The concept of higher spatial dimension extends our familiar three-dimensional space—length, width, and height—by introducing additional directions which are perpendicular to all three.

Armed with his new understanding, the square conceives the possibility of a fourth dimension. He even goes so far as to suggest that there may be no limit to the number of spatial dimensions.

Spatial genetic multiplicity means an echo and ... a nod to the classic 1975 story Genesis of The Daleks, in which the Fourth Doctor and Sarah Jane travelled to Skaro in order to stop the Daleks ...