Four years ago John Pendry of Imperial College, London, described how a composite copper structure could be used to create a material with negative electric permittivity, and more recently he proposed how the magnetic permeability could be made negative as well. Since the permittivity and permeability describe how the material responds to applied electric and magnetic fields, together they determine how the material will respond to an electromagnetic field. The UCSD team has now made a copper structure that exhibits this left-handed behaviour at microwave frequencies.