claim: The Vandals established kingdoms only in Portugal and Britain.
evidence: In theoretical physics , a Nielsen -- Olesen vortex is a point-like object localized in two spatial dimensions or , equivalently , a classical solution of field theory with the same property .. theoretical physics. theoretical physics. field theory. field theory ( physics ). This particular solution occurs if the configuration space of scalar fields contains non-contractible circles .. A circle surrounding the vortex at infinity may be `` wrapped '' once on the other circle in the configuration space .. A configuration with this non-trivial topological property is called the Nielsen -- Olesen vortex , after Holger Bech Nielsen and Poul Olesen -LRB- 1973 -RRB- .. Holger Bech Nielsen. Holger Bech Nielsen. Poul Olesen. Poul Olesen