  Superconductors have often been described as `giant atoms'. The simplest
description of atoms that heralded their quantum understanding was proposed by
Bohr in 1913. The Bohr atom starts from some simple assumptions and deduces
that the angular momentum of the electron in Bohr orbits is quantized in
integer units of $\hbar$. This remarkable result, which does not appear to be
implicit in the assumptions of the model, can be interpreted as a `theoretical
proof' of the model's validity to describe physical reality at some level.
Similarly we point out here that from some simple assumptions it can be deduced
that electrons in superconductors reside in mesoscopic orbits with orbital
angular momentum $\hbar/2$. This implies that both in superconductors and in
ferromagnets the long-range order results from elementary units of identical
angular momentum. Similarly to the case of the Bohr atom we propose that this
remarkable result is compelling evidence that this physics, which is not part
of conventional BCS theory, describes physical reality at some level and
heralds a qualitatively new understanding of superconductors.
