In 2009, a passive cloaking device was designed to be an 'external invisibility device' that leaves the concealed object out in the open so that it can ‘see’ its surroundings. This is based on the premise that cloaking research has not adequately provided a solution to an inherent problem; because no electromagnetic radiation can enter or leave the cloaked space, this leaves the concealed object of the cloak without ability to detect visually, or otherwise, anything outside the cloaked space.