10 points, give this number that is also the number of observable spatial dim
This is the number of possible arrangements of a pair of identical bosons in a two-level system. A DC circuit that exhibits damped harmonic oscillation must contain at least this many passive elements. This is the smallest nonexistent multipole moment. Any gravitating system with at least this many bodies is not analytically integrable. The electron's charge is this number times the down quark charge. The thermodynamic law of this number isn't really a law, and describes the entropy of ideal crystals in a certain limit. There are this many generations of quarks. For 10 points, give this number that is also the number of observable spatial dimensions in the universe.
This is the number of possible arrangements of a pair of identical bosons in a two-level system.