•1788 – Lagrange, viewed mechanics as a 4D system in Euclidean spacetime
•1823 – Mobius, showed that in 4D you could rotate a 3D object onto its mirror-image
•1840 – Grassmann, investigated n-dimensional geometries
•1843 – Hamilton, invented quaternions, a 4D operational space for rotations and othertransformations such as symmetry and scale
•1853 – Schlafli, developed many polytopes (higher-D polyhedrons) in higher dimensions
•1880 – Charles Hinton, first to treat the possibility of a 4D physical reality
•1884 – Edwin Abbott Abbott, Flatland: A Romance in Many Dimensions
•1905 – Rudolf Steiner, Berlin lecture on the Fourth Dimension
•1908 – Hermann Minkowski, invented non-Euclidean 4D spacetime; this was applied byEinstein
•1979 – Salvador Dali, Painting: Search for the Fourth Dimension
•2009 – Mike Ambinder, “Human four-dimensional spatial intuition in virtual reality”